Ambient air quality report

              2008 Ambient Air Quality Report
STATE OF NORTH CAROLINA
Beverly Eaves Perdue, Governor
DEPARTMENT OF
ENVIRONMENT
AND
NATURAL RESOURCES
Dee Freeman, Secretary
DIVISION OF AIR QUALITY
Sheila C. Holman, Director
AMBIENT MONITORING SECTION
Donald D. Redmond, Jr., Chief
PUBLISHED
November 2011
ii
2008 Ambient Air Quality Report
Ambient Monitoring Section Report # 2011.02
Acknowledgements:
Primary Author: Wayne Cornelius
Additional Assistance: Lucyna Kozek
Vitaly Karpusenko
John Holland
Public Sources of Data:
North Carolina Division of Air Quality
http://daq.state.nc.us/
Forsyth County Environmental Affairs Department
http://www.co.forsyth.nc.us/EnvAffairs/weathereport.htm
EPA/AQS Air Quality Subsystem
http://www.epa.gov/airsweb
National Atmospheric Deposition Program
http://nadp.sws.uiuc.edu
Published: November 2011
Not copyrighted.
iii
Preface
This report is issued by the Division of Air Quality of the Department of Environment and Natural Resources to inform the public about air pollution levels throughout the state of North Carolina. It describes the sources and effects of the following pollutants for which the U.S. Environmental Protection Agency and the State of North Carolina have established ambient air quality standards:
Particulate Matter
Sulfur Dioxide
Ozone
Carbon Monoxide
Nitrogen Dioxide
Lead
The report begins with a brief discussion of the ambient air monitoring program, including a description of the monitoring network. It presents detailed results of monitoring that was conducted in 2008 to measure the outdoor concentrations. The data are presented graphically and as statistical summaries, including comparisons to the ambient air quality standards. The report discusses the recorded data, and the seasonal variability of some pollutants. Data and areas exceeding the ambient air quality standards are identified. Factors that have contributed to those exceedances are also described.
Acid rain data summaries from the National Atmospheric Deposition Program/National Trends Network for North Carolina also are included for 2008.
Current air pollution information is available to the public 24 hours a day on the Division of Air Quality‟s website http://www.ncair.org/monitor/aqi/.
In 2002, the air monitoring program deployed a network of fine particle speciation monitors. This report provides data summaries from these monitors for 2008.
Also in 2002, the Division of Air Quality established a small network of Urban Air Toxics monitors. It supplements a new national toxics database, and some key toxics pollutants are summarized for 2008 in this report.
The report also contains graphical summaries of long-term annual trends for the criteria pollutants and acid rain data, highlighting successful efforts at pollution control and suggesting where future priorities should be placed.
Additional copies of this report and previous annual reports are available on the Division of Air Quality‟s website http://www.ncair.org/monitor/reports/ or by writing to:
iv
Division of Air Quality
1641 Mail Service Center
Raleigh, North Carolina 27699-1641
Comments regarding this report or suggestions for improving future reports are welcomed. Comments may be sent to Dr. Wayne L. Cornelius, at the above address.
Sheila C. Holman, Director
Division of Air Quality
v
Executive Summary
In 2008, the North Carolina Division of Air Quality (DAQ), the three local program agencies and one tribal agency (listed in Appendix A) collected 313,811ambient air quality samples. These samples included measurements of the U.S. Environmental Protection Agency‟s (EPA) criteria air pollutants: particulate matter, carbon monoxide, ozone, sulfur dioxide, nitrogen dioxide and lead. This report discusses each pollutant and presents summary tables, maps, charts and explanations of the data.
The report also includes data from weekly acid rain samples collected by the National Atmospheric Deposition Program (NADP) at seven North Carolina sites and one Tennessee site very close to the North Carolina border. It discusses acid rain and presents summary tables, maps, charts and explanations of the data.
This report provides data summaries from a network of fine particle speciation monitors for 2008. The DAQ and two federal agencies deployed these monitors in 2002 to characterize more fully fine particulate matter by composition. This report presents a map and summary tables of the major speciation categories for 2008.
Also in 2002, the Division of Air Quality established a small network of Urban Air Toxics monitors. It supplements a new national toxics database, and some key toxics pollutants are summarized for 2008 in this report. This report presents a map and summary tables of formaldehyde and five important volatile organic compounds for 2008.
The report also contains graphical summaries of long-term annual trends for the criteria pollutants and acid rain data, highlighting successful efforts at pollution control and suggesting where future priorities should be placed.
Three different types of particulate matter are routinely sampled in North Carolina. Total Suspended Particulate (TSP), or particles having an aerodynamic diameter of 100 micrometers or less, is regulated by North Carolina standards. Particulate matter (PM10), with a mean aerodynamic diameter less than or equal to a nominal 10 micrometers (0.00004 inches), is regulated by both EPA and N.C. standards. Fine particulate matter (PM2.5), with a mean aerodynamic diameter less than or equal to a nominal 2.5 micrometers (0.00001 inches), has been regulated by EPA and NC since 1999.
No TSP sampling occurred in 2008. In 2006, TSP was sampled at seven sites, yielding 361 daily samples. There were no exceedances of the state TSP ambient air quality standard for 24-hour samples (150 g/m3) observed in 2006.
vi
PM10 was sampled at 13 sites, yielding 1,344 daily samples. There were no exceedances of the National Ambient Air Quality Standards for PM10 (150 g/m3 for 24-hour samples and 50 g/m3 for the annual arithmetic mean).
PM2.5 was sampled at 33 sites yielding 3,893 daily samples. There were 10 exceedances of the ambient air quality standards for PM2.5 (35 g/m3 for 24-hour samples). Nine of the exceedances were officially attributed to wildfires and are therefore omitted from calculations of the PM2.5 “daily” design value based on the 98th percentile statistic. None of the 35 sites exceeded the annual arithmetic mean standard of 15 g/m3.
Carbon monoxide (CO), largely results from fuel combustion. The most likely areas to have excessive CO concentrations are larger cities where there are more cars and congested streets.
CO was sampled at seven sites, yielding 41,655 valid hourly averages. The National Ambient Air Quality Standards for CO are 35 ppm for the maximum one-hour average and 9 ppm for the maximum eight-hour average. There were no exceedances of the standards. The highest one-hour concentration of 4.0 ppm was observed at 3801 Spring Forest Rd. in Raleigh. The highest eight-hour concentration of 2.4 ppm was observed at 3801 Spring Forest Rd. The mean one-hour average has been decreasing by about 15 percent per year and the mean eight-hour average has been decreasing by about 38 percent per year. The combined effects of newer cars in the vehicle fleet, traffic control strategies, and the Inspection and Maintenance program in 48 Counties has helped reduce the number and intensity of CO exceedances from previous years.
Ozone (O3) forms in the lower atmosphere when hydrocarbons (or volatile organic compounds) and nitrogen oxides chemically react in the presence of sunlight and high temperatures. The main emphasis in control of ozone has been to limit hydrocarbon and nitrogen oxide emissions.
O3 was sampled at 40 sites, yielding 199,944 valid hourly averages. The National Ambient Air Quality Standard for O3 in 2008 was 0.075 ppm for the maximum eight-hour average and 0.12 ppm for the maximum one-hour average.
In 2008, there were no exceedances of the one-hour standard.
In 2008, the 8-hour standard was exceeded 197 times, on 36 different days, with one county having fifteen exceedances at individual sites. The site at 29N@ Mecklenburg Cab Co, Charlotte in Mecklenburg County had the highest number, 15.
Sulfur dioxide (SO2) is mainly produced by combustion of fossil fuels containing sulfur compounds and the manufacture of sulfuric acid.
SO2 was sampled at seven sites, yielding 50,013 valid hourly averages. There were no exceedances of the National Ambient Air Quality Standards (365 g/m3 or 0.14 ppm for a 24-hour average, 1300 g/m3 or 0.50 ppm for a three-hour average, 80 g/m3 or 0.03 ppm for the annual arithmetic mean) at network monitoring sites.
vii
Nitrogen oxides (NOx) are produced primarily from the burning of fossil fuels such as coal, oil and gasoline, due to the oxidation of atmospheric nitrogen and nitrogen compounds in the fuel. The primary combustion product is NO, which reacts with hydrocarbons, ozone and other atmospheric compounds to form NO2. NOx compounds play an important role in the formation of ozone. Reactive nitrogen species (NOy) were monitored in Charlotte and Winston-Salem to gather data for the development of control strategies for ozone non-attainment areas.
The criteria pollutant NO2 was sampled at two sites, yielding 16,962 valid hourly averages. There were no exceedances of the National Ambient Air Quality Standard (0.053 ppm for the annual arithmetic mean). The mean one-hour average concentration has been increasing by about 2 percent per year.
Lead (Pb) emissions result from coal combustion and the sandblasting of highway bridges, overpasses, and water tanks. In the past, the combustion of gasoline containing tetraethyl lead as an additive was a major source.
Lead was not sampled in 2008 using a Federal Reference Method. There have been no recent exceedances of the ambient air quality standard for lead (1.5 g/m3 for a quarterly arithmetic mean). From 1979 through 1999, mean lead concentrations have decreased by 92 percent. The steady decline in the use of leaded gasoline is primarily responsible for this trend.
Acid Rain is produced when nitrate and sulfate ions from motor vehicles, combustion and industrial sources reach the upper atmosphere, react with moisture in the air, and are deposited as acid precipitation.
The annual mean pH in 2008 ranged from 4.74 (Rowan County) to 5.07 (Sampson County). The annual total deposition of mercury in precipitation ranged from 7.5 ng/m2 (Columbus County) to 8.3 ng/m2 (Washington County).
Atmospheric mercury is a by-product of combustion processes and mining and is also outgassed naturally by volcanoes and geothermal vents. Monitoring of pH and other ion concentrations in precipitation will help to identify trends and demonstrate the results of efforts to reduce emissions from mobile and industrial sources.
Speciated particulate samples were collected at eight sites by the DAQ, two sites by the National Park Service and one site by the U.S. Forest Service. Categorizing these as nitrates, sulfates, ammonium, organic carbon, elemental carbon, crustal material, and “other” constitutents (liquid water, trace elements, etc.), there were 3,666 quantifiable concentrations in 2008.
By category, the highest concentrations of speciated particulate samples in 2008 were: sulfate 17.20 μg/m3; organic carbon 15.00 μg/m3; nitrate 5.32 μg/m3; crustal component 4.24 μg/m3 ; ammonium 3.73 μg/m3 and elemental carbon 2.67 μg/m3 .
viii
Although there was no sampling for lead using a criteria pollutant method, the speciated particulate monitoring network provided 869 samples of PM2.5 lead in 2008; 864 of these sample concentrations (99 percent) were less than 0.01 μg/m3. Five samples exceeded 0.014 μg/m3.
Urban Air Toxics sampling in 2008 occurred at seven sites, six urban and one rural. This effort contributes to the U.S. EPA‟s Air Toxics Monitoring Strategy by providing data to help assess health risks.
The median concentrations of formaldehyde were 1.36 to 3.76 ppb at the urban sites and 1.29 ppb at the rural site. Median benzene concentrations were 0.15 to 0.42 ppb at the urban sites and 0.11 ppb at the rural site. Median toluene concentrations were 0.18 to 0.46 ppb at the urban sites and 0.10 ppb at the rural site. Median ethylbenzene concentrations were 0.05 to 0.10 ppb at the urban sites and 0.05 ppb at the rural site. Median m/p-xylene concentrations were 0.05 to 0.11 ppb at the urban sites and 0.05 ppb at the rural site. Median o-xylene concentrations were 0.05 to 0.09 ppb at the urban sites and 0.05 at the rural site. Median 1, 3-butadiene concentrations were 0.05 ppb at the urban sites and at the rural site. Ambient monitoring data for hazardous and/or toxic air pollutants are available in the Annual Air Toxics Report.
Ambient Trends: Annual average statewide concentrations of PM10 decreased by 39 percent from 1989 to 2008. Annual average statewide concentrations of CO (as 8-hour averages) have decreased by 62 percent from 1997 to 2008. Annual average highest 8-hour ozone concentrations decreased by 11 percent from 1990 to 2008. Annual average highest 3-hour sulfur dioxide concentrations decreased by 66 percent from 1989 to 2008, and annual average of annual means decreased by 59 percent in the same time period. Annual average nitrogen dioxide concentrations remained constant from 1989 to 2008 in Forsyth County and Mecklenburg County, the only locations where this pollutant is monitored at present.
Acid Rain Trends: Annual average pH in rain increased about 7 percent from 1991 to 2008. Annual average ammonium concentrations increased about 28 percent from 1991 to 2008, but this was dominated by very significant increases in Sampson County associated with concentrated livestock animal production. Annual average nitrate concentrations in rain decreased about 28 percent from 1991 to 2008. Annual average sulfate concentrations in rain decreased about 34 percent from 1991 to 2008.
