2011 Ambient Air Quality Report
STATE OF NORTH CAROLINA
Pat McCrory, Governor
DEPARTMENT OF
ENVIRONMENT
AND
NATURAL RESOURCES
John E. Skvarla, III, Secretary
DIVISION OF AIR QUALITY
Sheila C. Holman, Director
AMBIENT MONITORING SECTION
Donald D. Redmond, Jr., Chief
PUBLISHED
September 2013
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2011 Ambient Air Quality Report
Ambient Monitoring Section Report # 2013.01
Acknowledgements:
Primary Author: Wayne Cornelius
Additional Assistance: Lucyna Kozek
Vitaly Karpusenko
John Holland
Public Data Repositories:
US Environmental Protection Agency Air Quality System. 2010. National Air Data Group, Office of Air Quality Planning and Standards, US EPA OAQPS/OID/NADG AQS MD-C339-01 Research Triangle Park, NC 27711 http://www.epa.gov/ttn/airs/airsaqs/
National Atmospheric Deposition Program (NRSP-3). 2010. NADP Program Office, Illinois State Water Survey, 2204 Griffith Dr., Champaign, IL 61820 http://nadp.sws.uiuc.edu/
Published: September 2013
Not copyrighted.
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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 2011 to measure the outdoor concentrations of air pollutants. 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 2011.
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 2011.
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 2011 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:
Division of Air Quality
1641 Mail Service Center
Raleigh, North Carolina 27699-1641
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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
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Executive Summary
In 2011, the North Carolina Division of Air Quality (DAQ), the three local program agencies and one tribal agency (listed in Appendix A) collected 109,175 ambient 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 2011. 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 2011.
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 2011 in this report. This report presents a map and summary tables of five important volatile organic compounds for 2011.
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.
Two different types of particulate matter are routinely sampled in North Carolina. 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.
PM10 was sampled at 12 sites, yielding 1,275 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).
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PM2.5 was sampled at 35 sites yielding 4,574 daily samples. There were no exceedances of the ambient air quality standards for PM2.5 (35 g/m3 for 24-hour samples). 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 four sites, yielding 27,460 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 2.6 ppm was observed at 1401 Corporation Pky in Winston-Salem. The highest eight-hour concentration of 2.3 ppm was observed at 1401 Corporation Pky in Winston-Salem. The mean one-hour average has been decreasing by about 4 percent per year and the mean eight-hour average has been decreasing by about 18 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 have helped reduce the measured ambient concentrations of CO 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 45 sites, yielding 9,275 valid hourly averages. The National Ambient Air Quality Standard for O3 in 2011 was 0.075 ppm for the maximum 8-hour average.
In 2011, the 8-hour standard was exceeded 100 times, on 26 different days, with two counties having 9 exceedances at individual sites.
Sulfur dioxide (SO2) is mainly produced by combustion of fossil fuels containing sulfur compounds and the manufacture of sulfuric acid.
SO2 was sampled at eight sites, yielding 49,752 valid hourly averages. There were no exceedances of the 1971 National Ambient Air Quality Standards (140 ppb for a 24-hour average, 500 ppb for a three-hour average, 30 ppb for the annual arithmetic mean) at any network monitoring sites. However, there was one exceedance of the 2011 National Ambient Air Quality Standards (75 ppb for an 1-hour daily maximum concentration) at one network monitoring site: Highway 421 North, Wilmington in New Hanover County.
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.
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The criteria pollutant NO2 was sampled at two sites, yielding 16,464 valid hourly averages. There were no exceedances of the National Ambient Air Quality Standard (0.053 ppm for the annual arithmetic mean).
There were no exceedances of the 2010 National Ambient Air Quality Standards (100 ppb for the 1 hour average). The mean 1-hour average concentration has been stable for the past two years.
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 2011 using a Federal Reference Method. There have been no recent exceedances of the ambient air quality standard for lead (0.15 g/m3 for a rolling three month 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 2011 ranged from 4.95 (Scotland County) to 5.35 (Sampson County).
Speciated particulate samples were collected at four 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 and crustal material, there were 3,680 quantifiable concentrations in 2011.
By category, the highest concentrations of speciated particulate samples in 2011 were: organic carbon 23.60 μg/m3; sulfate 9.11 μg/m3; nitrate 5.68 μg/m3; ammonium 3.36 μg/m3 ; crustal component 2.43 μg/m3 and elemental carbon 1.39 μg/m3.
Although there was no sampling for lead using a criteria pollutant method, the speciated particulate monitoring network provided 832 samples of PM2.5 lead in 2011; 829 of these sample concentrations (99.6 percent) were less than the detection limit of the method. The largest sample exceeded 0.014 μg/m3.
Urban Air Toxics sampling in 2011 occurred at six sites, five 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 benzene concentrations were 0.13 to 0.28 ppb at the urban sites and 0.33 ppb at the rural site. Median toluene concentrations were 0.18 to 0.46 ppb at the urban sites and 0.09 ppb at the rural site. Median ethylbenzene concentrations were 0.05 to .09 ppb at the urban sites and less than 0.03 ppb at the rural site. Median m/p-xylene concentrations were 0.12 to 0.16 ppb at viii
the urban sites and less than 0.04 ppb at the rural site. Median o-xylene concentrations were 0.05 to 0.011 ppb at the urban sites and less than 0.02 at the rural site. Median 1, 3-butadiene concentrations were 0.00 to 0.05 ppb at the urban sites and less than 0.001 at the rural site. Ambient monitoring data for hazardous and/or toxic air pollutants are available on the web at http://daq.state.nc.us/toxics/uat/uat_data.shtml.
Ambient Trends: Annual average statewide concentrations of criteria pollutants changed in 2011 as follows:
 PM10 decreased by 48 percent since 1991.
 PM2.5 decreased by 40 percent since 1999.
 CO (as 8-hour overlapping averages) decreased by 62 percent since 1998.
 Ozone (as daily maximum 8-hour concentrations) decreased by 11 percent since 1991.
 Nitrogen dioxide concentrations (monitored only in Forsyth and Mecklenburg counties) have remained nearly constant since 1991.
Acid Rain Trends: From 1991 to 2011:
 The annual average pH in rain increased about 11 percent.
 Annual average ammonium concentrations increased about 52 percent; 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 32 percent.
 Annual average sulfate concentrations in rain decreased about 51 percent.