ix
CONTENTS
1. Introduction ............................................................................................................................... 1
2 Descriptions of Criteria Pollutants ............................................................................................. 2
2.1 Particulate Matter ..................................................................................................................... 2
2.1.1 Sources ................................................................................................................................ 2
2.1.2 Effects ................................................................................................................................ 2
2.2 Carbon Monoxide .................................................................................................................... 3
2.2.1 Sources ............................................................................................................................... 3
2.2.2 Effects ................................................................................................................................ 3
2.3 Ozone ...................................................................................................................................... 3
2.3.1 Sources ............................................................................................................................... 4
2.3.2 Effects ................................................................................................................................ 4
2.4 Sulfur Dioxide ......................................................................................................................... 4
2.4.1 Sources................................................................................................................................ 4
2.4.2 Effects ................................................................................................................................. 4
2.5 Nitrogen Oxides ...................................................................................................................... 5
2.5.1 Sources................................................................................................................................ 5
2.5.2 Effects ................................................................................................................................. 5
2.6 Lead ........................................................................................................................................ 5
2.6.1 Sources................................................................................................................................ 5
2.6.2 Effects ................................................................................................................................. 6
3 Standards .................................................................................................................................. 7
4 Ambient Air Quality Monitoring Program ............................................................................... 9
5 Pollutant Monitoring Results .................................................................................................. 16
5.1 Total Suspended Particulates ................................................................................................. 16
5.2 PM10 ...................................................................................................................................... 18
5.3 Fine Particulate Matter, (PM2.5) ............................................................................................ 21
5.4 Carbon Monoxide ................................................................................................................. 28
5.5 Ozone ................................................................................................................................... 31
5.6 Sulfur Dioxide ....................................................................................................................... 39
5.7 Nitrogen Dioxide .................................................................................................................. 43
5.8 Lead ..................................................................................................................................... 44
5.8.1 Special Studies .................................................................................................................... 44
6 Air Quality Index ..................................................................................................................... 45
7 Acid Rain ................................................................................................................................ 54
7.1 Sources ................................................................................................................................. 54
7.2 Effects .................................................................................................................................. 54
7.3 Monitoring ............................................................................................................................ 54
8. Fine Particle Speciation ............................................................................................................ 59
8.1 Description of pollutants ......................................................................................................... 59
8.1.1 Nitrate ................................................................................................................................. 59
8.1.2 Sulfate ................................................................................................................................. 59 x
8.1.3 Ammonium .......................................................................................................................... 59
8.1.4 Organic Carbon .................................................................................................................... 59
8.1.5 Elemental Carbon................................................................................................................. 59
8.1.6 Crustal Component (Fine Dust) ........................................................................................... 60
8.1.7 “Other” Speciated components. ........................................................................................... 60
8.2 Sources ................................................................................................................................... 60
8.3 Effects .................................................................................................................................... 61
8.4 Monitoring .............................................................................................................................. 61
9. Urban Air Toxics ...................................................................................................................... 73
9.1 Sources .................................................................................................................................. 73
9.2 Effects ................................................................................................................................... 73
9.3 Formaldehyde ....................................................................................................................... 74
9.3.1 Sources .............................................................................................................................. 74
9.3.2 Effects ............................................................................................................................... 74
9.4 Benzene ............................................................................................................................. 74
9.4.1 Sources .............................................................................................................................. 74
9.4.2 Effects ............................................................................................................................... 75
9.5 Toluene ................................................................................................................................ 75
9.5.1 Sources ............................................................................................................................. 75
9.5.2 Effects .............................................................................................................................. 75
9.6 Ethylbenzene .......................................................................................................................... 75
9.6.1 Sources ............................................................................................................................. 75
9.6.2 Effects............................................................................................................................. 76
9.7 Xylene ................................................................................................................................... 76
9.7.1 Sources ............................................................................................................................. 76
9.7.2 Effects .............................................................................................................................. 76
9.8 1,3-Butadiene ........................................................................................................................ 76
9.8.1 Sources ............................................................................................................................. 76
9.8.2 Effects .............................................................................................................................. 77
9.9 Monitoring 2008 ................................................................................................................... 77
10 Statewide Trends ..................................................................................................................... 85
10.1 Particulate Matter ................................................................................................................ 85
10.2 Carbon Monoxide ............................................................................................................... 85
10.3 Ozone ................................................................................................................................. 85
10.4 Sulfur Dioxide ..................................................................................................................... 85
10.5 Nitrogen Dioxide ................................................................................................................ 85
10.6 pH ....................................................................................................................................... 86
10.7 Ammonium Ion ................................................................................................................... 86
10.8 Nitrate Ion ........................................................................................................................... 86
10.9 Sulfate Ion ........................................................................................................................... 86
Appendix A. Air Pollution Monitoring Agencies ......................................................................... 94
Appendix B. Exceptional Events .................................................................................................. 97
Appendix C. Box-And-Whisker Plots .......................................................................................... 98
Appendix D. Nonattainment and North Carolina ......................................................................... 99
xi
List of Tables
Table 3.1 National and North Carolina Ambient Air Quality Standards ........................................ 8
Table 4.1 Ambient Air Monitoring Sites Operated in North Carolina, 2008 ............................... 11
Table 5.1 Total Suspended Particulates in Micrograms Per Cubic Meter for 2008 ..................... 17
Table 5.2 PM10 in Micrograms Per Cubic Meter for 2008 ........................................................... 19
Table 5.3 PM2.5 in Micrograms Per Cubic Meter for 2008........................................................... 22
Table 5.4 Exceedances of the PM2.5 Standard in 2008 ................................................................ 25
Table 5.5 Carbon Monoxide in Parts Per Million for 2008 .......................................................... 29
Table 5.6 One-Hour Ozone in Parts Per Million for 2008 ........................................................... 32
Table 5.7 Eight-Hour Ozone in Parts Per Million for 2008 .......................................................... 36
Table 5.8 Sulfur Dioxide in Parts Per Million from All Sites for 2005-2008 .............................. 40
Table 5.9 Nitrogen Dioxide in Parts Per Million for 2008 ........................................................... 43
Table 6.1 Air Quality Index Category Days in the Major Metropolitan Statistical Areas, 2008 . 47
Table 7.1 pH, Conductivity in Microsiemans per Centimeter and Precipitation in Inches from the National Atmospheric Deposition Program for 2008 ........................................................... 56
Table 7.2 Ion Concentrations in Milligrams per Liter (Precipitation-weighted Annual Means) from the National Atmospheric Deposition Program Data for 2008 .................................... 57
Table 7.3 Precipitation-weighted mercury deposition totals for 2006-2008 ................................ 58
Table 8.1 Fine Particles Speciation Sites Operated in North Carolina in 2008 ............................ 63
Table 8.2 Mean and Maximum Nitrate PM2.5 Concentration for 2008 ........................................ 63
Table 8.3 Nitrate PM2.5- Micrograms/Cubic Meter (LC) for 2008 ............................................... 64
Table 8.4 Mean and Maximum Sulfate PM2.5 Concentration for 2008 ........................................ 65
Table 8.5 Sulfate PM2.5- Micrograms/Cubic Meter (LC) for 2008 .............................................. 65
Table 8.6 Mean and Maximum Ammonium PM2.5 Concentration for 2008 ................................ 66
Table 8.7 Ammonium Ion PM2.5- Micrograms/Cubic Meter (LC) for 2008 ................................ 67
Table 8.8 Mean and Maximum Organic Carbon PM2.5 Concentration for 2008 .......................... 67
Table 8.9 Organic Carbon CSN PM2.5- Micrograms/Cubic Meter (LC) for 2008 ....................... 68
Table 8.10 Mean and Maximum Elemental Carbon PM2.5 Concentration for 2008 .................... 69
Table 8.11 Elemental Carbon CSN PM2.5- Micrograms/Cubic Meter (LC) for 2008 .................. 69
Table 8.12 Mean and Maximum Crustal Component PM2.5 Concentration for 2008 .................. 70
Table 8.13 Crustal Component PM2.5- Micrograms/Cubic Meter (LC) for 2008 ......................... 71
Table 8.14 Mean and Maximum Lead PM2.5 Concentration for 2008 .......................................... 71
Table 8.15 Lead PM2.5- Micrograms/Cubic Meter (LC) for 2008 ................................................ 72
Table 9.1 Formaldehyde - Parts per billion for 2008 .................................................................... 79
Table 9.2 Benzene - Parts per billion for 2008 ............................................................................. 80
Table 9.3 Toluene - Parts per billion for 2008 .............................................................................. 81
Table 9.4 Ethylbenzene - Parts per billion for 2008 ..................................................................... 81
Table 9.5 m/p-Xylene - Parts per billion for 2008 ........................................................................ 82
Table 9.6 o-Xylene -Parts per billion for 2008 ............................................................................. 83
Table 9.7 1,3-Butadiene ................................................................................................................ 83 xii
List of Figures
Figure 4.1 Monitoring Sites Active in 2008 ................................................................................. 10
Figure 5.1 Location of PM10 Monitoring Sites ............................................................................. 18
Figure 5.2 PM10: Second Highest 24-Hour Averages, 2008 ........................................................ 20
Figure 5.3 PM10: Maximum Annual Arithmetic Means, 2008 .................................................... 20
Figure 5.4 Location of PM2.5 Monitoring Sites ............................................................................ 22
Figure 5.5 PM2.5: 98th percentile, 2008 ........................................................................................ 26
Figure 5.6 PM2.5: Annual Arithmetic Means, 2008 ..................................................................... 26
Figure 5.7 PM2.5: Design Values by County, 2005-2008 ............................................................ 27
Figure 5.8 Location of Carbon Monoxide Monitoring Sites ........................................................ 29
Figure 5.9 Carbon Monoxide: Second Highest 1-Hour Concentration, 2008 .............................. 30
Figure 5.10 Carbon Monoxide: Second Highest Non-overlapping 8-Hour Concentration, 2008 30
Figure 5.11 Location of Ozone Monitoring Sites ......................................................................... 32
Figure 5.12 Ozone: Second Highest Annual 1-Hour Average, 2008 ........................................... 38
Figure 5.13 Ozone: Mean Annual Fourth Highest 8-Hour Average, 2005-2008 ........................ 38
Figure 5.14 Locations of Sulfur Dioxide Monitoring Sites in 2005, 2006 and 2008 ................... 40
Figure 5.15 Sulfur Dioxide: Second Highest 3-Hour Averages in the Most recent Year of Data
from 2005, 2006 and 2008 .................................................................................................... 42
Figure 5.16 Sulfur Dioxide: Second Highest 24-Hour Averages in the Most Recent Year of Data from 2005, 2006 or 2008 ...................................................................................................... 42
Figure 5.17 Location of Nitrogen Dioxide Monitoring Sites ...................................................... 43
Figure 6.1 Daily Air Quality Index Values for Asheville ............................................................ 48
Figure 6.2 Daily Air Quality Index Summary for Asheville ........................................................ 48
Figure 6.3 Daily Air Quality Index Values for Charlotte-Gastonia .............................................. 49
Figure 6.4 Daily Air Quality Index Summary for Charlotte-Gastonia ......................................... 49
Figure 6.5 Daily Air Quality Index Values for Fayetteville ......................................................... 50
Figure 6.6 Daily Air Quality Index Summary for Fayetteville ..................................................... 50
Figure 6.7 Daily Air Quality Index Values Greensboro-Winston-Salem-High Point .................. 51
Figure 6.8 Daily Air Quality Index Summary Greensboro-Winston-Salem-High Point .............. 51
Figure 6.9 Daily Air Quality Index Values for Raleigh-Durham- Chapel Hill ............................ 52
Figure 6.10 Daily Air Quality Index Summary for Raleigh-Durham-Chapel Hill ....................... 52
Figure 6.11 Daily Air Quality Index Values for Wilmington ....................................................... 53
Figure 6.12 Daily Air Quality Index Summary for Wilmington .................................................. 53
Figure 7.1 Annual Mean pH Values at North Carolina NADP Sites, 2008.................................. 55
Figure 7.2 Location of Mercury Monitoring Sites ........................................................................ 58
Figure 8.1 Location of Nitrate, Sulfate, Ammonium, Organic Carbon, Elemental Carbon, Crustal
component, "Other" component, Monitoring Sites 2008 ...................................................... 62
Figure 9.1 Location Urban Air Toxics Monitoring Sites 2008 ..................................................... 79 xiii
Figure 10.1 Distribution of Statewide Second-Maximum 24-Hour PM10 Concentrations, 1989-
2008, and Smoothed Regression Trend Line ....................................................................... 87
Figure 10.2 Distribution of Statewide Second-Maximum 8-Hour Carbon Monoxide
Concentrations, 1996-2008, and Smoothed Regression Trend Line ................................... 86
Figure 10.3 Distribution of Statewide Fourth-Maximum 8-Hour Ozone Concentrations, 1990-
2008, and Smoothed Regression Trend Line ....................................................................... 88
Figure 10.4 Number of Days with Exceedances of 8-Hour Ozone Averages of 0.085 ppm or
Greater, 1990-2008 ............................................................................................................ 88
Figure 10.5 Distribution of Statewide Second-Maximum 3-Hour Sulfur Dioxide Concentrations,
1989- 2008, and Smoothed Regression Trend Line ............................................................ 89
Figure 10.6 Distribution of Statewide Second- Maximum 24-Hour Sulfur Dioxide
Concentrations, 1989- 2008, and Smoothed Regression Trend Line ................................. 89
Figure 10.7 Distributions of Forsyth and Mecklenburg County Annual Mean Nitrogen Dioxide
Concentrations, 1989- 2008, and Smoothed Regression Trend Line .................................. 90
Figure 10.8 Distribution of Statewide Annual Mean pH, 1991- 2008.......................................... 90
Figure 10.9 Distribution of Statewide Annual Mean Ammonium Ion Concentrations,
1991- 2008 .......................................................................................................................... 91
Figure 10.10 Distribution of Statewide Annual Mean Nitrate Ion Concentrations, 1991- 2008,
and Smoothed Regression Trend Line ................................................................................. 91
Figure 10.11 Distribution of Statewide Annual Mean Sulfate Ion Concentrations, 1991- 2008,
and Smoothed Regression Trend Line .................................................................................. 92
xiv
1
1. Introduction
This annual report summarizes the ambient air monitoring performed in calendar year 2008 by the North Carolina Division of Air Quality (DAQ), three local air pollution agencies and one tribal agency, which are more fully described in Appendix A.
These agencies collected 314,515 air quality samples of the U.S. Environmental Protection Agency‟s (EPA) criteria pollutants (particulate matter, carbon monoxide, ozone, sulfur dioxide, nitrogen dioxide and lead), which are discussed in this report.
Chapter 2 describes the criteria pollutants and discusses their sources and effects on human health, plants and animals.
Chapter 3 outlines the standards applied to criteria pollutant concentrations established by the EPA and the state of North Carolina to protect human health (primary standards) and plants, animals, and property (secondary
standards).
Chapter 4 describes the ambient monitoring program conducted by DAQ and three local program agencies.
Chapter 5 gives detailed monitoring results for each pollutant, with a map of the monitor sites, a table of the monitor summary statistics relevant to the standards, one or more maps summarizing the important statistics for each county with monitors, and
additional summaries as appropriate to each pollutant.
Chapter 6 describes the EPA Air Quality Index for the criteria pollutants and charts index measurements for five Metropolitan Statistical Areas of North Carolina.
Chapter 7 presents sources, effects and monitoring of acid rain data conducted in North Carolina by the National Atmospheric Deposition Program, National Trends Network and Mercury Deposition Network. It also includes a map of the calendar year mean pH level and site statistics for the calendar year in two tables.
Chapter 8 describes a small network of fine particulate speciation compounds. The chapter contains annual summaries of seven main components of fine particles. We also report summary of lead here (instead of chapter 5).
Chapter 9 describes the Urban Air Toxics monitoring program in North Carolina. The DAQ and local air pollution agencies sampled volatile organic compounds at seven sites. This chapter contains annual summaries for five important toxic pollutants.
Chapter 10 provides a statewide summary of trends for the criteria pollutants from 1989 and 1991 (1997 for CO and 1990 for O3) through 2008.
2
2 Descriptions of Criteria Pollutants
2.1 Particulate Matter
Atmospheric particulate matter is defined as any airborne material, except uncombined water (liquid, mist, steam, etc.), that exists in a finely divided form as a liquid or solid at standard temperature (25° C) and pressure (760 mm mercury) and has an aerodynamic diameter of less than 100 micrometers (m). In the period covered by this report, three sizes of particulate matter were monitored, total suspended particulate (TSP), PM10 and PM2.5. TSP is any particulate matter measured by the method described in EPA regulations 40 CFR 50 App. B (United States Environmental Protection Agency [US EPA] 1993, p. 715-728) and is generally considered to be particles having an aerodynamic diameter of 40 m or less (Watson and Chow 2001), although particles up to about 100 m are sometimes captured by samplers. (The probability of inhalation for 100 m particles is about 50 percent and increases with decreasing particle size [Maynard and Jensen 2001].) PM10 is particulate matter with an aerodynamic diameter less than or equal to 10 m as measured according to EPA regulations 40 CFR 50 App. J (US EPA 1993, p. 769-773). TSP measurements have been made in North Carolina since the early 1960s, and PM10 has been sampled locally in Charlotte since 1985 and statewide since 1986 (North Carolina Department of Environment, Health, and Natural Resources 1991a). The PM2.5
standard was adopted by North Carolina on April 1, 1999 standard was adopted by North Carolina on April 1, 1999.
On May 14, 1999, the U.S. Court of Appeals
ruled the setting of the standard by EPA was
an unconstitutional use of authority and could be vacated. The Supreme Court later upheld the new standard. EPA continues to require monitoring for PM2.5.
2.1.1 Sources
Particulates are emitted by many human activities, such as fuel combustion, motor vehicle operation, industrial processes, grass mowing, agricultural tilling and open burning. Natural sources include windblown dust, forest fires, volcanic eruptions, and plant pollen.
Particles emitted directly from a source may be either fine (less than 2.5 m) or larger (2.5 - 60 m), but particles photo-chemically formed in the atmosphere will usually be fine. Generally, larger particles have very slow settling velocities and are characterized as suspended particulate matter. Typically, fine particles originate from condensation of materials produced during combustion or atmospheric reactions.
2.1.2 Effects
Particulate matter can cause health problems affecting the breathing system, including aggravation of existing lung and heart disease, limitation of lung clearance, changes in form and structure of organs, and development of cancer. Individuals most sensitive to the effects of particulate matter include those with chronic obstructive lung 3
or heart disease, those suffering from the flu, asthmatics, the elderly, children, and mouth breathers.