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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................................................................................................................................ 3
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 .................................................................................................................................. 5
3 Standards ................................................................................................................................... 7
4 Ambient Air Quality Monitoring Program ................................................................................. 9
5 Pollutant Monitoring Results .................................................................................................... 16
5.1 PM10 ...................................................................................................................................... 17
5.2 Fine Particulate Matter, (PM2.5) ............................................................................................ 20
5.3 Carbon Monoxide .................................................................................................................. 25
5.4 Ozone .................................................................................................................................... 28
5.5 Sulfur Dioxide ........................................................................................................................ 32
5.7 Nitrogen Dioxide ................................................................................................................... 36
5.8 Lead ...................................................................................................................................... 37
5.8.1 Special Studies .................................................................................................................... 37
5.8.2 Future Lead Monitoring ...................................................................................................... 37
6 Air Quality Index ..................................................................................................................... 38
7 Acid Rain ................................................................................................................................ 52
7.1 Sources ................................................................................................................................. 52
7.2 Effects .................................................................................................................................. 52
7.3 Monitoring ............................................................................................................................. 52
8. Fine Particle Speciation .......................................................................................................... 56
8.1 Description of pollutants ....................................................................................................... 56 x
8.1.1 Nitrate ................................................................................................................................ 56
8.1.2 Sulfate ................................................................................................................................ 56
8.1.3 Ammonium ......................................................................................................................... 56
8.1.4 Organic Carbon ................................................................................................................... 56
8.1.5 Elemental Carbon................................................................................................................ 56
8.1.6 Crustal Component (Fine Dust) .......................................................................................... 57
8.1.7 “Other” Speciated components. .......................................................................................... 57
8.2 Sources ................................................................................................................................. 57
8.3 Effects .................................................................................................................................. 58
8.4 Monitoring ............................................................................................................................ 58
9. Urban Air Toxics .................................................................................................................... 71
9.1 Sources ................................................................................................................................. 71
9.2 Effects .................................................................................................................................. 71
9.3 Benzene ................................................................................................................................ 71
9.3.1 Sources ............................................................................................................................... 72
9.3.2 Effects ............................................................................................................................... 72
9.4 Toluene ................................................................................................................................ 72
9.4.1 Sources ............................................................................................................................... 72
9.4.2 Effects ................................................................................................................................ 73
9.5 Ethylbenzene .......................................................................................................................... 73
9.5.1 Sources ............................................................................................................................... 73
9.5.2 Effects ................................................................................................................................ 73
9.6 Xylene ................................................................................................................................... 73
9.6.1 Sources ............................................................................................................................... 73
9.6.2 Effects ................................................................................................................................ 73
9.7 1,3-Butadiene ........................................................................................................................ 74
9.7.1 Sources ............................................................................................................................... 74
9.7.2 Effects ................................................................................................................................ 74
9.8 Monitoring in 2011 ............................................................................................................... 74
10 Statewide Trends ..................................................................................................................... 81
10.1 Particulate Matter ................................................................................................................. 81
10.3 Ozone .................................................................................................................................. 81
10.4 Sulfur Dioxide ...................................................................................................................... 81
10.5 Nitrogen Dioxide ................................................................................................................. 82
10.6 pH ........................................................................................................................................ 82
10.7 Ammonium Ion .................................................................................................................... 82
10.8 Nitrate Ion ............................................................................................................................ 82
10.9 Sulfate Ion ............................................................................................................................ 82
Appendix A. Air Pollution Monitoring Agencies ......................................................................... 90
Appendix B. Exceptional Events .................................................................................................. 93
Appendix C. Box-And-Whisker Plots .......................................................................................... 94
Appendix D. Nonattainment and North Carolina ......................................................................... 95
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List of Tables
Table 3.1 National and North Carolina Ambient Air Quality Standards in 2011........................... 8
Table 4.1 Ambient Air Monitoring Sites Operated in North Carolina, 2011 ............................... 11
Table 5.1 PM10 in Micrograms Per Cubic Meter for 2011 ........................................................... 18
Table 5.2 PM2.5 in Micrograms Per Cubic Meter for 2011........................................................... 21
Table 5.3 Carbon Monoxide in Parts Per Million for 2011 .......................................................... 26
Table 5.4 Eight-Hour Ozone in Parts Per Million for 2011 .......................................................... 29
Table 5.5 Sulfur Dioxide in Parts Per Million from All Sites for 2009-2011 .............................. 33
Table 5.6 Nitrogen Dioxide in Parts Per Million for 2011 ........................................................... 36
Table 6.1 Air Quality Index Category Days in the Major Metropolitan Statistical Areas, 2011 . 41
Table 7.1 pH, Conductivity in Microsiemans per Centimeter and Precipitation in Inches from the National Atmospheric Deposition Program for 2011 ........................................................... 54
Table 7.2 Ion Concentrations in Milligrams per Liter (Precipitation-weighted Annual Means) from the National Atmospheric Deposition Program Data for 2011 .................................... 55
Table 8.1 Fine Particles Speciation Sites Operated in North Carolina in 2011 ............................ 60
Table 8.2 Mean and Maximum Nitrate PM2.5 Concentration for 2011 ........................................ 61
Table 8.3 Nitrate PM2.5-Quartile statistics-Micrograms/Cubic Meter (LC) for 2011 .................. 61
Table 8.4 Mean and Maximum Sulfate PM2.5 Concentration for 2011 ........................................ 62
Table 8.5 Sulfate PM2.5- Quartile statistics- Micrograms/Cubic Meter (LC) for 2011 ................ 63
Table 8.6 Mean and Maximum Ammonium PM2.5 Concentration for 2011 ................................ 63
Table 8.7 Ammonium Ion PM2.5- Quartile statistics- Micrograms/Cubic Meter (LC) for 2011 .. 64
Table 8.8 Mean and Maximum Organic Carbon PM2.5 Concentration for 2011 .......................... 65
Table 8.9 Organic Carbon CSN PM2.5- Quartile statistics- Micrograms/Cubic Meter (LC) for
2011...................................................................................................................................... 65
Table 8.10 Mean and Maximum Elemental Carbon PM2.5 Concentration for 2011 .................... 66
Table 8.11 Elemental Carbon CSN PM2.5- Quartile statistics- Micrograms/Cubic Meter (LC) for
2011...................................................................................................................................... 67
Table 8.12 Mean and Maximum Crustal Component PM2.5 Concentration for 2011 .................. 68
Table 8.13 Crustal Component PM2.5- Quartile statistics- Micrograms/Cubic Meter (LC) for
2011....................................................................................................................................... 68
Table 8.14 Mean and Maximum Lead PM2.5 Concentration for 2011 .......................................... 69
Table 8.15 Lead PM2.5- Quartile statistics- Micrograms/Cubic Meter (LC) for 2011.................. 70
Table 9.1 Benzene - Parts per billion for 2011 ............................................................................. 76
Table 9.2 Toluene - Parts per billion for 2011 .............................................................................. 77
Table 9.3 Ethylbenzene - Parts per billion for 2011 ..................................................................... 78
Table 9.4 m/p-Xylene - Parts per billion for 2011 ........................................................................ 78
Table 9.5 o-Xylene -Parts per billion for 2011 ............................................................................. 79
Table 9.6 1,3-Butadiene ................................................................................................................ 80
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List of Figures
Figure 4.1 Monitoring Sites Active in 2011 ................................................................................. 10
Figure 5.1 Location of PM10 Monitoring Sites ............................................................................. 17
Figure 5.2 PM10: Second Highest 24-Hour Averages, 2011 ........................................................ 19
Figure 5.3 PM10: Maximum Annual Arithmetic Means, 2011 .................................................... 19
Figure 5.4 Location of PM2.5 Monitoring Sites ............................................................................ 20
Figure 5.5 PM2.5: 98th percentile, 2011 ........................................................................................ 23
Figure 5.6 PM2.5: Annual Arithmetic Means, 2011 ..................................................................... 24
Figure 5.7 PM2.5: Design Values by County, 2007-2011 ............................................................ 24
Figure 5.8 Location of Carbon Monoxide Monitoring Sites ........................................................ 26
Figure 5.9 Carbon Monoxide: Second Highest 1-Hour Concentration, 2011 .............................. 27
Figure 5.10 Carbon Monoxide: Second Highest Non-overlapping 8-Hour Concentration, 2011 27
Figure 5.11 Location of Ozone Monitoring Sites ......................................................................... 28
Figure 5.12 Ozone: Mean Annual Fourth Highest 8-Hour Average, 2009-2011 ........................ 31
Figure 5.13 Locations of Sulfur Dioxide Monitoring Sites in 2009, 2010 and 2011 ................... 32
Figure 5.14 Sulfur Dioxide Design Values by County, 2009-2011 ............................................. 33
Figure 5.15 Sulfur Dioxide: Second Highest 3-Hour Averages in the Most recent Year of Data
from 2009, 2010 and 2011 .................................................................................................... 35
Figure 5.16 Sulfur Dioxide: Second Highest 24-Hour Averages in the Most Recent Year of Data from 2009, 2010 or 2011 ...................................................................................................... 35
Figure 5.17 Location of Nitrogen Dioxide Monitoring Sites ...................................................... 36
Figure 6.1 Daily Air Quality Index Values for Asheville, 2011 .................................................. 42
Figure 6.2 Daily Air Quality Index Summary for Asheville, 2011 .............................................. 42
Figure 6.3 Daily Air Quality Index Values for Charlotte-Gastonia, 2011 .................................... 43
Figure 6.4 Daily Air Quality Index Summary for Charlotte-Gastonia, 2011 ............................... 43
Figure 6.5 Daily Air Quality Index Values for Fayetteville, 2011 ............................................... 44
Figure 6.6 Daily Air Quality Index Summary for Fayetteville, 2011 ........................................... 44
Figure 6.7 Daily Air Quality Index Values for Goldsboro, 2011 ................................................. 45
Figure 6.8 Daily Air Quality Index Summary for Goldsboro, 2011 ............................................. 45
Figure 6.9 Daily Air Quality Index Values Greensboro-Winston-Salem-High Point, 2011 ........ 46
Figure 6.10 Daily Air Quality Index Summary Greensboro-Winston-Salem-High Point, 2011 .. 46
Figure 6.11 Daily Air Quality Index Values for Greenville, 2011 ............................................... 47
Figure 6.12 Daily Air Quality Index Summary for Greenville, 2011 ........................................... 47
Figure 6.13 Daily Air Quality Index Values for Hickory-Morganton-Lenoir, 2011 .................... 48
Figure 6.14 Daily Air Quality Index Summary for Hickory-Morganton-Lenoir, 2011 ............... 48
Figure 6.15 Daily Air Quality Index Values for Raleigh-Durham- Chapel Hill, 2011 ................ 49
Figure 6.16 Daily Air Quality Index Summary for Raleigh-Durham-Chapel Hill, 2011 ............. 49
Figure 6.17 Daily Air Quality Index Values for Rocky Mount, 2011 .......................................... 50
Figure 6.18 Daily Air Quality Index Summary for Rocky Mount, 2011 ..................................... 50
Figure 6.19 Daily Air Quality Index Values for Wilmington, 2011 ............................................. 51
Figure 6.20 Daily Air Quality Index Summary for Wilmington, 2011 ........................................ 51 xiii
Figure 7.1 Annual Mean pH Values at North Carolina NADP Sites, 2011.................................. 53
Figure 8.1 Location of Nitrate, Sulfate, Ammonium, Organic Carbon, Elemental Carbon, Crustal
component, "Other" component, Monitoring Sites 2011 ...................................................... 60
Figure 9.1 Location Urban Air Toxics Monitoring Sites 2011 ..................................................... 76
Figure 10.1 Distribution of Statewide Second-Maximum 24-Hour PM10 Concentrations, 1989-
2011, and Smoothed Regression Trend Lines ..................................................................... 83
Figure 10.2 Distribution of Statewide Weighted Annual Mean PM2.5 Concentrations, 1999- 2010, and Smoothed Regression Trend Line. ......................................................................................... 83
Figure 10.3 Distribution of Statewide 98th Percentile PM2.5 Concentrations, 1999- 2010, and Smoothed Regression Trend Line. ................................................................................................ 84
Figure 10.4 Distribution of Statewide Second-Maximum 8-Hour Carbon Monoxide
Concentrations, 1997-2011, and Smoothed Regression Trend Line ................................... 84
Figure 10.5 Distribution of Statewide Fourth-Maximum 8-Hour Ozone Concentrations, 1990-
2011, and Smoothed Regression Trend Line ....................................................................... 85
Figure 10.6 Number of Days with Exceedances of 8-Hour Ozone Averages of 0.075 ppm or
Greater, 1990-2011 ............................................................................................................ 85
Figure 10.7 Distribution of Statewide Second- Maximum 24-Hour Sulfur Dioxide
Concentrations, 1989- 2011, and Smoothed Regression Trend Line ................................. 86
Figure 10.8 Distributions of Forsyth and Mecklenburg County Annual Mean Nitrogen Dioxide
Concentrations, 1989- 2011, and Smoothed Regression Trend Line .................................. 86
Figure 10.9 Distribution of Statewide Annual Mean pH, 1991- 2011.......................................... 87
Figure 10.10 Distribution of Statewide Annual Mean Ammonium Ion Concentrations,
1991- 2011 .......................................................................................................................... 87
Figure 10.11 Distribution of Statewide Annual Mean Nitrate Ion Concentrations, 1991- 2011,
and Smoothed Regression Trend Line ................................................................................. 88
Figure 10.12 Distribution of Statewide Annual Mean Sulfate Ion Concentrations, 1991- 2011,
and Smoothed Regression Trend Line .................................................................................. 88
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1
1. Introduction
This annual report summarizes the ambient air monitoring performed in calendar year 2011 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 109,175 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 for 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. 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 six 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 2011.
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 2011, two sizes of particulate matter were monitored, PM10 and PM2.5. PM10 is particulate matter with an aerodynamic diameter less than or equal to 10 m. PM10 has been sampled in North Carolina since 1985. Monitoring PM2.5 (aerodynamic diameter less than or equal to 2.5 m) became a separate requirement in 1999, and sampling has been performed in N.C. since that year.
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 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 3
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 has little or no impact on 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 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.
4
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 high short-term concentrations. 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 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.
5
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 average concentration of lead in leaded gasoline has decreased, and the availability of leaded automotive fuel has declined, virtually eliminating automotive gasoline as a source of atmospheric lead. 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 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 6
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 2011 are summarized in Table 3.1.
8
Table 3.1 National and North Carolina Ambient Air Quality Standards in 2011
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
PM-2.5
24 hour average
(40CFR50, App. N)
1 year
average1 quarterly- weighted arithmetic
mean
12 μg/m3(2)
12 μg/m3(2)
12 μg/m3(2)
1 year
average1 quarterly- weighted arithmetic
mean
15 μg/m3(3)
15 μg/m3(3)
15 μg/m3(3)
1 day
average1 98th percentile
35 μg/m3(4)
35 μg/m3(4)
35 μg/m3(4)
PM-10
24 hour average
(40CFR50, App. N)
1 day
average1 2nd maximum5
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)
8 hours
Average6 arithmetic mean 4th maximum
0.075 ppm (7) (157 μg/m3)
0.075 ppm (7) (157 μg/m3)
0.075 ppm (7) (157 μg/m3)
SO2
1 hour average
3 hours (non-overlapping)
2nd maximum
500 ppb (1,300 μg/m3)
0.50 ppm (1,300 μg/m3)
1 year
99th percentile of
Daily Maximum
75 ppb(8)
75 ppb(8)
NO2
1 hour average
1 year
1 year
arithmetic mean
98th percentile of
Daily Maximum
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(9)
0.15 μg/m3(9)
0.15 g/m3(9)
1. Arithmetic mean over the 3 most current years.
2. Effective December 14, 2012.
3. 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.
4. 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).
5. In July 1997, a percentile-based statistic replaced the 2nd maximum, but in May 1999 the 2nd maximum standard was reinstated.
6. Arithmetic mean value over the most recent 3 consecutive, complete calendar years.
7. Effective May 27, 2008
8. To attain this standard, the 3-year average of the 99th percentile of 1-hour daily maximum concentrations must not exceed 75 ppb (effective June 2, 2010).
9. 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 2011. 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 2011 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
sampling sites once every six days to replace sample media and check the operation and10
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.
Shaded counties have monitors.