Health effects from inhaled particles are influenced by the depth of penetration of the particles into the respiratory system, the amount of particles deposited in the respiratory system, and by the biological reaction to the deposited particles. The risks of adverse health effects are greater when particles enter the tracheobronchial and alveolar portions of the respiratory system. Small particles can penetrate into these deeper regions of the respiratory system. Healthy respiratory systems can trap particles larger than 10 micrometers more efficiently before they move deeply into the system and can more effectively remove the particles that are not trapped before deep movement.
Particulate matter also can interfere with plant photosynthesis, by forming a film on leaves reducing exposure to sunlight. Particles also can cause soiling and degradation of property, which can be costly to clean and maintain.
Suspended particles can absorb and scatter light, causing reduction of visibility. This is a national concern, especially in areas such as national parks, historic sites and scenic attractions visited by sightseers.
2.2 Carbon Monoxide
Carbon monoxide (CO) is the most commonly occurring air pollutant. CO is a colorless and poisonous gas produced by incomplete burning of carbon-containing fuel.
2.2.1 Sources
Most atmospheric CO is produced by incomplete combustion of fuels used for vehicles, space heating, industrial processes and solid waste incineration. Transportation accounts for the majority of CO emissions. Boilers and other fuel burning heating systems are also significant sources.
2.2.2 Effects
Breathing carbon monoxide affects the oxygen-carrying capacity of the blood. Hemoglobin in the blood binds with CO more readily than with oxygen, starving the body of vital oxygen.
Individuals with anemia, lung and heart diseases are particularly sensitive to CO effects. Low concentrations affect mental function, vision and alertness. High concentrations can cause fatigue, reduced work capacity and may adversely affect fetal development. Chronic exposure to CO at concentrations as low as 70 ppm (80 mg/m3) can cause cardiac damage. Other health effects associated with exposure to CO include central nervous system effects and pulmonary function difficulties.
Ambient CO apparently does not adversely affect vegetation or materials.
2.3 Ozone
Ozone is a clear gas that forms in the troposphere (lower atmosphere) by chemical reactions involving hydrocarbons (or volatile organic compounds) and nitrogen oxides in the presence of sunlight and high temperatures. Even low concentrations of 4
tropospheric ozone are harmful to people, animals, vegetation and materials. Ozone is the most widespread and serious criteria air pollutant in North Carolina.
Ozone in the upper atmosphere (stratosphere) shields the earth from harmful effects of ultraviolet solar radiation. Stratospheric ozone can be damaged by the emission of chlorofluoro hydrocarbons (CFCs) such as Freon.
2.3.1 Sources
Ozone (O3) is the major component of a complex mixture of compounds known as photochemical oxidants. Ozone is not usually emitted directly into the atmosphere, but is formed by a series of complex reactions involving hydrocarbons, nitrogen oxides and sunlight. Ozone concentrations are higher during the daytime in late spring, summer and early autumn when the temperature is above 60º F and the sunlight is more intense.
Two natural sources of upper atmosphere ozone are solar radiation and lightning during thunderstorms. These are not significant sources of tropospheric (ground level) ozone.
2.3.2 Effects
Ozone is a pulmonary irritant, affecting the respiratory mucous membranes, as well as other lung tissues and respiratory functions. Ozone has been shown to impair normal function of the lung causing shallow, rapid breathing and a decrease in pulmonary function. Other symptoms of exposure include chest tightness, coughing and wheezing. People with asthma, bronchitis or emphysema probably will experience breathing difficulty when exposed to short-term concentrations between 0.15 and 0.25 ppm. Continued or repeated long-term exposure may result in permanent lung structure damage.
Ozone damages vegetation by injuring leaves. Ozone also accelerates material aging by cracking rubber, fading dyes and eroding paint.
2.4 Sulfur Dioxide
Sulfur dioxide (SO2) is a colorless, corrosive, harmful gas with a pungent odor. Smaller concentrations of sulfur trioxide and other sulfate compounds are also found in SO2 emissions. Sulfur oxides contribute to the formation of acid rain and the formation of particles that reduce visibility.
2.4.1 Sources
The main sources of SO2 are combustion of fossil fuels containing sulfur compounds and the manufacture of sulfuric acid. Other sources include refining of petroleum and smelting of ores that contain sulfur.
2.4.2 Effects
The most obvious health effect of sulfur dioxide is irritation and inflammation of body tissues brought in contact with the gas. Sulfur dioxide can increase the severity of existing respiratory diseases such as asthma, bronchitis, and emphysema. Sulfuric acid and fine particulate sulfates, which are formed from sulfur dioxide, also may cause 5
significant health problems. Sulfur dioxide causes injury to many plants. A bleached
appearance between the veins and margins on leaves indicates damage from SO2 exposure. Commercially important plants sensitive to SO2 include cotton, sweet potatoes, cucumber, alfalfa, tulips, apple trees, and several species of pine trees.
2.5 Nitrogen Oxides
Several gaseous oxides of nitrogen are normally found in the atmosphere, including nitrous oxide (N2O), nitric oxide (NO) and nitrogen dioxide (NO2). Nitrous oxide is a stable gas with anesthetic characteristics and typical ambient concentrations well below the threshold concentration for a biological effect. Nitric oxide is a colorless gas with ambient concentrations generally low enough to have no significant biological effect. Nitrogen dioxide is reddish-brown but is not usually visible at typical ambient concentrations.
2.5.1 Sources
The most significant nitrogen oxide emissions result from the burning of fossil fuels such as coal, oil and gasoline, due to the oxidation of atmospheric nitrogen and nitrogen compounds in the fuel. The primary combustion product is NO, which reacts to form NO2.
2.5.2 Effects
At typical concentrations, nitrogen dioxide has significant health effects as a pulmonary irritant, especially upon asthmatics and children. In North Carolina, a much greater health concern is the formation of ozone, which is promoted by the presence of NO2 and other nitrogen oxides.
Some types of vegetation are very sensitive to NO2, including oats, alfalfa, tobacco, peas and carrots. Chronic exposure causes chlorosis (yellowing) and acute exposure usually causes irregularly shaped lesions on the leaves.
Nitric oxide and nitrogen dioxide do not directly damage materials. However, NO2 can react with moisture in the air to produce nitric acid, which corrodes metal surfaces and contributes to acid rain.
High concentrations of NO2 may reduce visibility. Much of the brownish coloration sometimes observed in polluted air in winter months may be due to NO2.
2.6 Lead
Lead is a toxic heavy metal element occurring in the atmosphere as small particles.
2.6.1 Sources
The major source of atmospheric lead used to be the combustion of gasoline containing the additive tetraethyl lead as an anti-knock agent. However, the availability of leaded fuel has declined, and the concentration of lead in such fuel has decreased, minimizing
gasoline as a source. Significant remaining sources include coal combustion (lead exists
in very small quantities as an impurity in coal) and sandblasting of highway structures and water tanks. Lead also is used in some 6
batteries, paints, insecticides, newspaper inks and piston engine aircraft gasoline.
2.6.2 Effects
Lead (Pb) persists and accumulates in the environment and the human body. It may be inhaled, ingested, and eventually absorbed into the bloodstream and distributed to all body tissues. Exposure to low
concentrations interferes with blood production and specific enzyme systems. It is believed to cause kidney and nerve cell damage, and severe lead poisoning is known to cause brain damage in children.
7
3 Standards
Ambient air quality status is determined by measuring pollutant concentrations in outdoor air and comparing the measured concentrations to corresponding standards. The US EPA (Environmental Protection Agency) defines the ambient air as “that portion of the atmosphere, external to buildings, to which the general public has access.”
Ambient air quality standards are classified as primary and secondary. Primary standards are those established to protect public health. Secondary standards are those established to protect the public welfare from adverse pollution effects on soils, water, crops, vegetation, man-made materials, animals, wildlife, weather, visibility, climate, property, transportation, economy, and personal comfort and well-being. The scientific criteria upon which the standards are based are reviewed periodically by the EPA, which may reestablish or change the standards according to its findings.
A pollutant measurement that is greater than the ambient air quality standard for a specific averaging time is called an exceedance. The national primary, secondary and North Carolina ambient air quality standards that were in effect during 2008 are summarized in Table 3.1.
8
Table 3.1 National and North Carolina Ambient Air Quality Standards
For new or anticipated new standards, References in the Code of Federal Regulations are given. For standards expressed in parts per million, an equivalent mass per unit volume is also shown.
Pollutant/
Ambient Measurement/ (Reference)
Averaging Period
Type of Summary
Primary National (Health Related) Standard
Secondary National (Welfare Related) Standard
North Carolina Standard
TSP
24 hour average
1 year
geometric mean
(1)
(1)
75 μg/m3
1 day
2nd maximum
(1)
(1)
150 μg/m3
PM-2.5
24 hour average (40CFR50, App. N)
1 year
average2 arithmetic mean
15 μg/m3 (6)
15 μg/m3 (6)
15 μg/m3 (6)
1 day
average2 98th percentile
35 μg/m3 (8)
35 μg/m3
35 μg/m3 (6)
PM-10
24 hour average (40CFR50, App. N)
1 year
average2 arithmetic mean
50 μg/m3
50 μg/m3
50 μg/m3
1 day
average2 2nd maximum3
150 μg/m3
150 μg/m3
150 μg/m3
CO
1 hour average
8 hours
2nd maximum
9 ppm
(10 mg/m3)
9 ppm
(10 mg/m3)
1 hour
2nd maximum
35 ppm
(40 mg/m3)
35 ppm
(40 mg/m3)
O3
1 hour average (40CFR50, App. I)
1 hour
expected4 2nd maximum
0.12 ppm (235 μg/m3)
0.12 ppm (235 μg/m3)
0.12 ppm (235 μg/m3)
8 hours
average5 arithmetic mean 4th maximum
0.075 ppm (9) (157 μg/m3)
0.075 ppm (9) (157 μg/m3)
0.075 ppm (9) (157 μg/m3)
SO2
1 hour average
1 year
arithmetic mean
30 ppb (80 μg/m3)
0.03 ppm (80 μg/m3)
1 day
2nd maximum
14 ppb (365 μg/m3)
0.14 ppm (365 μg/m3)
3 hours (non-overlapping)
2nd maximum
50 ppb (1,300 μg/m3)
0.50 ppm (1,300 μg/m3)
NO2
1 hour average
1 year
arithmetic mean
0.053 ppm
(100 μg/m3)
0.053 ppm
(100 μg/m3)
0.053 ppm
(100 μg/m3)
Pb
24-hour average
3 months
arithmetic mean
0.15 μg/m3(10)
0.15 μg/m3(10)
0.15 μg/m3(10)
1. In 1987, National standards for PM-10 replaced those for TSP.
2. Arithmetic mean over the 3 most current years.
3. In July 1997, a percentile-based statistic replaced the 2nd maximum, but in May 1999 the 2nd maximum standard was reinstated.
4. Determined by adjusting for incomplete days and averaging over the most recent 3 consecutive, complete calendar years.
5. Arithmetic mean value over the most recent 3 consecutive, complete calendar years.
6. On April 1, 2000, North Carolina adopted the EPA PM2.5 and Ozone standards. On May 14, 2000, the US Court of Appeals ruled the new EPA PM2.5 standard vacated and the new 8-hour ozone standard as unenforceable. On appeal to the US Supreme Court the new standard was upheld.
7. To attain this standard, the 3-year average of the 98th percentile of 24-hour concentrations at each population-oriented monitor within an area must not exceed 35 μg/m3 (effective December 17, 2006).
8. On May 27, 2000, the one-hour ozone standard was rescinded by the Environmental Management Commission based on EPA uidance. The one-hour standard is being reinstated by EPA.
9. Effective May 27, 2008.
10. Effective October 15, 2008. 9
4 Ambient Air Quality Monitoring Program
The North Carolina Division of Air Quality, three local air pollution control programs, and one tribal program (Appendix A) performed ambient monitoring and analyses of samples in 2008. Ambient air monitoring data are used to determine whether air quality standards are being met; to assist in enforcement actions; to determine the improvement or decline of air quality; to determine the extent of allowable industrial expansion; and to provide air pollution information to the public. A list of all monitoring sites active in 2008 is presented in Table 4.1 and shown as a map in Figure 4.1. The locations of sites for individual pollutants are shown in Figures 5.1, 5.4, 5.8, 5.11, 5.14, and 5.17.
In general, ambient monitors are operated year-round, but in some cases seasonal variations in pollutant levels make it feasible to suspend sampling at certain times. Ambient carbon monoxide associated with transportation and heating tends to produce significant concentrations only in cold weather conditions, so (with the US EPA's permission) we generally operate these monitors only from October through March. Ozone concentrations, by contrast, are correlated positively with ambient temperature. US EPA regulations accordingly require monitoring in NC from April through October. Along with ozone at some locations, we also monitor ozone precursor pollutants. Indeed, one of the ozone precursors is carbon monoxide. See 5.4 for more information about seasonal carbon monoxide monitoring and 5.5 for more information about seasonal ozone monitoring.
Siting of monitors involves several considerations, including size of the area represented, distance from roadways and nearby sources, unrestricted air flow, safety, availability of electricity and security. Each site has a defined monitoring objective, and annual evaluations are conducted to ensure that the objectives are met. The four basic monitoring objectives are to determine:
 the highest concentration expected in an area;
 representative concentrations in areas of high population density;
 the impact of significant sources or source categories on ambient air quality;
 general background concentration levels.
All monitors have known precision, accuracy, interferences and operational parameters. The monitors as well as all measurement devices are carefully calibrated at predetermined frequencies, varying from daily to quarterly. Measurements are traceable to National Institute of Standards and Technology (NIST), when standards are available.
Monitoring and analyses are performed according to a set of standard operating procedures. Field personnel visit manual 10
sampling sites once every six days to replace sample media and check the operation and calibration of monitors. Personnel check continuous monitors at least twice monthly for correct instrument operation.
Monitoring agencies carry out quality assurance activities to determine the quality of the collected ambient data, improve the
quality of the data and evaluate how well the monitoring system operates. The goal of quality assurance activities is to produce high quality air pollution data with defined completeness, precision, accuracy, representativeness and comparability.
Microprocessors are used at most sites to collect the data. A computerized telemetry system aids in assembly of the data for submission to the US EPA. This enhances data validity, minimizes travel costs, and allows real-time data to be available by computer polling when needed. Numerous checks are performed to ensure that only valid data are reported.