Monitor Location: ◊ O3 □ PM2.5 ○ CO Δ SO2 ⌂ NO2 * PM10
Figure 4.1 Monitoring Sites Active in 201111
Table 4.1 Ambient Air Monitoring Sites Operated in North Carolina, 2011
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
37-011-9991
PISGAH NATIONAL FOREST
O3
AVERY
NEWLAND
37-013-0007
1945 SANDY FORKS RD
SO2
BEAUFORT
AURORA
37-013-0151
229 NC HWY 306 N
SO2
BEAUFORT
BATH
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
37-031-9991
OPEH GROUNDS FARM
O3
CARTERET
BEAUFORT
37-033-0001
7074 CHERRY GROVE RD
O3
PM2.5
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
37-051-0008
7112 COVINGTON LANE
O3
CUMBERLAND
WADE
37-051-0009
4533 RAEFORD RD
PM10
PM2.5
CUMBERLAND
FAYETTEVILLE
12
SITE
ADDRESS
POLLUTANTS
COUNTY
37-051-1003
3625 GOLFVIEW RD
O3
SO2
CUMBERLAND
HOPE MILLS
37-057-0002
SOUTH SALISBURY STREET
PM2.5
DAVIDSON
LEXINGTON
37-059-0003
220 CHERRY STREET
O3
DAVIE
MOCKSVILLE
37-061-0002
HIGHWAY 50
PM2.5
DUPLIN
KENANSVILLE
37-063-0015
801 STADIUM DRIVE
O3
PM2.5
PM10
DURHAM
DURHAM
37-065-0004
900 SPRINGFIELD RD
PM2.5
EDGECOMBE
ROCKY MOUNT
37-065-0099
7589 NC HIGHWAY 33 NW
O3
EDGECOMBE
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
13
SITE
ADDRESS
POLLUTANTS
COUNTY
37-077-0001
WATER TREATMENT PLANT JOHN
O3
GRANVILLE
UMSTEAD HOSP
BUTNER
37-081-0013
205 WILOUGHBY BLVD
PM2.5
PM10
O3
GUILFORD
GREENSBORO
37-081-0014
2127 SANDY RIDGE ROAD
PM2.5
GUILFORD
COLFAX
37-087-0008
2236 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
37-099-0005
BARTNET KNOB FIRETOWER ROAD
O3
JACKSON
CHEROKEE
37-099-0006
US ROUTE 19 NORTH
PM2.5
JACKSON
CHEROKEE RESERVATION
37-101-0002
1338 JACK ROAD
O3
PM2.5
JOHNSTON
CLAYTON
37-107-0004
CORNER HIGHWAY 70 EAST
O3
PM2.5
LENOIR
KINSTON
37-109-0004
1487 RIVERVIEW ROAD
O3
LINCOLN
LINCOLNTON
37-111-0004
676 STATE STREET
PM2.5
PM10
MCDOWELL
MARION
37-113-9991
USDA SOUTHERN RESEARCH STATION
O3
MONTGOMERY
COWEETA
37-117-0001
1210 HAYES STREET
O3
PM2.5
MARTIN
JAMESVILLE
14
SITE
ADDRESS
POLLUTANTS
COUNTY
37-119-0003
FIRE STATION # 11, 620 WEST 28TH STREET
PM10
MECKLENBURG
CHARLOTTE
37-119-0041
1130 EASTWAY DRIVE
CO
SO2
PM2.5
NO2
O3
MECKLENBURG
CHARLOTTE
PM10
37-119-0042
1935 EMERYWOOD DRIVE
PM2.5
PM10
MECKLENBURG
CHARLOTTE
37-119-0043
513 RADIO ROAD
PM2.5
MECKLENBURG
CHARLOTTE
37-119-1005
400 WESTINGHOUSE BLVD.
O3
MECKLENBURG
CHARLOTTE
37-119-1009
HWY 29 NORTH AT HUDSPETH RD
O3
MECKLENBURG
CHARLOTTE
37-121-0001
CITY HALL, SUMMIT STREET
PM2.5
MITCHELL
SPRUCE PINE
37-123-0001
112 PERRY DRIVE
PM2.5
PM10
MONTGOMERY
CANDOR
37-123-9991
136 PERRY DR
O3
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
37-145-0003
STATE HIGHWAY 49 SOUTH
O3
PERSON
ROXBORO
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
SO2
ROCKINGHAM
BETHANY
37-159-0021
301 WEST ST & GOLD HILL AVENUE
O3
PM2.5
ROWAN
ROCKWELL
15
SITE
ADDRESS
POLLUTANTS
COUNTY
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 NORTH
RALEIGH
37-183-0020
E. MILLBROOK MIDDLE SCHOOL
PM2.5
WAKE
3720 LAKE WHEELER RD
RALEIGH
37-189-0003
361 JEFFERSON ROAD
PM2.5
WATAUGA
BOONE
37-191-0005
DILLARD MIDDLE SHOOL,
PM2.5
WAYNE
DEVEREAU STREET
GOLDSBORO
37-199-0004
4666 STATE HIGHWAY 128
O3
YANCEY
BURNSVILLE
Sites operated in 2011
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 that have been reviewed and approved by EPA 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 2011 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. Two of the 108 monitors used for this report operated most recently in 2010 or 2009.
17
5.1 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 2011, 1,275 ordinary 24-hour samples of PM10 were collected from monitors located at 12 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 5.1.
There were no exceedances of the PM10 ambient air quality standards in 2011. The highest 24-hour maximum concentration was 43 g/m3, or about 29 percent of the standard (150 g/m3). The highest annual arithmetic mean was 19.4 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
18
Table 5.1 PM10 in Micrograms Per Cubic Meter for 2011
SITE NUMBER
ADDRESS
NUM
OBS
24-HOUR MAXIMA
ARITH
MEAN
COUNTY
1st
2nd
3rd
4th
37-035-0004
1650 1ST. ST.
59
26
25
25
25
13.6
CATAWBA
HICKORY
37-051-0009
CUMBERLAND
4533 RAEFORD ROAD
FAYETTEVILLE
61
37
30
27
25
13.3
37-063-015
801 STADIUM DRIVE
110
33
32
27
26
14.4
DURHAM
DURHAM
37-067-0022
1300 BLK. HATTIE AVE
288
33
30
30
30
14.8
FORSYTH
WINSTON-SALEM
37-067-0023
FORSYTH
1401 CORPORATION PARKWAY
186
34
33
31
31
15.6
WINSTON-SALEM
37-081-0013
205 WILOUGHBY BLVD
57
25
20
19
18
10.1
GUILFORD
GREENSBORO
37-111-0004
MCDOWELL
676 STATE STREET
MARION
49
26
25
23
23
12.8
37-119-0003
MECKLENBURG
FIRE STA #11 620 MORETZ STREET
58
43
43
43
32
19.4
CHARLOTTE
37-119-0041
1130 EASTWAY DRIVE
118
37
35
34
33
15.9
MECKLENBURG
CHARLOTTE
37-119-0042
1935 EMERYWOOD DRIVE
119
43
34
33
33
16.7
MECKLENBURG
CHARLOTTE
37-123-0001
112 PERRY DRIVE
52
27
25
25
17
11.5
MONTGOMERY
CANDOR
37-183-0014
3801 SPRING FOREST RD.
118
32
26
25
24
13.9
WAKE
RALEIGH
Total Samples
1,275
Total Sites Sampled
12
19
Figure 5.2 PM10: Second Highest 24-Hour Averages, 2011
Figure 5.3 PM10: Maximum Annual Arithmetic Means, 2011 20
5.2 Fine Particulate Matter, (PM2.5)
In 2011, 35 sites were used to monitor PM2.5 and 4,574 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 5.2.
There were no exceedances of the PM2.5 24-hour ambient air quality standards in 2011. The highest annual arithmetic mean was 11.00 g/m3, which is about 17 percent below the level of the standard (15 g/m3), at Charlotte in Mecklenburg County. (See Table 5.2).
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 2009 through 2011, using the federal reference method monitors. Thirty counties have enough reported data to compute this metric correctly, all of them appear to be attaining the ambient standard. Attainment decisions for PM2.5 will be based on the design values observed during 2009 through 2011.
Figure 5.4 Location of PM2.5 Monitoring Sites
21
Table 5.2 PM2.5 in Micrograms Per Cubic Meter for 2011
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
90
35.5
20.7
20.5
17.8
20.7
9.52
BURLINGTON
37-021-0034
BUNCOMBE
175 BINGHAM ROAD
ASHEVILLE
119
20.0
18.8
18.5
18.2
18.5
9.18
37-033-0001
CASWELL
7074 CHERRY GROVE RECREATION
61
18.6
18.3
17.9
16.3
18.3
8.33
37-035-0004
1650 1ST. ST.