Figure 4.1 Monitoring Sites Active in 200811
Table 4.1 Ambient Air Monitoring Sites Operated in North Carolina, 2008
SITE
ADDRESS
POLLUTANTS
COUNTY
37-001-0002
827 S GRAHAM & HOPEDALE RD
PM2.5
ALAMANCE
BURLINGTON
37-003-0004
106 WAGGIN TRAIL RD
O3
ALEXANDER
TAYLORSVILLE
37-011-0002
7510 BLUE RIDGE PARKWAY SPUR
O3
AVERY
LINVILLE
37-013-0006
NC 306 @ PCS ENTRANCE
SO2
BEAUFORT
AURORA
37-021-0030
ROUTE 191 SOUTH BREVARD RD
O3
BUNCOMBE
ASHEVILLE
37-021-0034
175 BINGHAM ROAD
PM2.5
BUNCOMBE
ASHEVILLE
37-027-0003
HWY 321 NORTH
O3
CALDWELL
LENOIR
37-033-0001
7074 CHERRY GROVE RD
O3
PM2.5
CO
CASWELL
REIDSVILLE
37-035-0004
1650 1ST STREET
PM10
PM2.5
CATAWBA
HICKORY
37-037-0004
325 RUSSETT RUN ROAD
O3
PM2.5
SO2
CHATHAM
PITTSBORO
37-051-0007
CUMBERLAND CO ABC BOARD, 1705 OWEN
CO
CUMBERLAND
DR
FAYETTEVILLE
37-051-0008
1/4 MILE SR1857/US301/1857
O3
CUMBERLAND
WADE
37-051-0009
4533 RAEFORD RD
PM10
PM2.5
CUMBERLAND
FAYETTEVILLE
37-051-1003
3625 GOLFVIEW RD
O3
CUMBERLAND
HOPE MILLS
12
SITE
ADDRESS
POLLUTANTS
COUNTY
37-057-0002
SOUTH SALISBURY STREET
PM2.5
DAVIDSON
LEXINGTON
37-059-0002
246 MAIN STREET
O3
DAVIE
COOLEEMEE
37-061-0002
HIGHWAY 50
PM2.5
DUPLIN
KENANSVILLE
37-063-0015
801 STADIUM DRIVE
CO
O3
PM2.5
DURHAM
DURHAM
37-065-0004
900 SPRINGFIELD RD
PM2.5
EDGECOME
ROCKY MOUNT
37-065-0099
7589 NC HIGHWAY 33 NW
O3
EDGECOME
TARBORO
37-067-0022
1300 BLK HATTIE AVENUE
PM10
O3
SO2
NO2
PM2.5
FORSYTH
WINSTON-SALEM
37-067-0023
1401 CORPORATION PARKWAY
CO
PM10
FORSYTH
WINSTON-SALEM
37-067-0028
6496 BAUX MOUNTAIN ROAD
O3
FORSYTH
WINSTON-SALEM
37-067-0030
FRATERNITY CHURCH
O3 PM2.5
FORSYTH
WINSTON-SALEM
37-067-1008
3656 PIEDMONT MEMORIAL DRIVE
O3
FORSYTH
WINSTON-SALEM
37-069-0001
431 S. HILLSBOROUGH STREET
O3
FRANKLIN
FRANKLINTON
37-071-0016
1622 EAST GARRISON BLVD
PM2.5
GASTON
GASTONIA
37-075-0001
FOREST ROAD 423 SPUR
O3
GRAHAM
KILMER
37-077-0001
WATER TREATMENT PLANT JOHN
O3
GRANVILLE
UMSTEAD HOSP
BUTNER
13
SITE
ADDRESS
POLLUTANTS
COUNTY
37-081-0013
205 WILOUGHBY BLVD
PM2.5
PM10
O3
GUILFORD
GREENSBORO
37-081-0014
2127 SANDY RIDGE ROAD
PM2.5
GUILFORD
37-081-1011
401 WEST WENDOVER
CO
GUILFORD
GREENSBORO
37-087-0004
2177 ASHEVILLE ROAD
O3
HAYWOOD
WAYNESVILLE
37-087-0012
550 VANCE STREET
PM2.5
HAYWOOD
WAYNESVILLE
37-087-0035
TOWER BLUE RIDGE PARKWAY
O3
HAYWOOD
MILE MARKER 410
37-087-0036
GREAT SMOKY MOUNTAINS
O3
HAYWOOD
NATIONAL PARK
37-089-1006
CORNER OF ALLEN & WASHINGTON ST'S
PM10
HENDERSON
HENDERSONVILLE
37-099-0006
US ROUTE 19 NORTH
PM2.5
JACKSON
CHEROKEE RESERVATION
37-101-0002
1338 JACK ROAD
O3
JOHNSTON
CLAYTON
37-107-0004
HIGHWAY 70 EAST AND HIGHWAY 58
O3
PM2.5
LENOIR
SOUTH
KINSTON
37-109-0004
1487 RIVERVIEW ROAD
O3
LINCOLN
LINCOLNTON
37-111-0004
BALWIN AVENUE (EAST MARION JR. HIGH
PM2.5
MC DOWELL
SCHOOL)
MARION
37-117-0001 1210 HAYES STREET O3 PM2.5
MARTIN JAMESVILLE
37-119-0003 FIRE STATION # 11, 620 WEST 28TH STR PM10
MECKLENBURG CHARLOTTE
14
SITE
ADDRESS
POLLUTANTS
COUNTY
37-119-0041
1130 EASTWAY DRIVE
CO
SO2
PM2.5
NO2
O3
MECKLENBURG
CHARLOTTE
37-119-0042
1935 EMERYWOOD DRIVE
PM2.5
MECKLENBURG
CHARLOTTE
37-119-043 513 RADIO ROAD PM2.5
MECKLENBURG CHARLOTTE
37-119-1001 FILTER PLANT PM10
MECKLENBURG DAVIDSON
37-119-1005
400 WESTINGHOUSE BLVD.
O3
PM10
MECKLENBURG
CHARLOTTE
37-119-1009
29 N @ MECKLENBURG CAB CO.
O3
MECKLENBURG
CHARLOTTE
37-121-0001
CITY HALL, SUMMIT STREET
PM2.5
MITCHELL
SPRUCE PINE
37-123-0001
112 PERRY DRIVE
PM2.5
MONTGOMERY
CANDOR
37-129-0002
6028 HOLLY SHELTER ROAD
O3
PM2.5
NEW HANOVER
CASTLE HAYNE
37-129-0006
HIGHWAY 421 NORTH
SO2
NEW HANOVER
WILMINGTON
37-135-0007
MASON FARM ROAD
PM2.5
ORANGE
CHAPEL HILL
37-145-0003
STATE HIGHWAY 49 SOUTH
O3
PERSON
ROXBORO
37-147-0005
851 HOWELL STREET
PM2.5
PITT
GREENVILLE
37-147-0006
403 GOVERNMENT CIRCLE
O3
PM2.5
PITT
GREENVILLE
37-155-0005
1170 LINKHAW ROAD
PM2.5
ROBESON
LUMBERTON
37-157-0099
6371 NC 65 @ BETHANY SCHOOL
O3
ROCKINGHAM
BETHANY
15
SITE
ADDRESS
POLLUTANTS
COUNTY
37-159-0021
301 WEST ST & GOLD HILL AVENUE
CO
O3
PM2.5
ROWAN
ROCKWELL
37-159-0022
925 NORTH ENOCHVILLE AVENUE
O3
ROWAN
CHINA GROVE
37-173-0002
CENTER ST/PARKS & RECREATION
O3
PM2.5
SWAIN
FACILITY
BRYSON CITY
37-179-0003
701 CHARLES STREET
O3
UNION
MONROE
37-183-0014
3801 SPRING FOREST ROAD
O3
PM2.5
PM10
SO2
CO
WAKE
RALEIGH
37-183-0016
201 NORTH BROAD STREET
O3
WAKE
FUQUAY-VARINA
37-183-0018
US HIGHWAY 70 WEST AND NC HIGHWAY
CO
WAKE
50 NORD
RALEIGH
37-183-0020
3720 LAKE WHEELER RD
PM2.5
WAKE
37-189-0003
361 JEFFERSON ROAD
PM2.5
WATAUGA
BOONE
37-191-0005
DILLARD MIDDLE SHOOL, DEVEREAU
PM2.5
WAYNE
STREET
GOLDSBORO
37-199-0004
STATE HIGHWAY 128
O3
YANCEY
BURNSVILLE
Sites operated in 2008
71
16
5 Pollutant Monitoring Results
Air quality in a given area is affected by many factors, including meteorological conditions, the location of pollutant sources, and the amount of pollutants emitted from them.
The speed and direction of air movement determine whether pollutant emissions cause exceedances of the ambient air quality standards and where those exceedances will occur. Atmospheric stability, precipitation, solar radiation and temperature also affect pollutant concentrations.
Geographic factors that affect concentrations include variables such as whether an area is urban or rural, and whether the area has mountains, valleys or plains.
Important economic factors affecting air quality include concentration of industries, conditions of the economy, and the day of the week.
Air quality also may be influenced by “exceptional events” in the short term. Exceptional events may be either natural (e.g., forest fire) or manmade (e.g., construction or demolition). Unusual data that can be attributed to an exceptional event are considered biased and may be omitted from data summaries when they are not representative of normal conditions. In the tabular listings in this report, data affected by exceptional events are
excluded, and are omitted from
summaries in charts. However they are addressed in the text of the report. A list
of typical exceptional events is given in Appendix B.
Data for the 2008 ambient air quality report were collected at 108 air pollutant monitors operated by state and local agencies in North Carolina (listed in Appendix A). To minimize operating expenses, some sulfur dioxide monitors are operated only every third year. Three of the 118 monitors used for this report operated most recently in 2007 or 2006.
5.1 Total Suspended Particulates
Total Suspended Particulate matter (TSP) is collected on filters using a “high volume” sampler (an EPA Reference Method). The sampler motor is set and calibrated to an air flow rate of 40±4 cubic feet per minute. Gravimetric analysis is performed by comparing the exposed filter weight to the unexposed filter weight. Weights are measured to the nearest 0.1 milligram. The difference between the exposed and unexposed weights is the amount of particulate collected from a known volume of air.
The state and local program agencies discontinued routine ambient TSP sampling at the end of 2000, but resumed a limited sampling program again in 2003. The agencies did not collect TSP samples in 2008, but in 2006 seven sites were used to monitor TSP and 361 samples were collected. A detailed summary of the data from each site is given in Table 5.1.
17
No sample exceeded the N.C. TSP ambient air quality standards in 2006. The highest 24-hour average was 69 g/m3 , which was 46 percent of the standard. This value occurred at the 6028 Holly Shelter Road site in Castle Hayne. Attainment status is based on the second highest 24-hour concentration and on the geometric mean of all the 24-hour concentrations at a given site.
The largest geometric mean TSP average was 29 g/m3, which is 39 percent of the level of the air quality standard. This value occurred at the 1650 1st Street site in Hickory and 205 Willoughby Boulevard site in Greensboro.
Table 5.1 Total Suspended Particulates in Micrograms Per Cubic Meter for 2006
SITE NUMBER
ADDRESS
NUM OBS
24-HOUR MAX
ARITH
MEAN
GEOM
MEAN
GEOM
SD
COUNTY
1st
2nd
3rd
4th
37-035-0004
1650 1st STREET
53
68
60
55
53
33
29
1.7
CATAWBA
HICKORY
37-081-0013
205 WILLOUGHBY BLVD
42
65
55
52
52
32
29
1.6
GUILFORD
GREENSBORO
37-087-0011
HAYWOOD
PROSPECT AND NORTHSIDE STR
58
62
50
50
49
29
26
1.7
CANTON
37-117-0001
1210 HAYES STREET
60
46
43
37
35
22
20
1.4
MARTIN
JAMESVILLE
37-129-0002
6028 HOLLY SHELTER RD
56
69
40
36
35
21
19
1.6
NEW HANOVER
CASTLE HAYNE
37-155-0005
1170 LINKHAW ROAD
56
57
49
48
43
28
25
1.7
ROBESON
LUMBERTON
37-183-0014
3801 SPRING FOREST RD
36
65
58
52
51
34
32
1.5
WAKE
RALEIGH
Total Samples
361
Total Sites Sampled
7
18
5.2 PM10
State and local program agencies in North Carolina use high volume samplers and size selective inlets to collect PM10 samples. A gravimetric analysis procedure (EPA Reference Method) is used to analyze the samples.
In 2008, 1,344 ordinary 24-hour samples of PM10 were collected from monitors located at 15 sites. A map of the PM10 sampling sites is shown in Figure 5.1, and a detailed summary of the data from each site is given in Table 5.2.
There were no exceedances of the PM10 ambient air quality standards in 2008. The highest 24-hour maximum concentration was 105 g/m3, or about 70 percent of the standard (150 g/m3). The highest annual arithmetic mean was 24.1 g/m3, which is about 48 percent of the standard (50 g/m3).
The second highest 24-hour concentrations are shown by county in Figure 5.2 and the annual arithmetic means are shown in Figure 5.3. (In counties with more than one PM10 monitoring site, the concentration reported in Figure 5.2 is the county-wide second maximum 24-hour concentration, and the mean reported in Figure 5.3 is the maximum arithmetic mean for the county.)
Figure 5.1 Location of PM10 Monitoring Sites
19
Table 5.2 PM10 in Micrograms Per Cubic Meter for 2008
SITE NUMBER
ADDRESS
NUM
OBS
24-HOUR MAXIMA
ARITH
MEAN
COUNTY
1st
2nd
3rd
4th
37-035-0004
1650 1ST. ST.
59
40
34
33
31
18.6
CATAWBA
HICKORY
37-051-0009
CUMBERLAND
4533 RAEFORD ROAD
FAYETTEVILLE
58
37
33
29
28
17.3
37-067-0022
1300 BLK. HATTIE AVE
364
73
36
36
36
16.2
FORSYTH
WINSTON-SALEM
37-067-0023
FORSYTH
1401 CORPORATION PARKWAY
365
83
44
42
39
18.9
WINSTON-SALEM
37-081-0013
205 WILOUGHBY BLVD
58
33
31
29
27
16.2
GUILFORD
GREENSBORO
37-089-1006
HENDERSON
CORNER OF ALLEN & WASHINGTON STS
53
37
31
27
26
17.0
HENDERSON-VILLE
37-119-0003
MECKLENBURG
FIRE STA #11 620 MORETZ STREET
52
46
45
40
38
23.6
CHARLOTTE
37-119-0041
1130 EASTWAY DRIVE
90
36
36
35
33
19.9
MECKLENBURG
CHARLOTTE
37-119-0042
1935 EMERYWOOD DRIVE
59
35
33
31
31
19.9
MECKLENBURG
CHARLOTTE
37-119-1001
FILTER PLANT
57
39
36
34
32
19.6
MECKLENBURG
DAVIDSON
37-119-1005
400 WESTINGHOUSE BLVD.
61
46
43
40
39
24.1
MECKLENBURG
CHARLOTTE
37-129-0002
6028 HOLLY SHELTER RD
8
21
20
16
16
14.8
NEW HANOVER
CASTLE HAYNE
37-183-0014
3801 SPRING FOREST RD.
60
105
43
40
37
16.9
WAKE
RALEIGH
Total Samples
1,344
Total Sites Sampled
13
20
Figure 5.2 PM10: Second Highest 24-Hour Averages, 2008
Figure 5.3 PM10: Maximum Annual Arithmetic Means, 2008
21
5.3 Fine Particulate Matter, (PM2.5)
In 2008, 33 sites were used to monitor PM2.5 and 3,893 samples were collected. A map of the PM2.5 sampling sites is shown in Figure 5.4 and a detailed summary of the data from each site is given in Table 5.3.
There were 10 exceedances of the PM2.5 24-hour ambient air quality standards in 2008. They are listed in Table 5.4. Nine of the exceedances occurred in early June and appeared to be caused by smoke from the Evans Road wildfire in the Pocosin Lake National Wildlife Refuge. The remaining exceedance in March at the New Hanover County monitoring station was associated with the Edna Buck Road wildfire in that county. Extensively detailed information about both of these fires is available online at http://www.ncair.org/monitor/projects/exceptional/exceptional_2008.shtml .
Because these fires were recognized as “exceptional events”, DAQ requested exclusion of nine of these exceedances from consideration as violations of the standard, and EPA concurred with the requests. Requesting exclusion of the tenth exceedance was in the purview of the Forsyth County air monitoring program, but this agency declined the opportunity to request it. Apart from the exceedances caused by the wildfires, the highest concentrations observed were a 32.2 at Rocky Mount on June 11 (influenced by the Evans Road fire but not so strongly as to exceed the standard) and 31.8 at US RT 19 North, Cherokee NC on Aug. 8, 2008.
The highest annual arithmetic mean was 14.29 g/m3, which is about 5 percent below the level of the standard
(15 g/m3), at Lexington in Davidson County. (See Table 5.3).
NAAQS attainment is based on both the level of the 98th percentile concentration of 24 hour averages and weighted annual means (Table 3.1). The 98th percentile concentrations are shown by county in Figure 5.5, and the annual arithmetic means are shown in Figure 5.6. (In counties with more than one monitoring site, the concentration reported in Figure 5.5 is the maximum 98th percentile and the mean reported in Figure 5.6 is the maximum arithmetic mean for the county.)