231
32.2
27.7
24.2
22.7
22.3
10.42
CATAWBA
HICKORY
37-037-0004
325 RUSSETT
117
25.4
24.1
19.5
18.6
19.5
8.37
CHATHAM
PITTSBORO
37-051-0009
CUMBERLAND
4533 RAEFORD ROAD
91
24.0
22.1
20.7
20.6
22.1
9.74
FAYETTEVILLE
37-057-0002
DAVIDSON
SOUTH SALISBURY STREET
119
21.5
20.4
20.2
20.1
20.2
10.72
LEXINGTON
37-061-0002
328LIMESTONE RD
119
40.0
21.3
21.0
20.5
21.0
9.13
DUPLIN
KENANSVILLE
37-063-0015
801 STADIUM DRIVE
115
21.3
20.0
18.6
18.0
18.6
9.19
DURHAM
DURHAM
37-065-0004
900 SPRINGFIELD
114
29.0
28.2
21.8
21.6
21.8
8.98
EDGECOMBE
ROCKY MOUNT
37-067-0022
FORSYTH
1300 BLOCK, HATTIE AVENUE
344
26.5
24.1
22.2
20.9
19.9
9.61
WINSTON-SALEM
37-067-0030
FORSYTH
FRATERNITY CHURCH ROAD
109
22.9
20.2
19.3
17.8
19.3
9.27
WINSTON-SALEM
37-071-0016
GASTON
1622 EAST GARRISON BLVD
85
28.7
26.4
23.3
22.3
26.4
10.54
GASTONIA
37-081-0013
GUILFORD
205 WILOUGHBY BLVD
87
26.0
21.1
19.3
17.3
21.1
8.87
GREENSBORO
37-081-0014
HAYWOOD
2127 SANDY RIDGE ROAD
116
23.5
20.0
20.0
17.8
20.0
9.18
WAYNESVILLE
22
SITE NUMBER
ADDRESS
NUM
OBS
24-HOUR MAXIMA
PERCENTILE
ARITH
MEAN
COUNTY
1st
2nd
3rd
4th
98TH
37-087-0012
HAYWOOD
550 VANCE STREET
WAYNESVILLE
117
27.3
27.0
22.8
21.7
22.8
9.98
37-099-0006
US RT 19 NORTH
99
22.1
21.8
20.3
18.7
21.8
9.61
JACKSON
CHEROKEE
37-101-0002
1338 JACK ROAD
106
35.8
28.0
20.2
19.8
20.2
9.18
JOHNSTON
CLAYTON
37-107-0004
LENOIR
CORNER HWY 70 EAST
119
71.7
41.5
27.5
26.3
27.5
9.96
KINSTON
37-111-0004
676 STATE STREET
116
24.1
22.7
21.0
18.9
21.0
9.85
MCDOWELL
MARION
37-117-0001
1210 HAYES ST
115
31.3
31.0
29.4
23.7
29.4
8.98
MARTIN
JAMESVILLE
37-119-0041
MECKLENBURG
1130 EASTWAY DRIVE
349
28.7
28.0
26.1
25.6
23.1
10.70
CHARLOTTE
37-119-0042
MECKLENBURG
1935 EMERYWOOD DRIVE
116
31.2
26.2
26.2
24.7
26.2
11.00
CHARLOTTE
37-119-0043
MECKLENBURG
513 RADIO ROAD
CHARLOTTE
353
28.3
27.0
26.0
22.9
21.4
10.15
37-121-0001
MITCHELL
CITY HALL SUMMIT ST
116
23.5
20.1
19.2
18.1
19.2
9.05
SPRUCE PINE
37-123-0001
112 PERRY DRIVE
118
30.3
22.6
20.8
20.2
20.8
9.17
MONTGOMERY
CANDOR
37-129-002
NEW HANOVER
6028 HOLLY SHELTER RD
119
35.9
34.2
33.1
25.0
33.1
8.58
CASTLE HAYNE
37-147-0006
PITT
403 GOVERNMENT
CIRCLE
121
28.7
27.7
24.0
22.4
24.0
8.14
37-155-0005
ROBESON
1170 LINKHAM ROAD
119
35.2
22.7
20.6
19.3
20.6
10.10
LUMBERTON
37-159-0021
ROWAN
301 WEST ST & GOLD HILL AVE
117
22.4
18.7
18.5
17.7
18.5
10.15
ROCKWELL
37-173-0002
SWAIN
CENTER ST/PARKS 7 REC
48
21.3
17.1
16.2
15.6
21.3
9.01
FACILITY
37-183-0014
WAKE
3801 SPRING FOREST RD
119
27.5
24.0
20.2
19.0
20.2
9.46
RALEIGH
23
SITE NUMBER
ADDRESS
NUM
OBS
24-HOUR MAXIMA
PERCENTILE
ARITH
MEAN
COUNTY
1st
2nd
3rd
4th
98TH
37-183-0020
WAKE
3720 LAKE WHEELER RD
115
27.7
25.0
22.8
20.4
22.8
9.56
37-189-0003
WATAUGA
361JEFFERSON HWY
116
21.6
21.1
20.0
19.8
20.0
8.08
BOONE
37-191-0005
WAYNE
DILLARD MIDDLE SCHOOL
59
28.6
22.3
21.7
16.3
22.3
9.39
GOLDSBORO
Total Samples
4,574
Total Sites Sampled
35
Figure 5.5 PM2.5: 98th Percentile, 2011
24
Figure 5.6 PM2.5: Annual Arithmetic Means, 2011
Figure 5.7 PM2.5 Design Values by County, 2009-2011
25
5.3 Carbon Monoxide
Carbon monoxide (CO) data were collected for two purposes in 2011: 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 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 2011, four sites were used to monitor CO and 27,460 valid hourly averages were collected. Data were collected from monitors in Charlotte, Winston-Salem and Raleigh (at 2 locations, one of which is operated only in winter 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 5.3.
There were no exceedances of the CO ambient air quality standards in 2011. The highest 1-hour average was 2.6 parts
per million (ppm), or about 7 percent of the standard (35 ppm). This value occurred at the 1401 Corporation Parkway site in Winston-Salem (Forsyth County). The highest 8-hour average was 2.3 ppm, at the 1401 Corporation Parkway site, which is about 26 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) is an intentional control strategy that helps assure cleaner-running cars. Other factors include increased news media interest and public awareness, and the 26
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.
Figure 5.8 Location of Carbon Monoxide Monitoring Sites
Table 5.3 Carbon Monoxide in Parts Per Million for 2011
SITE NUMBER
ADDRESS
NUM
OBS
ONE-HOUR
MAXIMA
EIGHT-HOUR
MAXIMA
COUNTY
1st
2nd
1st
2nd
37-067-0023
1401 CORPORATION PKY
8,536
2.6
2.6
2.3
2.1
FORSYTH
WINSTON-SALEM
37-119-0041
MECKLENBURG
1130 EASTWAY DRIVE
CHARLOTTE
8,624
2.3
2.0
1.8
1.5
37-183-0014
WAKE
3801 SPRING FOREST RD.
RALEIGH
8,255
1.8
1.8
1.4
1.4
37-183-0018
WAKE
US HWY 70 WEST AND NC HWY 50 NORTH
2,045
1.9
1.8
1.5
1.4
RALEIGH
Total Samples
27,460
Total Sites Sampled
4
27
Figure 5.9 Carbon Monoxide: Second Highest 1-Hour Concentration, 2011
Figure 5.10 Carbon Monoxide: Second Highest Non-overlapping 8-Hour
Concentration, 2011
28
5.4 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.
Federal, state, local and tribal program agencies operated 45 monitoring sites in 2011 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 8-hour data is given in Table 5.4. These 45 monitoring sites provided 9,275 site-days of valid data (a success rate of 96 percent for the days that sampling is required).
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 total of 100 times at the 45 sites that monitored for O3. Twenty- six monitors had at least one exceedance. The largest number at one monitor was 9
in Enochville (Rowan County) and in Charlotte in (Mecklenburg County). These exceedances were distributed over 26 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_2011.pdf or http://www.ncair.org/monitor/data/files/o3data_2011.pdf .
Historical average fourth-highest 8-hour concentrations of O3 in counties where monitors were operated in 2011 are shown in Figure 5.12. Monitors whose fourth-highest 8-hour ozone concentration (averaged over three years) exceeds 0.075 ppm are deemed in violation of the EPA 8-hour standard.
Figure 5.11 Location of Ozone Monitoring Sites 29
Table 5.4 Eight-Hour Ozone in Parts Per Million for 2011
SITE NUMBER
ADDRESS
VALID
DAYS
VALID DAILY 8-HR MAXIMUM
N0. VALUES
COUNTY
.>.075
1st
2nd
3rd
4th
MEAS
37-003-0004
106 WAGGIN’ TRAIL
206
.072
.071
.071
.067
0
ALEXANDER
TAYLORSVILLE
37-011-0002
7510 BLUE RIDGE
210
.065
.063
.063
.062
0
AVERY
LINVILLE
37-011-9991
PISGAH NATIONAL FOREST
196
.065
.065
.064
.062
0
AVERY
NEWLAND
37-021-0030
ROUTE 191 SOUTH BREVARD RD
208
.070
.067
.067
.067
0
BUNCOMBE
BENT CREEK
37-027-0003
HWY 321 NORTH
214
.070
.067
.067
.066
0
CALDWELL
LENOIR
37-031-9991
OPEN GROUNDS FARM
161
.066
.065
.065
.063
0
CARTERET
BEAUFORT
37-033-0001
7074 CHERRY GROVE RD
209
.079
.075
.074
.070
1
CASWELL
REIDSVILLE
37-037-0004
325 RUSSETT RUN
214
.070
.069
.067
.067
0
CHATHAM
PITTSBORO
37-051-0008
7112 COVINGTON LANE
213
.075
.074
.074
.073
0
CUMBERLAND
WADE
37-051-1003
3625 GOLFVIEW ROAD
213
.083
.081
.080
.076
4
CUMBERLAND
HOPE MILLS
37-059-0003
220 CHERRY STREET
214
.076
.074
.072
.072
1
DAVIE
MOCKSVILLE
37-063-0015
801 STADIUM DRIVE
208
.077
.074
.072
.070
1
DURHAM
DURHAM
37-065-0099
7589 NC HWY 33-NW
201
.077
.075
.074
.072
1
EDGECOMBE
LEGGETT
37-067-0022
1300 BLK. HATTIE AVENUE
214
.084
.081
.079
.076
5
FORSYTH
WINSTON-SALEM
37-067-0028
6496 BAUX MOUNTAIN RD
214
.071
.070
.069
.068
0
FORSYTH
WINSTON-SALEM
37-067-0030
FRATERNITY CHURCH ROAD
187
.077
.076
.074
.073
2
FORSYTH
WINSTON-SALEM
37-067-1008
3656 PIEDMONT MEMORIAL
208
.081
.076
.074
.074
2
FORSYTH
DRIVE
WINSTON-SALEM
37-069-0001
431 S. HILLBOROUGH ST
212
.081
.075
.074
.072
1
FRANKLIN
FRANKLINTON
37-075-0001
FOREST ROAD 423 SPUR
201
.077
.075
.075
.074
1 30
SITE NUMBER
ADDRESS
VALID
DAYS
VALID DAILY 8-HR MAXIMUM
N0. VALUES
COUNTY
.>.075
1st
2nd
3rd
4th
MEAS
GRAHAM
KILMER
37-077-0001
WATER TREATMENT PLANT
211
.088
.075
.073
.072
1
GRANVILLE
JOHN UMSTEAD HOSPITAL
BUTNER
37-081-0013
205 WILOUGHBY
214
.082
.080
.080
.076
4
GUILFORD
GREENSBORO
37-087-0008
2236 ASHEVILLE ROAD
207
.069
.067
.066
.065
0
HAYWOOD
WAYNESVILLE
37-087-0035
TOWER BLUE RIDGE PARKWAY
170
.076
.071
.070
.070
1
HAYWOOD
MILE MARKER 410
37-087-0036
GREAT SMOKY MOUNTAIN
209
.077
.072
.067
.066
1
HAYWOOD
NATIONAL PARK
37-099-0005
BARNET KNOB FIRETOWER RD
208
.078
.073
.071
.071
1
JACKSON
CHEROKEE
37-101-0002
1338 JACK ROAD
214
.081
.075
.075
.074
1
JOHNSTON
CLAYTON
37-107-0004
CORNER HWY 70 EAST
207
.072
.072
.071
.069
0
LENOIR
KINSTON
37-109-0004
1487 RIVERVIEW ROAD
211
.079
.078
.078
.077
6
LINCOLN
LINCOLNTON
37-113-9991
USDA SOUTHERN RESEARCH
184
.069
.067
.066
.066
0
MACON
STATION
COWEETA
37-117-0001
1210 HAYES STREET
206
.074
.070
.067
.066
0
MARTIN
JAMESVILLE
37-119-0041
1130 EASTWAY DRIVE
209
093
.091
.088
.088
14
MECKLENBURG
CHARLOTTE
37-119-1005
400 WESTINGHOUSE BLVD.
211
.090
.087
.086
.082
6
MECKLENBURG
CHARLOTTE
37-119-1009
29 N @ MECKLENBURG CAB
212
.088
.087
.084
.083
13
MECKLENBURG
CO
CHARLOTTE
37-123-9991
136 PERRY DR
206
.074
.069
.069
.069
0
MONTGOMERY
CANDOR
37-129-0002
6028 HOLLY SHELTER RD
208
.065
.064
.064
.064
0
NEW HANOVER
CASTLE HAYNE
37-145-0003
STATE HIGHWAY 49 SOUTH
213
.083
.073
.073
.072
1
PERSON
ROXBORO
37-147-0006
403 GOVERNMENT CIRCLE
207
.081
.077
.077
.074
3
PITT
GREENVILLE
37-157-0099
6371 NC 65 @ BETHANY SCHOOL
212
.079
.077
.074
.071
2
ROCKINGHAM
BETHANY
37-159-0021
301 WEST ST & GOLD HILL AVE
211
.085
.079
.078
.077
8
ROWAN
ROCKWELL
31
SITE NUMBER
ADDRESS
VALID
DAYS
VALID DAILY 8-HR MAXIMUM
N0. VALUES
COUNTY
.>.075
1st
2nd
3rd
4th
MEAS
37-159-0022
925 N ENOCHVILLE AVE
211
.089
.080
.078
.078
6
ROWAN
ENOCHVILLE
37-173-0002
CENTER STREET
207
.062
.061
.060
.060
0
SWAIN
PARKS 7 REC FACILITY
37-179-0003
701 CHARLES STREET
207
.078
.078
.075
.073
2
UNION
MONROE
37-183-0014
3801 SPRING FOREST ROAD
214
.079
.078
.078
.074
3
WAKE
RALEIGH
37-183-0016
201 NORTH BROAD STREET
214
.088
.084
.079
.078
6
WAKE
FUQUAY-VARINA
37-199-0004
4666 STATE HIGHWAY 128
189
.078
.076
.074
.071
2
YANCEY
BURNSVILLE
Total Samples
9,275
100
Total Sites Sampled
45
Figure 5.12 Ozone: Mean Annual Fourth Highest 8-Hour Average, 2009-2011 32
5.5 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 2011. Some SO2 sites are operated only every third year. We supplemented this report with one monitor that operated last in 2010 and one monitor that operated last in 2009.
From the 10 sites with SO2 data obtained between 2009 and 2011, 66,242 valid hourly averages were collected. A map of the active SO2 sampling sites is presented in Figure 5.13, and a detailed summary of the data from each site is given in Table 5.5.
The highest annual arithmetic mean was 1.50 ppb. The highest maximum 24-hour average was 9.3 ppb.
There was 1 day (7/ 2/ 2011) on which the maximum daily concentration exceeded the level of the 99th percentile standard. The concentration was 79 ppb at monitoring site at Highway 421 North, Wilmington.
The size of an urban area appears to have no significant effect on 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.
Figure 5.13 Locations of Sulfur Dioxide Monitoring Sites in 2009, 2010 and 2011 33
Figure 5.14 Sulfur Dioxide Design Values by County, 2009-2011
Table 5.5 Sulfur Dioxide in Parts Per Billion from All Sites for 2009-2011
SITE NUMBER
ADDRESS
NUM OBS
ONE-HOUR MAXIMA
24-HOUR MAXIMA
99thPER-
CENTILE
ARITH MEAN
COUNTY
1st
2nd
1st
2nd 2011
37-013-0007
1645 SANDY LANDING
581
21.0
9.0
3.5
2.3
21.0
1.13
BEAUFORT
AURORA
37-013-0151
BEAUFORT
229 NC HWY 306 N
BATH
7,475
32.0
31.0
6.2
4.7
26.0
.63
37-037-0004
325 RUSSETT RUN ROAD
8,274
20.0
18.0
5.9
4.3
13.0
.79
CHATHAM
PITTSBORO
37-067-0022
1300 BLK. HATTIE AVE
8,704
13.8
10.7
3.8
3.5
9.0
.50
FORSYTH
WINSTON-SALEM
37-119-0041
MECKLENBURG
1130 EASTWAY DRIVE
CHARLOTTE
8,406
21.6
21.2
4.9
3.3
14.5
.60 37-129-0006 HIGHWAY 421 NORTH 8,054 76.0 69.0 9.3 7.8 54.0 1.50 NEW HANOVER WILMINGTON 34
SITE NUMBER
ADDRESS
NUM OBS
ONE-HOUR MAXIMA
24-HOUR MAXIMA
99thPER-
CENTILE
ARITH MEAN
COUNTY
1st
2nd
1st
2nd 37-157-0099 ROCKINGHAM 6371 NC 65 @ BETHANY REIDSVILLE 8,110 23.0 18.0 4.5 4.4 18.0 1.28 37-183-0014 WAKE 3801SPRING FOREST RD. RALEIGH 8,258 18.0 16.3 3.8 3.7 12.7 .68 Total Samples 49,752 Total Sites Sampled 8 2010
37-117-0001
1210HAYES STREET
8,176
10.0
8.0
3.3
3.1
6.0
.45
MARTIN
JAMESVILLE
Total Samples
8,176
Total Sites Sampled
1
2009
37-051-1003
3625 GOLFVIEW RD
8,314
11.0
10.0
4.3
4.2
10.0
1.11
CUMBERLAND
HOPE MILLS
Total Samples
8,314
Total Sites Sampled
1
35
Figure 5.15 Sulfur Dioxide: Second Highest 1-Hour Averages in the Most Recent Year of Data from 2009, 2010 or 2011
Figure 5.16 Sulfur Dioxide: Second Highest 24-Hour Averages in the Most Recent Year of Data from 2009, 2010 or 201136
5.7 Nitrogen Dioxide
Nitrogen dioxide (NO2) concentrations were measured using EPA reference or equivalent continuous monitors in 2011 at local program sites in Forsyth and Mecklenburg counties.