Figure 5.7 is a map of “design values” for PM2.5, computed from the highest 3-year average arithmetic mean in each county for 2006 through 2008, using the federal reference method monitors. Thirty-one counties have enough reported data to compute this metric correctly, and two appear to be violating the ambient standard Catawba and Davidson. Attainment decisions for PM2.5 will be based on the design values observed during 2006 through 2008. 22
Figure 5.4 Location of PM2.5 Monitoring Sites
Table 5.3 PM2.5 in Micrograms Per Cubic Meter for 2008
SITE NUMBER
ADDRESS
NUM
OBS
24-HOUR MAXIMA
PERCENTILE
ARITH
MEAN
COUNTY
1st
2nd
3rd
4th
98TH
37-001-0002
ALAMANCE
827 S. GRAHAM & HOPEDALE RD
88
25.7
25.7
23.2
21.7
25.7
12.70
BURLINGTON
37-021-0034
BUNCOMBE
175 BINGHAM ROAD
ASHEVILLE
86
30.2
29.9
23.2
19.2
29.9
9.92
37-033-0001
CASWELL
7074 CHERRY GROVE RECREATION
45
24.0
22.7
21.5
19.7
24.0
12.03
37-035-0004
1650 1ST. ST.
234
31.5
28.5
27.7
26.7
25.6
13.50
CATAWBA
HICKORY
37-037-0004
325 RUSSETT
80
71.7
27.7
23.0
22.6
27.7
12.73
CHATHAM
PITTSBORO
37-051-0009
CUMBERLAND
4533 RAEFORD ROAD
85
29.3
24.2
23.7
23.2
24.2
12.70
FAYETTEVILLE
37-057-0002
DAVIDSON
SOUTH SALISBURY STREET
91
28.4
25.2
24.7
24.7
25.2
14.29
LEXINGTON
37-061-0002
HWY 50
82
24.9
21.8
20.4
19.6
21.8
11.02
DUPLIN
KENANSVILLE
37-063-0015
801 STADIUM DR
92
23.7
23.3
22.7
22.5
23.3
12.12
EDGECOMBE
ROCKY MOUNT
23
SITE NUMBER
ADDRESS
NUM
OBS
24-HOUR MAXIMA
PERCENTILE
ARITH
MEAN
COUNTY
1st
2nd
3rd
4th
98TH
37-065-0004
900 SPRINGFIELD
89
32.2
29.9
24.1
23.0
29.9
11.89
EDGECOMBE
ROCKY MOUNT
37-067-0022
FORSYTH
1300 BLOCK, HATTIE AVENUE
239
60.8
26.7
26.7
26.6
26.1
12.97
WINSTON-SALEM
37-067-0030
FORSYTH
FRATERNITY CHURCH ROAD
87
26.2
25.2
24.4
24.1
25.2
13.17
WINSTON-SALEM
37-071-0016
GASTON
1622 EAST GARRISON BLVD
92
25.5
25.3
22.8
22.7
25.3
13.34
GASTONIA
37-081-0013
GUILFORD
205 WILOUGHBY BLVD
249
68.6
28.8
27.0
26.7
25.0
12.44
GREENSBORO
37-081-0014
HAYWOOD
2127 SANDY RIDGE ROAD
91
31.3
29.0
24.1
22.3
29.0
13.30
WAYNESVILLE
37-087-0012
HAYWOOD
550 VANCE STREET
WAYNESVILLE
89
31.0
25.1
24.6
24.5
25.1
12.02
37-099-0006
US RT 19 NORTH
83
31.8
24.1
23.6
22.7
24.1
10.22
JACKSON
CHEROKEE
37-107-0004
LENOIR
CORNER HWY 70 EAST
88
38.3
21.5
20.9
20.6
21.5
11.06
KINSTON
37-111-0004
BALDWIN AVE
88
28.6
27.9
25.4
24.6
27.9
12.35
MC DOWELL
MARION
37-117-0001
1210 HAYES ST
91
91.8
23.7
22.9
22.8
23.7
12.06
MARTIN
JAMESVILLE
37-119-1041
MECKLENBURG
1130 EASTWAY DRIVE
321
29.3
29.1
28.9
27.9
25.1
12.65
CHARLOTTE
37-119-1042
MECKLENBURG
1935 EMERYWOOD DRIVE
111
27.0
24.3
23.3
22.5
23.3
13.14
CHARLOTTE
37-119-0043
MECKLENBURG
513 RADIO ROAD
CHARLOTTE
323
29.2
28.2
27.5
27.1
26.2
12.35
37-121-0001
MITCHELL
CITY HALL SUMMIT ST
87
25.8
21.1
19.3
17.4
21.1
10.79
SPRUCE PINE
37-123-0001
112 PERRY DRIVE
90
22.3
22.2
22.0
21.2
22.2
12.16
MONTGOMERY
CANDOR
37-129-0002
NEW HANOVER
6028 HOLLY SHELTER RD
16
41.6
15.2
14.4
12.3
41.6
10.44
24
SITE NUMBER
ADDRESS
NUM
OBS
24-HOUR MAXIMA
PERCENTILE
ARITH
MEAN
COUNTY
1st
2nd
3rd
4th
98TH
37-135-0007
ORANGE
MASON FARM ROAD
90
25.1
24.3
23.0
22.7
24.3
12.12
CHAPEL HILL
37-147-0005
PITT
851 HOWELL STREET
87
107.6
23.5
23.2
22.8
23.5
12.47
GREENVILLE
37-147-0006
PITT
403 GOVERNMENT
CIRCLE
59
72.9
33.8
23.0
22.6
33.8
13.39
37-155-0005
ROBESON
1170 LINKHAM ROAD
88
23.7
22.5
22.2
22.0
22.5
12.09
LUMBERTON
37-159-0021
ROWAN
301 WEST ST & GOLD HILL AVE
92
26.4
25.6
25.1
23.6
25.6
13.71
ROCKWELL
37-173-0002
SWAIN
CENTER ST/PARKS 7 REC
88
27.8
23.6
22.6
22.2
23.6
11.93
FACILITY
37-183-0014
WAKE
3801 SPRING FOREST RD
265
99.0
30.5
26.9
26.5
24.6
12.31
RALEIGH
37-183-0020
WAKE
3720 LAKE WHEELER RD
88
27.2
22.7
22.4
22.0
22.7
12.38
37-189-0003
WATAUGA
361JEFFERSON HWY
94
28.2
24.1
18.4
18.2
24.1
10.04
BOONE
37-191-0005
WAYNE
DILLARD MIDDLE SCHOOL
44
36.6
27.9
26.5
23.2
36.6
13.15
GOLDSBORO
Total Samples
3,893
Total Sites Sampled
33
25
Table 5.4 Exceedances of the PM2.5 Standard in 2008
SITE NUMBER
CONCENTRATION
DATE
EXPLANATION
COUNTY
37-037-0004
71.7
06/12
Evans Road Fire, Pocosin Lakes NWR
CHATHAM
37-067-0022
60.8
06/13
Evans Road Fire, Pocosin Lakes NWR
FORSYTH
37-081-0013
GUILFORD
68.6
06/13
Evans Road Fire, Pocosin Lakes NWR
37-107-0004
LENOIR
38.3
06/11
Evans Road Fire, Pocosin Lakes NWR
37-117-0001
MARTIN
91.8
06/05
Evans Road Fire, Pocosin Lakes NWR
37-129-0002
NEW HANOVER
41.6
03/31
Edna Buck Road Fire, New Hanover Co.
37-147-0005
PITT
107.6
06/11
Evans Road Fire, Pocosin Lakes NWR
37-147-0006
PITT
72.9
06/11
Evans Road Fire, Pocosin Lakes NWR
37-183-0014
WAKE
99.0
06/12
Evans Road Fire, Pocosin Lakes NWR
37-191-0005
WAYNE
36.6
06/11
Evans Road Fire, Pocosin Lakes NWR
Total Exceedances
10
Number of Sites with Exceedances
10
Number of Days with
5
Exceedances
26
Figure 5.5 PM2.5: 98th Percentile, 2008
Figure 5.6 PM2.5: Annual Arithmetic Means, 2008 27
Figure 5.7 PM2.5 Design Values by County, 2006-2008
28
5.4 Carbon Monoxide
Carbon monoxide (CO) data were collected for two purposes in 2008: to determine attainment status of the ambient air quality standard, and to gather data on CO as an ozone precursor. The carbon monoxide associated with ozone formation consists of very low concentrations (not greater than 2 ppm) collected at special sites considered optimal for input to a large photochemical grid model. This report will not further discuss the role of CO as an ozone precursor, but these data and more information are available on request from the Division of Air Quality (see the Preface for a mailing address).
To assess CO attainment status, the Division of Air Quality collected data from monitors in Durham, Greensboro and Raleigh, and local program agencies collected data from three monitors in Winston-Salem and Charlotte using EPA Reference or equivalent methods to measure the concentrations.
In 2008, seven sites were used to monitor CO and 41,655 valid hourly averages were collected. The data were collected from monitors:
- Charlotte, Winston-Salem-all year;
- Greensboro, Raleigh
and Fayetteville – colder months.
A map of the CO sampling sites is shown in Figure 5.8, and a detailed summary of the data from each site is presented in Table 5.4.
There were no exceedances of the CO ambient air quality standards in 2008. The highest 1-hour average was 4.0 parts per million (ppm), or about 11 percent of the standard (35 ppm). This value occurred at the Spring Forest Rd. site in
Raleigh (Wake County). The highest 8-hour average was 2.4 ppm, at the Spring Forest Rd. site, which is about 27 percent of the standard. The second highest 1-hour concentrations in each county are shown in Figure 5.9 and the second highest 8-hour concentrations are shown in Figure 5.10.
Historical data have demonstrated that high concentrations of CO occur more frequently in autumn and winter than during the warmer months of the year. There are three main reasons for this seasonal variation: (1) North Carolina experiences more atmospheric inversions in colder months, trapping air pollutants at low heights; (2) motor vehicles emit more CO due to inefficient combustion during cold starts and warm up; and (3) during colder temperatures, more fuel is burned for comfort heating.
All areas monitored are attaining the ambient air quality standards for carbon monoxide. Several factors have reduced CO concentrations, with the most significant being that older vehicles are gradually being replaced with newer,
more efficient vehicles. The motor vehicle Inspection and Maintenance program (in effect in 48 counties [NC Dept of Environmental and Natural Resources, N.D]) is an intentional control strategy that helps assure cleaner-running cars. Other factors include increased news media interest and public awareness, and the reporting of the Air Quality Index (see Chapter 6 of this report). As a result of greater public awareness, more cars are kept in better running condition, thus operating more cleanly. Traffic flow improvements such as new roads and better coordinated traffic signals also help reduce CO.
29
Figure 5.8 Location of Carbon Monoxide Monitoring Sites
Table 5.5 Carbon Monoxide in Parts Per Million for 2008
SITE NUMBER
ADDRESS
NUM
OBS
ONE-HOUR
MAXIMA
EIGHT-HOUR
MAXIMA
COUNTY
1st
2nd
1st
2nd
37-051-0007
ABC BOARD, 1705 OWEN DRIVE
2,044
2.2
2.2
1.7
1.7
CUMBERLAND
FAYETTEVILLE
37-067-0023
1401 CORPORATION PKY
8,725
2.7
2.5
2.3
1.9
FORSYTH
WINSTON-SALEM
37-081-1011
401 WEST WENDOVER
1,985
1.9
1.9
1.6
1.5
GUILFORD
GREENSBORO
37-119-0041
MECKLENBURG
1130 EASTWAY DRIVE
CHARLOTTE
8,665
2.3
2.1
1.9
1.6
37-159-0021
ROWAN
301 WEST ST & GOLD HILL
ROCKWELL
8,085
1.6
1.5
.9
.7
37-183-0014
WAKE
3801 SPRING FOREST RD.
RALEIGH
7,780
4.0
2.8
2.4
1.8
37-183-0018
WAKE
US HWY 70 WEST AND NC HWY 50 NORTH
4,371
3.5
3.1
2.2
2.2
RALEIGH
Total Samples
41,655
Total Sites Sampled
7
30
Figure 5.9 Carbon Monoxide: Second Highest 1-Hour Concentration, 2008
Figure 5.10 Carbon Monoxide: Second Highest Non-overlapping 8-Hour
Concentration, 2008
31
5.5 Ozone
Ozone (O3) concentrations are measured using EPA reference or equivalent continuous monitors. Ozone is a seasonal pollutant formed in the atmosphere as a result of many chemical reactions that occur in sunlight, mainly during the warmer months. Thus, most ozone monitors only operate from April through October.
The state and local program agencies operated 40 monitoring sites in 2008 during the ozone season, April through October. A map of the O3 sampling sites is presented in Figure 5.11, and a detailed summary of the one-hour data from each site is given in Table 5.5, and the 8-hour data in Table 5.6. These 40 monitoring sites provided 8,166 site-days of valid data (a success rate of 95 percent for the days that sampling is required).
The one-hour standard is exceeded when one valid one-hour average exceeds 0.124 ppm at a site and the expected number of exceedances is greater than one. (To exceed the standard, the largest average must be larger than 0.12 ppm when rounded to two significant digits. The “expected number” of exceedances is determined from a 3-year average of exceedance day counts for an area.
There were no exceedances of the 1-hour ozone standard in North Carolina in 2008.
The 8-hour standard is exceeded at the monitoring site when any of the highest daily 8-hour averages in the same calendar year are greater than 0.075 ppm. The 8-hour standard was exceeded
a total of 197 times at the 40 sites that monitored for O3. Thirty-eight monitors had at least one exceedance. The largest number at one monitor was 15
in Charlotte (Mecklenburg County). These exceedances were distributed over 36 days during the ozone season when at least one site within the state recorded values greater than 0.075 ppm. More information about dates and places of these ozone exceedances can be found online in http://www.ncair.org/monitor/data/files/o3data_2008.pdf or http://www.ncair.org/monitor/data/files/o3data_2008.xls .
Moreover, when any ozone sampling day does not have a valid maximum ozone measurement for any reason, the missing day can be counted as an estimated exceedance day under certain circumstances [40 CFR 50 App. J, US
EPA 1993, p. 767-768]. Table 5.5 gives both the actually measured and the estimated number of exceedance days at each site.)
The second highest 1-hour concentrations in each county are shown in Figure 5.12 for areas with one or more monitors active in 2008. Monitors whose second highest 1-hour concentration exceeds 0.124 ppm potentially violate the EPA one-hour standard (although it is no longer in effect in North Carolina).