From these two sites, 16,464 hourly NO2 measurements were reported. The 98th percentile concentrations and the annual arithmetic means of the 2011 NO2 data are given in Table 5.6. A map of the NO2 sampling sites is presented in Figure 5.17.
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 5.6) are about 19 percent of the annual standard, and the 98th percentile values are about 43 percent of the daily standard.
Figure 5.17 Location of Nitrogen Dioxide Monitoring Sites
Table 5.6 Nitrogen Dioxide in Parts Per Billion for 2011
SITE NUMBER
ADDRESS
NUM OBS
ONE-HOUR MAXIMA
98th
PERCENTILE
ARITH MEAN
COUNTY
1ST
2ND
37-067-0022
1300 BLK. HATTIE AVENUE
7,978
49.0
46.0
43.0
7.72
FORSYTH
WINSTON-SALEM
37-119-0041
1130 EASTWAY DRIVE
8,486
44.0
43.0
42.0
10.09
MECKLENBURG
CHARLOTTE
Total Samples
16,464
Total Sites Sampled
2
37
5.8 Lead
The state and local program agencies have not performed routine analysis of ambient lead (Pb) in North Carolina since 1982. Pb monitoring was discontinued as a result of the low measurements and a continuing decrease in the Pb concentrations being reported. The decrease in ambient Pb concentrations is due to the reduction and elimination of leaded gasoline, resulting in greatly reduced Pb 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. The purpose of these sites was to gather background information about Pb and other metals. No Pb sites operated in 2011.
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. Pb, 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 Pb 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.
5.8.2 Future Lead Monitoring
As a result of revised federal standards and monitoring requirements, Pb sampling will resume in 2012. Pb will be monitored at 3801 Spring Forest Rd., Raleigh in Wake County and 1130 Eastway Drive, Charlotte in Mecklenburg County.
38
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, in which 100 corresponds to the EPA primary standard for a 24-hour average (8-hour CO average, 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.
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.
In 2011, 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 39
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.ncair.org/monitor).
In this printed report, we have summarized AQI statistics for ten metropolitan areas in North Carolina. (Note: finalized AQI statistics may differ from the forecasts that were reported daily during the year.) Table 6.1 shows the number of days in each health category at each area. AQI statistics for areas other than those reported below are available from the Ambient Monitoring Section on request. (In Table 6.1, the Greenville and Rocky Mount areas have two entries, “actual” and “adjusted”, because AQI monitoring intentionally occurred only every third day during the months before and after ozone monitoring season (i.e., before April and after October). The adjusted entry gives our estimate of the number of days that would have occurred in each category, had all 151 days of these months been monitored. We do not similarly adjust for missing days in April through October, because these days are not numerous and not intentionally planned.) AQI statistics for areas other than those reported below are available from the Ambient Monitoring Section on request.
In the Asheville metropolitan area consisting of Buncombe and Madison counties, the AQI was not “unhealthy for sensitive groups” or “unhealthy” for any of the 364 days monitored.
Figure 6.1 shows summaries of the numbers of days each respective pollutant was responsible for the AQI, and Figure 6.2 shows the number of days the AQI was in each respective health category, for Asheville in 2011.
In the Charlotte-Gastonia-Rock Hill metropolitan area consisting of Cabarrus, Gaston, Lincoln, Mecklenburg, Rowan and Union counties, the AQI was “unhealthy for sensitive groups” or “unhealthy” on 24 out of 365 days monitored. All 24 of these days occurred between June and September.
Figure 6.3 shows summaries of the numbers of days each respective pollutant was responsible for the AQI, and Figure 6.4 shows the number of days the AQI was in each respective health category for Charlotte-Gastonia-Rock Hill in 2011.
In the Fayetteville metropolitan area consisting of Cumberland County, the AQI was “unhealthy for sensitive groups” or “unhealthy” on four out of 365 days monitored. All four of these days occurred in June.
Figure 6.5 shows summaries of the numbers of days each respective pollutant was responsible for the AQI, and Figure 6.6 shows the number of days the AQI was in each respective health category for Fayetteville in 2011.
In the Goldsboro metropolitan area consisting of Wayne County, the AQI was “unhealthy for sensitive groups” or “unhealthy” on two out of 346 days monitored. All two of these days occurred between June and July.
Figure 6.7 shows summaries of the numbers of days each respective pollutant was responsible for the AQI, and Figure 6.8 shows the number of days the AQI was in each respective health category for Goldsboro.
40
In the Greensboro–Winston-Salem–High Point metropolitan area consisting of Alamance, Davidson, Davie, Forsyth, Guilford, Randolph, Stokes and Yadkin counties, the AQI was “unhealthy for sensitive groups” or “unhealthy” on eight out of 365 days monitored. All eight of these days occurred between June and July.
Figure 6.9 shows summaries of the numbers of days each respective pollutant was responsible for the AQI, and Figure 6.10 shows the number of days the AQI was in each respective health category for Greensboro–Winston-Salem–High Point in 2011.
In the Greenville metropolitan area consisting of Pitt County, during January through March PM2.5 monitors operated on 30 of the 90 days; during April through October, PM2.5 and ozone monitors operated on 209 of the 214 days; and in November and December, PM2.5 monitors operated on 61 of the 61 days. The AQI was “unhealthy for sensitive groups” or “unhealthy” for three out of the 290 days monitored. All two of these days occurred between June and July.
Figure 6.11 shows summaries of the numbers of days each respective pollutant was responsible for the AQI, and Figure 6.12 shows the number of days the AQI was in each respective health category for Greenville in 2011 (based on adjusting the January-March, November and December counts to total 151 days instead of 91 days).
In the Hickory-Morganton-Lenoir metropolitan area consisting of Alexander, Burke, Caldwell and Catawba counties, the AQI was not “unhealthy for sensitive groups” or “unhealthy” for any of the 365 days monitored.
Figure 6.13 shows summaries of the numbers of days each respective pollutant was responsible for the AQI, and Figure 6.14 shows the number of days the AQI was in each respective health category for Hickory-Morganton-Lenoir in 2011.
In the Raleigh-Durham-Chapel Hill metropolitan area consisting of Chatham, Durham, Franklin, Johnston, Orange and Wake counties, the AQI was “unhealthy for sensitive groups” or “unhealthy” for six out of the 365 days monitored. All six of these days occurred between June and July.
Figure 6.15 shows summaries of the numbers of days each respective pollutant was responsible for the AQI, and Figure 6.16 shows the number of days the AQI was in each respective health category for Raleigh-Durham-Chapel Hill in 2011.
In the Rocky Mount metropolitan area consisting of Edgecombe and Nash counties, during January through March PM2.5 monitors operated on 29 of the 90 days; during April through October, PM2.5 and ozone monitors operated on 213 of the 209 days; and in November and December, PM2.5 monitors operated on 61 of the 61 days. The AQI was “unhealthy for sensitive groups” or “unhealthy” for two out of the 336 days monitored. All two of these days occurred between June and July.