Historical average fourth-highest 8-hour concentrations of O3 in counties where monitors were operated in 2008 are shown in Figure 5.13. Monitors whose fourth-highest 8-hour ozone concentration (averaged over three years) exceeds 0.084 ppm are deemed in violation of the EPA 8-hour standard.32
Figure 5.11 Location of Ozone Monitoring Sites
Table 5.6 One-Hour Ozone in Parts Per Million for 2008
SITE NUMBER
ADDRESS
NUM
OBS
DAILY 1-HR MAXIMA
NO. VALUES > 0.125
COUNTY
1st
2nd
3rd
4th
MEAS
EST
37-003-0004
106 WAGGIN’ TRAIL
5088
.095
.089
.086
.085
0
0.00
ALEXANDER
TAYLORSVILLE
37-011-0002
AVERY
7510 BLUE RIDGE
LINVILLE
5112
.086
.078
.076
.074
0
0.00
37-021-0030
ROUTE 191 SOUTH BREVARD RD
5136
.090
.080
.080
.080
0
0.00
BUNCOMBE
ASHEVILLE
37-027-0003
HWY 321 NORTH
5136
.085
.083
.078
.077
0
0.00
CALDWELL
LENOIR
33
SITE NUMBER
ADDRESS
NUM
OBS
DAILY 1-HR MAXIMA
NO. VALUES > 0.125
COUNTY
1st
2nd
3rd
4th
MEAS
EST
37-033-0001
7074 CHERRY GROVE
5112
.104
.095
.090
.086
0
0.00
CASWELL
REIDSVILLE
37-037-0004
325 RUSSETT RUN ROAD
5112
.087
.082
.079
.079
0
0.00
CHATHAM
PITTSBORO
37-051-0008
1/4MI SR1857/US301/1857
4968
.091
.089
.087
.086
0
0.00
CUMBERLAND
WADE
37-051-1003
3625 GOLFVIEW ROAD
5016
.086
.086
.085
.083
0
0.00
CUMBERLAND
HOPE MILLS
37-059-0002
246 MAIN STREET
5136
.101
.094
.091
.091
0
0.00
DAVIE
COOLEEMEE
37-063-0015
2700 NORTH DUKE STREET
5136
.092
.089
.086
.082
0
0.00
DURHAM
DURHAM
37-065-0099
7589 NC HWY 33-NW
4968
.091
.089
.085
.083
0
0.00
EDGECOMBE
LEGGETT
37-067-0022
1300 BLK. HATTIE AVENUE
5136
.095
.091
.090
.090
0
0.00
FORSYTH
WINSTON-SALEM
37-067-0028
6496 BAUX MOUNTAIN ROAD
4896
.091
.091
.090
.089
0
0.00
FORSYTH
WINSTON-SALEM
37-067-0030
FRATERNITY CHURCH ROAD
5112
.094
.091
.088
.085
0
0.00
FORSYTH
WINSTON-SALEM
37-067-1008
3656 PIEDMONT MEMORIAL DRIVE
5136
.092
.089
.089
.088
0
0.00
FORSYTH
WINSTON-SALEM
37-069-0001
431 S. HILLBOROUGH ST
5136
.085
.084
.084
.084
0
0.00
FRANKLIN
FRANKLINTON
37-075-0001
FOREST ROAD 423 SPUR
4944
.087
.085
.080
.077
0
0.00
GRAHAM
KILMER
37-077-0001
GRANVILLE
WATER TREATMENT PLANT, JOHN UMSTEAD HOSPITAL
5136
.096
.096
.089
.086
0
0.00
BUTNER
34
SITE NUMBER
ADDRESS
NUM
OBS
DAILY 1-HR MAXIMA
NO. VALUES > 0.125
COUNTY
1st
2nd
3rd
4th
MEAS
EST
37-081-0013
205 WILOUGHBY BLVD
4392
.104
.096
.087
.086
0
0.00
GUILFORD
GREENSBORO
37-087-0004
2177 SCHEVILLS ROAD
5136
.081
.076
.075
.075
0
0.00
HAYWOOD
WAYNESVILLE
37-087-0035
TOWER BLUE RIDGE PARKWAY
4752
.095
.092
.091
.087
0
0.00
HAYWOOD
MILE MARKER 410
37-087-0036
GREAT SMOKY MOUNTAIN
5088
.099
.087
.087
.081
0
0.00
HAYWOOD
NATIONAL PARK
37-101-0002
1338 JACK ROAD
5136
.094
.087
.086
.085
0
0.00
JOHNSTON
CLAYTON
37-107-0004
CORNER HWY EAST
4968
.088
.085
.083
.083
0
0.00
LENOIR
KINSTON
37-109-0004
1487 RIVERVIEW ROAD
5136
.115
.115
.098
.094
0
0.00
LINCOLN
LINCOLNTON
37-117-0001
1210 HAYES STREET
4848
.088
.085
.081
.081
0
0.00
MARTIN
JAMESVILLE
37-119-0041
1130 EASTWAY DRIVE
5136
.118
.113
.112
.097
0
0.00
MECKLENBURG
CHARLOTTE
37-119-1005
400 WESTINGHOUSE BLVD.
5136
.103
.097
.090
.088
0
0.00
MECKLENBURG
CHARLOTTE
37-119-1009
29 N@ MECKLENBURG CAB CO
5136
.113
.109
.106
.101
0
0.00
MECKLENBURG
CHARLOTTE
37-129-0002
6028 HOLLY SHELTER RD
3984
.084
.082
.081
.077
0
0.00
NEW HANOVER
CASTLE HAYNE
37-145-0003
STATE HIGHWAY 49 SOUTH
5040
.091
.086
.085
.085
0
0.00
PERSON
ROXBORO
37-147-0006
403 GOVERNMENT CIRCLE
4944
.089
.089
.087
.081
0
0.00
PITT
GREENVILLE
35
SITE NUMBER
ADDRESS
NUM
OBS
DAILY 1-HR MAXIMA
NO. VALUES > 0.125
COUNTY
1st
2nd
3rd
4th
MEAS
EST
37-157-0099
6371 NC 65 @ BETHANY SCHOOL
5136
.101
.095
.095
.089
0
0.00
ROCKINGHAM
BETHANY
37-159-0021
301 WEST ST & GOLD HILL AVENUE
5136
.110
.102
.101
.099
0
0.00
ROWAN
ROCKWELL
37-159-0022
925 N ENOCHVILLE AVE
5088
.104
.101
.095
.094
0
0.00
ROWAN
CHINA GROVE
37-173-0002
CENTER STREET
5136
.076
.075
.073
.070
0
0.00
SWAIN
BRYSON CITY
37-179-0003
701 CHARLES STREET
5040
.100
.097
.094
.092
0
0.00
UNION
MONROE
37-183-0014
3801 SPRING FOREST ROAD
5112
.091
.089
.086
85
0
0.00
WAKE
RALEIGH
37-183-0016
201 NORTH BROAD STREET
5112
.090
.088
.086
.083
0
0.00
WAKE
FUQUAY-VARINA
37-199-004
YANCY
STATE HIGHWAY 128
BURNSVILLE
3936
.088
.083
.083
.082
0
0.00
Total Samples
199,944
0
0.00
Total Sites Sampled
40
36
Table 5.7 Eight-Hour Ozone in Parts Per Million for 2008
SITE NUMBER
ADDRESS
VALID
DAYS
VALID DAILY 8-HR MAXIMUM
N0. VALUES
COUNTY
.>.085
1st
2nd
3rd
4th
MEAS
37-003-0004
106 WAGGIN’ TRAIL
202
.084
.081
.078
.076
4
ALEXANDER
TAYLORSVILLE
37-011-0002
7510 BLUE RIDGE
207
.079
.072
.071
.070
1
AVERY
37-021-0030
ROUTE 191 SOUTH BREVARD RD
214
.080
.075
.072
.071
1
BUNCOMBE
ASHEVILLE
37-027-0003
HWY 321 NORTH
212
.078
.074
.072
.072
1
CALDWELL
LENOIR
37-033-0001
7074 CHERRY GROVE RD
213
.089
.084
.081
.080
5
CASWELL
REIDSVILLE
37-037-0004
325 RUSSETT RUN
213
.081
.075
.072
.071
1
CHATHAM
PITTSBORO
37-051-0008
1/4MI SR1857/US301/1857
192
.083
.082
.078
.075
3
CUMBERLAND
WADE
37-051-1003
3625 GOLFVIEW ROAD
207
.083
.081
.077
.075
3
CUMBERLAND
HOPE MILLS
37-059-0002
246 MAIN STREET
214
.089
.084
.082
.081
6
DAVIE
COOLEEMEE
37-063-0015
801 STADIUM DRIVE
211
.083
.082
.076
.076
4
DURHAM
DURHAM
37-065-0099
7589 NC HWY 33-NW
201
.082
.081
.078
.075
3
EDGECOMBE
LEGGETT
37-067-0022
1300 BLK. HATTIE AVENUE
214
.087
.083
.083
.081
7
FORSYTH
WINSTON-SALEM
37-067-0028
6496 BAUX MOUNTAIN RD
203
.086
.084
.078
.077
4
FORSYTH
WINSTON-SALEM
37-067-0030
FRATERNITY CHURCH ROAD
213
.090
.081
.081
.078
4
FORSYTH
WINSTON-SALEM
37-067-1008
3656 PIEDMONT MEMORIAL
214
.085
.085
.082
.078
7
FORSYTH
DRIVE
WINSTON-SALEM
37-069-0001
431 S. HILLBOROUGH ST
205
.080
.079
.078
.078
5
FRANKLIN
FRANKLINTON
37-075-0001
FOREST ROAD 423 SPUR
204
.082
.079
.078
.078
4
GRAHAM
KLIMER
37-077-0001
WATER TREATMENT PLANT
213
.085
.082
.081
.081
6
GRANVILLE
JOHN UMSTEAD HOSPITAL
BUTNER
37-081-0013
205 WILOUGHBY
174
.088
.083
.083
.081
5
GUILFORD
GREENSBORO
37-087-0004
2177 SHEVILLE ROAD
213
.078
.071
.070
.070
1
HAYWOOD
WAYNESVILLE
37
SITE NUMBER
ADDRESS
VALID
DAYS
VALID DAILY 8-HR MAXIMUM
N0. VALUES
COUNTY
.>.085
1st
2nd
3rd
4th
MEAS
37-087-0035
TOWER BLUE RIDGE PARKWAY
187
.087
.085
.081
.080
8
HAYWOOD
MILE MARKER 410
37-087-0036
GREAT SMOKY MOUNTAIN
206
.089
.085
.081
.080
5
HAYWOOD
NATIONAL PARK
37-101-0002
1338 JACK ROAD
208
.083
.083
.082
.076
5
JOHNSTON
CLAYTON
37-107-0004
CORNER HWY 70 EAST
206
.079
.075
.074
.074
1
LENOIR
KINSTON
37-109-0004
1487 RIVERVIEW ROAD
208
.097
.093
.086
.079
9
LINCOLN
LINCOLNTON
37-117-0001
1210 HAYES STREET
193
.083
.081
.075
.074
2
MARTIN
JAMESVILLE
37-119-0041
1130 EASTWAY DRIVE
214
.101
.098
.095
.085
10
MECKLENBURG
CHARLOTTE
37-119-1005
400 WESTINGHOUSE BLVD.
214
.095
.079
.075
.073
2
MECKLENBURG
CHARLOTTE
37-119-1009
29 N@ MECKLENBURG CAB CO
210
.096
.095
.094
.093
15
MECKLENBURG
CHARLOTTE
37-129-0002
6028 HOLLY SHELTER RD
154
.070
.070
.068
.063
0
NEW HANOVER
37-145-0003
STATE HIGHWAY 49 SOUTH
204
.083
.080
.079
.078
5
PERSON
ROXBORO
37-147-0006
403 GOVERNMENT CIRCLE
203
.084
.083
.079
.077
4
PITT
GREENVILLE
37-157-0099
6371 NC 65 @ BETHANY SCHOOL
212
.090
.088
.084
.084
10
ROCKINGHAM
BETHANY
37-159-0021
301 WEST ST & GOLD HILL AVE
198
.095
.091
.087
.084
11
ROWAN
ROCKWELL
37-159-0022
925 N ENOCHVILLE AVE
212
.087
.086
.083
.082
10
ROWAN
ENOCHVILLE
37-173-0002
CENTER STREET
210
.070
.068
.068
.067
0
SWAIN
PARKS 7 REC FACILITY
37-179-0003
701 CHARLES STREET
209
.090
.081
.080
.080
10
UNION
MONROE
37-183-0014
E. MILLBROOK JR HI
211
.080
.080
.079
.078
4
WAKE
3801 SPRING FOREST ROAD
37-183-0016
201 NORTH BROAD STREET
208
.085
.079
.078
.078
7
WAKE
FUQUAY-VARINA
37-199-0004
NEW LOC MT MITCHELL
160
.080
.079
.079
.078
4
YANCEY
BURNSVILLE
Total Samples
8,166
197
Total Sites Sampled
40
38
Figure 5.12 Ozone: Second Highest Annual 1-Hour Average, 2008
Figure 5.13 Ozone: Mean Annual Fourth Highest 8-Hour Average, 2006-2008
39
5.6 Sulfur Dioxide
Sulfur dioxide (SO2) concentrations were measured by the state and two local program agencies using EPA reference or equivalent methods. Eight SO2 monitors were active in North Carolina in 2008. Some SO2 sites are operated only every third year. We supplemented this report with one monitor that operated last in 2007, (and will next be operated in 2010), and one monitor that operated last in 2006 (and will next be operated in 2009).
From the 10 sites with SO2 data obtained between 2006 and 2008, 73,953 valid hourly averages were collected. A map of the active SO2 sampling sites is presented in Figure 5.14 and a detailed summary of the data from each site is given in Table 5.7.
There were no exceedances of the SO2 ambient air quality standards in 2008. The highest annual arithmetic mean was
6.24 ppb, or about 21 percent of the standard (0.03 ppm). The highest maximum 24-hour average was 28.2 ppb, about 20 percent of the standard (0.14 ppm).
Apparently, the size of an urban area has little effect on the ambient concentrations of SO2 in North Carolina. Seasonal variations, such as those with CO and O3, do not appear to exist for SO2. Major source characteristics such as type, size, distribution, control devices, operating conditions and dispersion situations significantly affect the amount of SO2 in ambient air.
The second highest one-hour concentrations in each county are shown in Figure 5.15. The second highest 24-hour concentrations in each county are shown in Figure 5.16.
40
Figure 5.14 Locations of Sulfur Dioxide Monitoring Sites in 2006, 2007 and 2008
Table 5.8 Sulfur Dioxide in Parts Per Billion from All Sites for 2006-2008
SITE NUMBER
ADDRESS
NUM OBS
ONE-HOUR MAXIMA
24-HOUR MAXIMA
ARITH MEAN
COUNTY
1st
2nd
1st
2nd 2008 37-013-0007 1645 SANDY LANDING 8,045 49.0 43.0 10.4 9.4 .88 BEAUFORT AURORA 37-037-0004 325 RUSSETT RUN ROAD 8,332 40.0 25.0 8.7 6.2 1.62 CHATHAM WINSTON-SALEM 37-067-0022 1300 BLK. HATTIE AVE 8,548 56.0 37.0 12.6 11.9 6.24 FORSYTH WINSTON-SALEM 37-119-0041 MECKLENBURG 1130 EASTWAY DRIVE CHARLOTTE 8,679 96.3 88.6 15.3 13.1 2.09 37-129-0006 HIGHWAY 421 NORTH 8,081 168.0 143.0 28.2 27.9 5.19 NEW HANOVER WILMINGTON 37-173-0002 SWAIN 30 RECREATION PARK DRIVE 197 3.0 3.0 1.7 1.0 .54 BRYSON CITY 37-183-0014 WAKE 3801SPRING FOREST RD. RALEIGH 8,131 17.0 17.0 9.4 7.7 1.38
Total Samples
50,013
Total Sites Sampled
7
41
SITE NUMBER
ADDRESS
NUM OBS
ONE-HOUR MAXIMA
24-HOUR MAXIMA
ARITH MEAN
COUNTY
1st
2nd
1st
2nd 2007 37-117-0001 MARTIN 1210 HAYES STREET JAMESVILLE 8,225 19.0 18.0 8.0 6.0 1.6 37-117-0002 MARTIN 33215 US HIGHWAY 64 7,453 40.0 30.0 10.0 8.0 2.0
Total Samples
15,678
Total Sites Sampled
2
2006 37-051-1003 3625 GOLFVIEW RD 8,262 20.0 19.0 7.0 7.0 2.2 CUMBERLAND HOPE MILLS
Total Samples
8,262
Total Sites Sampled
1
42
Figure 5.15 Sulfur Dioxide: Second Highest 1-Hour Averages in the Most Recent Year of Data from 2006, 2007 or 2008
Figure 5.16 Sulfur Dioxide: Second Highest 24-Hour Averages in the Most Recent Year of Data from 2006, 2007 or 200843
5.7 Nitrogen Dioxide
Nitrogen dioxide (NO2) concentrations were measured using EPA reference or equivalent continuous monitors in 2008 at one local program site in Forsyth County and one local program site in Mecklenburg County.
From these two sites, 16,962 hourly NO2 measurements were reported. A map of the NO2 sampling sites is presented in Figure 5.17, and a summary of the 2008 NO2 data is given in Table 5.8.
Each urban area site has only a few outlying high hourly sample values that are above the standard defined for the annual arithmetic mean. The arithmetic means (Table 5.8) are about 21 percent of the standard.
Figure 5.17 Location of Nitrogen Dioxide Monitoring Sites
Table 5.9 Nitrogen Dioxide in Parts Per Billion for 2008
SITE NUMBER
ADDRESS
NUM OBS
ONE-HOUR MAXIMA
ARITH MEAN
COUNTY
1ST
2ND
37-067-0022
1300 BLK. HATTIE AVENUE
8,376
61.0
61.0
11.10
FORSYTH
WINSTON-SALEM
37-119-0041
1130 EASTWAY DRIVE
8,586
59.0
58.0
11.16
MECKLENBURG
CHARLOTTE
Total Samples
16,962
Total Sites Sampled
2
44
5.8 Lead
The state and local program agencies have not performed routine analysis of ambient lead (Pb) in North Carolina since 1982. Lead monitoring was discontinued as a result of the low measurements and a continuing decrease in the lead concentrations being reported. The decrease in ambient Pb concentrations is due to the reduction and elimination of leaded gasoline, resulting in greatly reduced lead emissions from automobiles.
5.8.1 Special Studies
The most recent year of data available prior to 1996-97 was in 1990. Because the previous data were so old, the state began metals analysis at three locations in 1996. These metal sites will be relocated to other locations in future years. The purpose of these sites is to gather background information about lead and other metals. No lead sites operated in 2008.
The change in analytical laboratories from the EPA‟s National Particulate Analysis Program to the state program also changed the minimum detectable levels of the method from 0.01 to 0.04 g/m3, respectively. Concentrations of most metals are below detectable limits regardless of the method used.
During 1999 and 2000, a special study focusing on arsenic levels was undertaken. Lead, and other toxic metals were sampled on filters using the TSP Reference Method at selected ambient air monitoring sites, by a contract laboratory using inductively coupled plasma/mass spectrometry (ICP/MS). This method can detect sample concentrations of lead as small as 0.01 nanograms (0.00001 g) per cubic meter.
Of the 526 valid samples analyzed in 1999 only 18 exceeded the Reference Method‟s detection limits. Only one sample exceeded 0.04 g/m3, and 17 others exceeded 0.01 g/m3.
45
6 Air Quality Index
The Air Quality Index (AQI) was developed by the EPA to provide the public with a simple, accessible, and uniform assessment of air quality at a specific location, based on the criteria pollutants PM2.5, PM10, CO, O3 (both 1 and 8 hour values), SO2 and NO2. AQI measurements are made and reported in all U.S. metropolitan statistical areas (MSA) with a population over 350,000. Ambient concentrations for each of these seven pollutants are converted to a numerical scale ranging from 0 to 500, where 100 corresponds to the EPA primary standard for a 24-hour average (8-hour CO average, 1 and 8-hour O3 average) and 500 corresponds to a concentration associated with significant harm. The AQI is determined by the pollutant with the highest scaled concentration, and a subjective description of good, moderate, “unhealthy for sensitive groups”, “unhealthy”, very unhealthy, or hazardous is included with the report, with the descriptions corresponding to AQI values of 0-50, 51-100, 101-150, 151-200, 201-300, and 301-500, respectively. For AQI values between 101 and 500, an appropriate cautionary statement is included advising people susceptible to deleterious health effects to restrict activities and exposure to the ambient air.
An AQI of 101-200 (unhealthy for sensitive groups and unhealthy) can produce mild aggravation of symptoms
in susceptible persons and possible irritation in healthy persons. People with existing heart or lung ailments should
reduce physical exertion and outdoor activity. The general population should reduce vigorous outdoor activity.
An AQI of 201 to 300 (very unhealthy) can produce significant aggravation of symptoms and decreased exercise tolerance in persons with heart or lung disease, and a variety of symptoms in healthy persons. Elderly people and those with existing heart or lung disease should stay indoors and reduce physical activity. The general population should avoid vigorous outdoor activity.
The health effects of an AQI of over 300 (hazardous) include early onset of certain diseases in addition to significant aggravation of symptoms and decreased exercise tolerance in healthy persons. The elderly and persons with existing diseases should stay indoors and avoid physical exertion.
At AQI values over 400, premature death of ill and elderly persons may result, and healthy people will experience adverse symptoms that affect normal activity. Outdoor activity should be avoided. All people should remain indoors, keeping windows and doors closed, and should minimize physical exertion.
46
During summer months in North Carolina the highest air quality index value tends to be attributed to ozone, but during winter months PM2.5 predominates, except where carbon monoxide monitors are operated.
In 2008, Charlotte area provided an AQI report to the public by telephone using computer- generated recorded voice announcements 24 hours daily. The AQI report also may be published by local newspapers or broadcast on radio and television stations.
The Air Quality Index report is available by telephone for Charlotte area at 704-333-SMOG. We also provide an AQI Report on the North Carolina DAQ web site,
(http://www.daq.state.nc.us/monitor).
In this printed report, we have summarized AQI statistics for six metropolitan areas in North Carolina. Table 6.1 shows the number of days in each health category at each area.
In the Ashville MSA, the AQI was “unhealthy for sensitive groups” or “unhealthy” on one out of 364 days monitored. This day occurred in July.
Figure 6.1 shows the 2008 AQI time series for Asheville. Figure 6.2 shows summaries of the numbers of days each respective pollutant was responsible for the AQI, the number of days the AQI was in each respective health category, and the percentile distribution for each health category for Asheville.
In the Charlotte-Gastonia-Rock Hill MSA, the AQI was “unhealthy for sensitive groups” or “unhealthy” on 31 out of 366 days monitored. All 31 of these days occurred between April and September.
Figure 6.3 shows the 2008 AQI time series for Charlotte-Gastonia-Rock Hill. Figure 6.4 shows summaries of the numbers of days each respective pollutant was responsible for the AQI, the number of days the AQI was in each respective health category, and the percentile distribution for each health category for Charlotte-Gastonia-Rock Hill.
In the Fayetteville MSA, the AQI was “unhealthy for sensitive groups” or “unhealthy” on three out of 363 days monitored. All three of these days occurred between April and July.
Figure 6.5 shows the 2008 AQI time series for Fayetteville. Figure 6.6 shows summaries of the numbers of days each respective pollutant was responsible for the AQI, the number of days the AQI was in each respective health category, and the percentile distribution for each health category for Fayetteville.
In the Greensboro-Winston-Salem-High Point MSA, the AQI was “unhealthy for sensitive groups” or “unhealthy” on 12 out of 366 days monitored. All 12 of these days occurred between April and July.
Figure 6.7 shows the 2008 AQI time series for Greensboro- Winston-Salem-High Point. Figure 6.8 shows summaries of the numbers of days each respective pollutant was responsible for the AQI, the number of days the AQI was in each respective health category, and the percentile distribution for each health 47
category for Greensboro-Winston-Salem-High Point.
In the Raleigh-Durham-Chapel Hill MSA, the AQI was “unhealthy for sensitive groups” or “unhealthy” on 12 out of 366 days monitored. All 12 of these days occurred between April and September.
Figure 6.9 shows the 2008 AQI time series for Raleigh-Durham-Chapel Hill. Figure 6.10 shows summaries of the numbers of days each respective pollutant was responsible for the AQI, the number of days the AQI was in each respective health category, and the percentile distribution for each health category for Raleigh-Durham-Chapel Hill.
In the Wilmington MSA, the AQI was “unhealthy for sensitive groups” or “unhealthy” on 15 out of 364 days monitored. All 15 of these days occurred between January and November.
Figure 6.11 shows the 2008 AQI time series for Wilmington. Figure 6.12 shows summaries of the numbers of days each respective pollutant was responsible for the AQI, the number of days the AQI was in each respective health category, and the percentile distribution for each health category for Wilmington.
Table 6.1 Air Quality Index Category Days in the Major Metropolitan Statistical Areas, 2008
MSA
STATISTICALTREATMENT
GOOD
MODERATE
UNHEALTHY FOR SENSITIVE GROUPS
UNHEALTHY
Asheville
actual
285
78
1
0
Charlotte
actual
194
141
28
3
Fayetteville
actual
250
110
3
0
Greensboro
actual
197
157
11
1
Raleigh
actual
228
126
11
1
Wilmington
actual
247
102
15
0
48
Figure 6.1 Daily Air Quality Index Values for Asheville
Figure 6.2 Daily Air Quality Index Summary for Asheville
Days Per Main Pollutant
0
50
100
150
200
250
300
CO NO2 O3 PM10 PM2.5 SO2
Days Per Health Category
0
50
100
150
200
250
300
Go o d Mo dera te UnhealthySens itive Unhealthy Very Unhealthy Hazardo us
49
Figure 6.3 Daily Air Quality Index Values for Charlotte-Gastonia
Figure 6.4 Daily Air Quality Index Summary for Charlotte-Gastonia
Days Per Main Pollutant
0
20
40
60
80
100
120
140
160
180
200
CO NO2 O3 PM10 PM2.5 SO2
Days Per Health Category
0
50
100
150
200
250
Go o d Mo dera te UnhealthySens itive Unhealthy Very Unhealthy Hazardo us
50
Figure 6.5 Daily Air Quality Index Values for Fayetteville
Figure 6.6 Daily Air Quality Index Summary for Fayetteville
Days Per Main Pollutant
0
50
100
150
200
250
CO NO2 O3 PM10 PM2.5 SO2
Days Per Health Category
0
50
100
150
200
250
300
Go o d Mo dera te UnhealthySens itive Unhealthy Very Unhealthy Hazardo us
51
Figure 6.7 Daily Air Quality Index Values for Greensboro-Winston-Salem-High Point
Figure 6.8 Daily Air Quality Index Summary for Greensboro-Winston-Salem-High Point
Days Per Main Pollutant
0
50
100
150
200
250
CO NO2 O3 PM10 PM2.5 SO2
Days Per Health Category
0
50
100
150
200
250
Go o d Mo dera te UnhealthySens itive Unhealthy Very Unhealthy Hazardo us
52
Figure 6.9 Daily Air Quality Index Values for Raleigh-Durham-Chapel Hill
Figure 6.10 Daily Air Quality Index Summary for Raleigh-Durham-Chapel Hill
Days Per Main Pollutant
0
50
100
150
200
250
CO NO2 O3 PM10 PM2.5 SO2
Days Per Health Category
0
50
100
150
200
250
Go o d Mo dera te UnhealthySens itive Unhealthy Very Unhealthy Hazardo us
53
Figure 6.11 Daily Air Quality Index Values for Wilmington
Figure 6.12 Daily Air Quality Index Summary for Wilmington
Days Per Main Pollutant
0
50
100
150
200
250
300
CO NO2 O3 PM10 PM2.5 SO2
Days Per Health Category
0
50
100
150
200
250
300
Go o d Mo dera te UnhealthySens itive Unhealthy Very Unhealthy Hazardo us
54
7 Acid Rain and Atmospheric Mercury
7.1 Sources
Acid rain is produced when nitrate and sulfate ions from automobile and industrial sources are released into the atmosphere, undergo a reaction with moisture in the air, and are deposited as acid precipitation. Acid ions are produced when sulfur dioxide and nitrogen oxides react with water to form sulfuric acid and nitric acid.
Atmospheric mercury is a by-product of coal-fire combustion, municipal and medical incineration, and mining of metals for industry, among other processes. Natural sources of atmospheric mercury include outgassing from volcanoes and geothermal vents, and evaporation from naturally enriched soils, wetlands, and oceans.
7.2 Effects
Many agricultural crops in North Carolina are sensitive to acid rain. Forests are subject to mineral loss from acid rain exposure and may also suffer root damage. Acid fogs and mists, typical in the mountains of North Carolina, can expose trees and plants to even higher acid concentrations and cause direct damage to foliage. Lakes, rivers and streams that are too acidic can impede fish and plant growth.
Mercury persists in the environment for long periods (especially in the chemical form of methyl mercury), eventually
accumulating in soils and sediments. It is converted to organic forms by bacteria and then consumed in the aquatic food chain, through which it reaches fish, birds, wildlife and humans. The most important health concern is neurotoxicity. Methyl mercury can contaminate all tissues of the human body. The EPA considers methyl mercury and mercuric chloride to be possible carcinogens (NADP 2005)
7.3 Monitoring
Acid rain monitoring has been conducted nationally, including in North Carolina, since 1978 by the National Atmospheric Deposition Program (NADP) and the National Trends Network (NTN) which merged with NADP in 1982. In 2008, acid rain samples were collected at eight sites in North Carolina and one Tennessee site in the Great Smoky Mountains less than 10 miles from the western border of North Carolina.
NADP conducts acid deposition monitoring using a wet/dry bucket type sampler. When rainfall is detected, a sensor is activated and a metal lid automatically covers and protects the dry sample, exposing the wet bucket to collect precipitation.
The NADP also administers a mercury deposition network (MDN). The MDN began measuring mercury in 55
precipitation in 1996. In 2006 and 2008 mercury deposition samples were obtained from two MDN sites in the eastern coastal area of NC, one at Candor in the Sandhills region and one Tennessee site in the Great Smoky Mountains National Park. The Candor site was not operated in 2008. Figure 7.2 shows locations of the monitors.
Acidity is measured using a pH scale. The pH scale is numbered from 0 to 14, with 0 being extremely acidic and 14 being extremely basic. A substance with a pH of five is 10 times as acidic as one with a pH of six, 100 times as acidic as a substance with a pH of seven, etc. Neutral water with an equal concentration of acid and base ions has a pH of seven. The pH of vinegar is approximately 2.8, and lemon juice has a pH of about 2.3. The pH of ammonia is approximately 12.
Pure water in equilibrium with the air is slightly acidic and has a pH of approximately 5.6. The measurements of pH at the North Carolina monitoring sites in 2008 ranged from 4.74 to 5.07 with a mean of 4.87. The 2008 pH annual means for North Carolina from the NADP database are presented in Figure 7.1 and Table 7.1. Table 7.1 also exhibits conductivity averages and precipitation totals for rainfall. Measured concentrations of several other chemical constituents of precipitation are given in Table 7.2.
The highest pH (and the least acidic) precipitation occurred at the Sampson County site. This general area in southeastern North Carolina has the greatest numbers of animal producing farms. This area has the highest emissions of ammonia, a basic gas emitted from animal wastes.
Table 7.2 shows that the ammonium concentration in precipitation is the highest at the Sampson County site.
Table 7.3 shows precipitation-weighted mercury deposition totals for 2006-2008. Another publication by the NCDAQ, the Annual Air Toxics Report (NCDENR, 2010), shows a time series graph of mercury deposition rates per week for a longer series of years.
Figure 7.1 Annual Mean pH Values at North Carolina NADP Sites, 2008 56
Table 7.1 pH, Conductivity in Microsiemans per Centimeter and Precipitation in Inches from the National Atmospheric Deposition Program for 2008.
County
Site ID
Address
pH
Conductivity
Precipitation
Bertie
NC03
Lewiston
4.86
11.40
37.86
Carteret
NC06
Beaufort
4.87
13.84
55.65
Macon
NC25
Coweeta
4.87
9.0
55.82
Rowan
NC34
Piedmont Research Station
4.74
12.22
42.31
Sampson
NC35
Clinton Crops Research Station
5.07
10.84
55.31
Scotland
NC36
Jordan Creek
4.79
10.31
55.59
Wake
NC41
Finley Farm
4.94
10.13
41.73
Yancey
NC45
Mt. Mitchell
4.84
8.2
46.89
Sevier (TN)
TN11
Great Smoky Mountains National Park-Elkmont
4.84
9.07
57.18
57
Table 7.2 Ion Concentrations in Milligrams per Liter (Precipitation-weighted Annual Means) from the National Atmospheric Deposition Program Data for 2008.
County
Site ID
% Complete-ness
Ca
Mg
K
Na
NH4
NO3
Cl
SO4
Bertie
NC03
94
0.084
0.038
0.037
0.293
0.295
0.747
0.515
1.033
Beaufort
NC06
85
0.104
0.105
0.041
0.890
0.131
0.544
1.613
0.930
Macon
NC25
90
0.091
0.020
0.020
0.132
0.137
0.518
0.237
0.826
Rowan
NC34
96
0.086
0.024
0.047
0.137
0.303
0.778
0.255
1.266
Sampson
NC35
96
0.070
0.039
0.057
0.296
0.518
0.607
0.537
1.179
Scotland
NC36
77
0.064
0.020
0.021
0.141
0.203
0.599
0.255
0.932
Wake
NC41
92
0.067
0.026
0.077
0.205
0.341
0.654
0.369
1.004
Yancey
NC45
37
0.052
0.012
0.010
0.076
0.128
0.406
0.144
0.742
Sevier (TN)
TN11
81
0.123
0.016
0.027
0.051
0.145
0.620
0.090
0.869
58
Figure 7.2 Location of Mercury Monitoring Sites
Table 7.3 Precipitation-weighted mercury deposition in total nanograms per square meter per year for 2006- 2008.
County
Site ID
Address
2006
2007
2008
Columbus
NC08
Waccamaw State Park
8.44
9.17
7.52
Montgomery
NC26
Candor
7.90
8.72
-
Washington
NC42
Pettigrew State Park
6.65
7.69
8.31
Sevier (TN)
TN11
Great Smoky Mountains National Park
Elkmont
8.81
9.62
7.82
59
8. Fine Particle Speciation
8.1 Description of pollutants
The main species or constituents of fine particles are classified as nitrates, sulfates, ammonium, organic carbon, elemental carbon, and crustal components (dust). These account for 75 to 85 percent of the composition of fine particles.
8.1.1 Nitrate
Ammonium nitrate (NH4NO3) is the most abundant nitrate compound, resulting from a reversible gas/particle equilibrium between ammonia gas (NH3), nitric acid gas (HNO3), and particulate ammonium nitrate. Sodium nitrate (NaNO3) is found in PM2.5 and PM10 near sea coasts and salt playas (e.g., Watson et al., 1995a) where nitric acid vapor irreversibly reacts with sea salt (NaCl).
8.1.2 Sulfate
Ammonium sulfate ((NH4)2SO4), ammonium bisulfate (NH4HSO4), and sulfuric acid (H2SO4) are the most common forms of sulfate found in atmospheric particles, resulting from conversion of gases to particles as described below. These compound are water-soluble and reside almost exclusively in the PM2.5 size fraction. Sodium sulfate (Na2SO4) may be found in coastal areas where sulfuric acid has been neutralized by sodium chloride
(NaCl) in sea salt. Though gypsum (Ca2SO4) and some other geological
compounds contain sulfate, these are not easily dissolved in water for chemical analysis, are more abundant in PM10 than in PM2.5, and they are usually classified in the geological fraction.
8.1.3 Ammonium
Ammonium sulfate ((NH4)2SO4), ammonium bisulfate (NH4HSO4), and ammonium nitrate (NH4NO3) are the most common compounds containing ammonium.
8.1.4 Organic Carbon
Particulate organic carbon consists of hundreds, possibly thousands, of separate compounds with more than 20 carbon atoms. Because of this lack of molecular specificity and the semi-volatile nature of many carbon compounds with 20 to 40 carbon atoms, particulate “organic carbon” is operationally defined by the sampling and analysis method.
8.1.5 Elemental Carbon
Elemental carbon is black, often called “soot.” Elemental carbon contains pure, graphitic carbon, but it also contains high molecular weight, dark-colored, non-volatile organic materials such as tar, biogenic, and coke. 60
8.1.6 Crustal Component (Fine Dust)
Suspended dust consists mainly of oxides of aluminum, silicon, calcium, titanium, iron, lead and other metal oxides (Chow and Watson, 1998). The precise combination of these minerals depends on the geology of the area and industrial processes such as steel-making, smelting, mining, and cement production. Geological material is mostly in the coarse particle fraction, and typically constitutes about 50 percent of PM10 while only contributing 5 to 15 percent of PM2.5 (Chow and Watson, 1998).
Lead is a toxic metal that was used for many years in products found in and around homes. Lead also is emitted into the air from motor vehicles and industrial sources. Lead may cause a range of health effects, from behavioral problems and learning disabilities, to seizures and death. The DAQ monitored lead as a federal criteria pollutant in the past (see chapter 5) until it become undetectable by the prescribed sampling method*. For these reasons we include concentration of the lead in PM2.5 in this report.
8.1.7 “Other” Speciated components.
We categorize the 15 to 25 percent of PM2.5 not accounted for by nitrate, sulfate, ammonium, carbon and crustal components as “other” speciated data.
For the purpose of this report “other” is not defined in terms of any certain kind of particulate matter, but is simply the
* EPA promulgated a new lead standard in 2008, and DAQ anticipates establishing a reporting network for it in 2011.
result of subtracting all the other components from the total PM2.5 reported by the sampler. Among the constituents of “other” are liquid water and many trace chemical elements.
8.2 Sources
Sources of fine particles include all types of combustion activities (motor vehicles, power plants, wood burning, etc.) and certain industrial processes. Other particles may be formed in the air from the chemical reactions of gases. They are indirectly formed when gases from burning fuels react with sunlight and water vapor. These can result from fuel combustion in motor vehicles, at power plants, and in other industrial processes.
Particles emitted directly from a source may be either fine (less than 2.5 m) or larger (2.5 - 60 m), but particles photo-chemically formed in the atmosphere will usually be fine. Generally, larger particles have very slow settling velocities and are characterized as suspended particulate matter. Typically, fine particles originate by condensation of materials produced during combustion or atmospheric reactions.
Fine particles also form from the reaction of gases or droplets in the atmosphere from sources such as power plants. These chemical reactions can occur miles from the original source of the emissions. Because fine particles can be carried long distances from their source, events such as wildfires or volcanic eruptions can raise fine particle concentrations hundreds of miles from the event. 61
PM2.5 is also produced by common indoor activities. Some indoor sources of fine particles are tobacco smoke, cooking (e.g., frying, sautéing, and broiling), burning candles or oil lamps, and operating fireplaces and fuel-burning space heaters (e.g., kerosene heaters).
Particles and ozone are similar in many respects. Both can cause respiratory symptoms and other serious health problems. Fossil fuel combustion is a leading source of both pollutants. One significant difference is that particles can be a problem at any time of year, unlike ozone, which forms in warm, sunny weather and therefore tends to be seasonal in nature.
8.3 Effects
The size of the particles is what is most important from a public health viewpoint. Particles larger than 10 m generally get caught in the nose and throat, never entering the lungs. Particles smaller than 10 m can get into the large upper branches just below your throat where they are caught and removed (by coughing and spitting or by swallowing). Particles smaller than 5 m can get into your bronchial tubes, at the top of the lungs; particles smaller than 2.5 m in diameter can get down into the deepest (alveolar) portions of your lungs where gas exchange occurs between the air and your blood stream, oxygen moving in and carbon dioxide moving out. These are the really dangerous particles because the deepest (alveolar) portions of the lung have no efficient mechanisms for removing them. If these particles are soluble in water, they pass directly into the blood stream within minutes. If they are not soluble in water, they are retained in the deep lung for long periods (months or years). About 60 percent of PM10 particles (by weight) have a diameter of 2.5 m or less. These are the particles that can enter the human lung directly.
8.4 Monitoring
The MetOne SASS monitor measures PM2.5 mass and the chemical composition of PM2.5 (sulfates, nitrates, organic carbon, soot-like carbon and metals). This is known as PM2.5 chemical speciation. The MetOne SASS utilizes five independent channels (the Met One Super SASS utilizes eight independent channels) with spiral impactors attached directly to the filter cartridges that are arrayed in a raised carousel. Each canister has its own PM2.5 inlet and Federal Reference Method/Monitor filter holders. The PM2.5 separation is produced by a sharp cut cyclone that removes both solid and liquid coarse particles with equal efficiency without the use of impaction grease or oil.
The Interagency Monitoring of Protected Visual Environments (IMPROVE) is a cooperation between federal land managers, state and local agencies and EPA to collect aerosol particulate data.
IMPROVE sites use a different monitoring method. The standard IMPROVE sampler has four modules: (1) PM2.5 mass, (2) sulfate, nitrate and chloride, (3) PM2.5 quartz and (4) PM10 mass.
Data are validated on a monthly basis when reports are received from the contract laboratory RTI International.
NCDAQ collected data at ten sites using MetOne SASS method, the National Park Service collected at three sites during 2008 using the IMPROVE method. Figure 8.1 shows a map of all 62
these sites. Table 8.1 identifies the sites and the specific sampling methods employed at each one.
Nitrate samples in 2008 are summarized in Table 8.2 and 8.3. The highest concentration observed was 5.32 g/m3 at Kinston.
Sulfate samples in 2008 are summarized in Table 8.4 and 8.5. The highest concentration observed was 17.20 g/m3 at Charlotte.
Ammonium samples in 2008 are summarized in Table 8.6 and 8.7. The highest concentration observed was 3.73 g/m3 at Hickory.
Organic Carbon samples in 2008 are summarized in Table 8.8 and 8.9. The highest concentration observed was 15.00 g/m3 at Hickory.
Elemental Carbon samples in 2008 are summarized in Table 8.10 and 8.11. The highest concentration observed was 2.67 g/m3 at Hickory.
Crustal Component samples in 2008 are summarized in Table 8.12 and 8.13. The highest concentration observed was 4.24 g/m3 at Charlotte.
Elemental lead samples for 2008 are summarized in Table 8.14 and 8.15. Out of 869 samples statewide, five samples exceeded 0.01 g/m3 ; 864 of these sample concentrations (99 percent) were less than 0.01 μg/m3. Two samples were greater than 0.014 g/m3. The highest concentration observed was 0.033 g/m3 at Hickory .
Figure 8.1 Location of Nitrate, Sulfate, Ammonium, Organic Carbon, Elemental Carbon, Crustal component, “Other” component, Monitoring Sites 2008 63
Table 8.1 Fine Particle Speciation Sites Operated in North Carolina in 2008
SITE NUMBER
ADDRESS
METHOD
COUNTY
37-021-0034
175 BINGHAM ROAD
SASS
BUNCOMBE
ASHEVILLE
37-035-0004
1650 1ST STREET
SASS
CATAWBA
HICKORY
37-057-0002
S.SALISBURY ST
SASS
DAVIDSON
LEXINGTON
37-067-0022
1300 BLK HATTIE AVE
SASS
FORSYTH
WINSTON-SALEM
37-107-0004
HIGHWAY 70 EAST AND HIGHWAY 58 SOUTH
SASS
LENOIR
KINSTON
37-119-0041
1130 EASTWAY DRIVE
SASS
MECKLENBURG
CHARLOTTE
37-159-0021
301 WEST ST & GOLD HILL AVE
SASS
ROWAN
ROCKWELL
37-183-0014
3801 SPRING FOREST RD
SASS
WAKE
RALEIGH
SITES OPERATED IN
8
2008
Table 8.2 Mean and Maximum Nitrate PM2.5 Concentration for 2008
SITE NUMBER
ADDRESS
NUM OBS
24-HOUR MAXIMA
ARITH MEAN
COUNTY
1st
2nd
3rd
4th
37-021-0034
175 BINGHAM ROAD
57
2.23
2.22
2.21
2.17
.25
BUNCOMBE
ASHEVILLE
37-035-0004
1650 1ST STREET
55
5.00
4.51
4.29
3.48
1.12
CATAWBA
HICKORY
37-057-0002
S.SALISBURY ST
60
3.47
3.40
3.19
2.79
.92
DAVIDSON
LEXINGTON
37-067-0022
1300 BLK HATTIE AVE
61
4.93
3.75
3.72
3.64
.98
FORSYTH
WINSTON-SALEM
37-107-0004
LENOIR
HIGHWAY 70 EAST AND HIGHWAY 58 SOUTH
10
5.32
2.82
2.58
.71
1.49
KINSTON
37-119-0041
1130 EASTWAY DRIVE
117
5.27
4.83
3.87
3.84
.93
MECKLENBURG
CHARLOTTE
64
SITE NUMBER
ADDRESS
NUM OBS
24-HOUR MAXIMA
ARITH MEAN
COUNTY
1st
2nd
3rd
4th
37-159-0021
ROWAN
301 WEST ST & GOLD HILL AVE
60
3.57
3.24
3.18
3.01
.87
ROCKWELL
37-183-0014
3801 SPRING FOREST RD
120
3.24
3.21
3.13
2.78
.78
WAKE
RALEIGH
Total Samples
540
Total Sites Sampled
8
Table 8.3 Nitrate PM2.5 - Quartile statistics for 2008
SITE NUMBER
ADDRESS
NUM OBS
QUARTILES
Mg/m2
MAXI
NUM
COUNTY
1st
2nd
3rd
37-021-0034
175 BINGHAM ROAD
57
.88
.45
.31
2.23
BUNCOMBE
ASHEVILLE
37-035-0004
1650 1ST STREET
55
1.46
.57
.34
5.00
CATAWBA
HICKORY
37-057-0002
S.SALISBURY ST
60
1.16
.58
.39
3.47
DAVIDSON
LEXINGTON
37-067-0022
FORSYTH
1300 BLK HATTIE AVE
61
1.16
.53
.32
4.93
WINSTON-SALEM
37-107-0004
LENOIR
HIGHWAY 70 EAST AND HIGHWAY 58 SOUTH
10
2.11
.71
.61
5.32
KINSTON
37-119-0041
MECKLENBURG
1130 EASTWAY DRIVE
117
1.04
.59
.33
5.27
CHARLOTTE
37-159-0021
ROWAN
301 WEST ST & GOLD HILL AVE
60
.96
.53
.36
3.57
ROCKWELL
37-183-0014
WAKE
3801 SPRING FOREST RD
120
.88
.53
.35
3.24
RALEIGH
Effective Sample Count
540
Total Sites Sampled
8
 Not including collocated samples.
65
Table 8.4 Mean and Maximum Sulfate PM2.5 Concentration for 2008
SITE NUMBER
ADDRESS
NUM OBS
24-HOUR MAXIMA
ARITH MEAN
COUNTY
1st
2nd
3rd
4th
37-021-0034
175 BINGHAM ROAD
57
9.40
6.90
6.44
6.11
2.69
BUNCOMBE
ASHEVILLE
37-035-0004
1650 1ST STREET
55
12.20
9.13
9.07
7.35
3.76
CATAWBA
HICKORY
37-057-0002
S.SALISBURY ST
60
10.90
9.46
8.05
7.75
3.85
DAVIDSON
LEXINGTON
37-067-0022
1300 BLK HATTIE AVE
61
11.10
11.00
8.32
8.08
3.80
FORSYTH
WINSTON-SALEM
37-107-0004
LENOIR
HIGHWAY 70 EAST AND HIGHWAY 58 SOUTH
10
8.39
5.41
4.73
2.70
2.96
KINSTON
37-119-0041
1130 EASTWAY DRIVE
117
17.20
10.40
8.78
8.51
3.70
MECKLENBURG
CHARLOTTE
37-159-0021
ROWAN
301 WEST ST & GOLD HILL AVE
60
10.10
9.69
9.03
8.05
3.81
ROCKWELL
37-183-0014
3801 SPRING FOREST RD
120
9.28
7.52
7.42
6.91
3.26
WAKE
RALEIGH
Total Samples
540
Total Sites Sampled
8
Table 8.5 Sulfate PM2.5 - Quartile statistics for 2008
SITE NUMBER
ADDRESS
NUM OBS
QUARTILES
MAXI
NUM
COUNTY
1st
2nd
3rd
37-021-0034
175 BINGHA