Figure 6.17 shows summaries of the numbers of days each respective pollutant was responsible for the AQI, and Figure 6.18 shows the number of days the AQI was in each respective health category for Rocky Mount in 2011 (based on adjusting the January-March, November and December counts to total 151 days instead of 90 days).
In the Wilmington metropolitan area consisting of Brunswick and New Hanover 41
counties, the AQI was “unhealthy for sensitive groups” or “unhealthy” on two out of the 362 days monitored. These days occurred in July.
Figure 6.19 shows summaries of the numbers of days each respective pollutant was responsible for the AQI, and Figure 6.20 shows the number of days the AQI was in each respective health category for Wilmington in 2011.
Table 6.1 Air Quality Index Category Days in the Major Metropolitan Areas, 2011
AREA
STATISTICALTREATMENT
GOOD
MODERATE
UNHEALTHY FOR SENSITIVE GROUPS
UNHEALTHY
Asheville
actual
310
54
0
0
Charlotte
actual
223
118
24
0
Fayetteville
actual
284
77
4
0
Goldsboro
actual
302
42
2
0
Greensboro
actual
244
113
8
0
Greenville
actual
214
43
3
0
Greenville
adjusted
242
45
3
0
Hickory
actual
284
81
0
0
Raleigh
actual
257
102
6
0
Rocky Mount
actual
249
48
2
0
Rocky Mount
adjusted
283
51
2
0
Wilmington
actual
311
49
2
0
42
Figure 6.1 Daily Air Quality Index Values for Asheville, 2011
Figure 6.2 Daily Air Quality Index Summary for Asheville, 2011
0
50
100
150
200
250
CO
O3
SO2
NO2
PM2.5
PM10
Days Per Main Pollutant
0
50
100
150
200
250
300
350
Good
Moderate
UnhealthySensitive
Unhealthy
Very Unhealthy
Hazardous
Days Per Health Category 43
Figure 6.3 Daily Air Quality Index Values for Charlotte-Gastonia, 2011
Figure 6.4 Daily Air Quality Index Summary for Charlotte-Gastonia, 2011
0
50
100
150
200
250
CO
O3
SO2
NO2
PM2.5
PM10
Days Per Main Pollutant
0
50
100
150
200
250
Good
Moderate
UnhealthySensitive
Unhealthy
Very Unhealthy
Hazardous
Days Per Health Category 44
Figure 6.5 Daily Air Quality Index Values for Fayetteville, 2011
Figure 6.6 Daily Air Quality Index Summary for Fayetteville, 2011
0
50
100
150
200
250
CO
O3
SO2
NO2
PM2.5
PM10
Days Per Main Pollutant
0
50
100
150
200
250
300
Good
Moderate
UnhealthySensitive
Unhealthy
Very Unhealthy
Hazardous
Days Per Health Category 45
Figure 6.7 Daily Air Quality Index Values for Goldsboro, 2011
Figure 6.8 Daily Air Quality Index Summary for Goldsboro, 2011
0
50
100
150
200
250
300
350
400
CO
O3
SO2
NO2
PM2.5
PM10
Days Per Main Pollutant
0
50
100
150
200
250
300
350
Good
Moderate
UnhealthySensitive
Unhealthy
Very Unhealthy
Hazardous
Days Per Health Category 46
Figure 6.9 Daily Air Quality Index Values for Greensboro-Winston-Salem-
High Point, 2011
Figure 6.10 Daily Air Quality Index Summary for Greensboro-Winston-Salem-
High Point, 2011
0
50
100
150
200
250
CO
O3
SO2
NO2
PM2.5
PM10
Days Per Main Pollutant
0
50
100
150
200
250
300
Good
Moderate
UnhealthySensitive
Unhealthy
Very Unhealthy
Hazardous
Days Per Health Category 47
Figure 6.11 Daily Air Quality Index Values for Greenville, 2011
Figure 6.12 Daily Air Quality Index Summary for Greenville, 2011
0
50
100
150
200
250
CO
O3
SO2
NO2
PM2.5
PM10
Days Per Main Pollutant
0
50
100
150
200
250
300
Good
Moderate
UnhealthySensitive
Unhealthy
Very Unhealthy
Hazardous
Days Per Health Category 48
Figure 6.13 Daily Air Quality Index Values for Hickory-Morganton-Lenoir, 2011
Figure 6.14 Daily Air Quality Index Summary for Hickory-Morganton-Lenoir, 2011
0
50
100
150
200
250
CO
O3
SO2
NO2
PM2.5
PM10
Days Per Main Pollutant
0
50
100
150
200
250
300
Good
Moderate
UnhealthySensitive
Unhealthy
Very Unhealthy
Hazardous
Days Per Health Category 49
Figure 6.15 Daily Air Quality Index Values for Raleigh-Durham-Chapel Hill, 2011
Figure 6.16 Daily Air Quality Index Summary for Raleigh-Durham-Chapel Hill, 2011
0
50
100
150
200
250
CO
O3
SO2
NO2
PM2.5
PM10
Days Per Main Pollutant
0
50
100
150
200
250
300
Good
Moderate
UnhealthySensitive
Unhealthy
Very Unhealthy
Hazardous
Days Per Health Category 50
Figure 6.17 Daily Air Quality Index Values for Rocky Mount, 2011
Figure 6.18 Daily Air Quality Index Summary for Rocky Mount, 2011
0
20
40
60
80
100
120
140
160
CO
O3
SO2
NO2
PM2.5
PM10
Days Per Main Pollutant
0
50
100
150
200
250
300
Good
Moderate
UnhealthySensitive
Unhealthy
Very Unhealthy
Hazardous
Days Per Health Category 51
Figure 6.19 Daily Air Quality Index Values for Wilmington, 2011
Figure 6.20 Daily Air Quality Index Summary for Wilmington, 2011
0
20
40
60
80
100
120
140
160
180
200
CO
O3
SO2
NO2
PM2.5
PM10
Days Per Main Pollutant
0
50
100
150
200
250
300
350
Good
Moderate
UnhealthySensitive
Unhealthy
Very Unhealthy
Hazardous
Days Per Health Category 52
7 Acid Rain
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.
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.
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 2011, 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.
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 2011 ranged from 4.97 to 5.35 with a mean of 5.06. The 2011 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.
53
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.
Figure 7.1 Annual Mean pH Values at North Carolina NADP Sites, 2011
54
Table 7.1 pH, Conductivity in Microsiemans per Centimeter and Precipitation in Inches from the National Atmospheric Deposition Program for 2011
County
Site ID
Address
pH
Conductivity
Precipitation
Bertie
NC03
Lewiston
4.97
9.95
43.33
Carteret
NC06
Beaufort
5.07
12.90
40.13
Macon
NC25
Coweeta
5.11
6.21
71.98
Rowan
NC34
Piedmont Research Station
5.02
9.25
44.83
Sampson
NC35
Clinton Crops Research Station
5.35
8.54
36.83
Scotland
NC36
Jordan Creek
4.95
9.34
38.97
Wake
NC41
Finley Farm
5.12
8.71
37.75
Yancey
NC45
Mt. Mitchell
5.02
6.20
71.22
Sevier (TN)
TN11
Great Smoky Mountains National Park-Elkmont
4.97
7.46
65.81
55
Table 7.2 Ion Concentrations in Milligrams per Liter (Precipitation-weighted Annual Means) from the National Atmospheric Deposition Program Data for 2011
County
Site ID
% Complete-ness
Ca
Mg
K
Na
NH4
NO3
Cl
SO4
Bertie
NC03
87
0.096
0.032
0.039
0.190
0.360
0.799
0.334
0.908
Beaufort
NC06
74
0.105
0.113
0.046
0.911
0.225
0.565
1.608
0.814
Macon
NC25
92
0.073
0.018
0.021
0.103
0.158
0.437
0.176
0.542
Rowan
NC34
83
0.082
0.021
0.080
0.107
0.444
0.730
0.186
.908
Sampson
NC35
93
0.081
0.037
0.027
0.263
0.517
0.696
0.466
0.828
Scotland
NC36
89
0.094
0.031
0.024
0.209
0.278
0.718
0.364
0.795
Wake
NC41
96
0.076
0.031
0.054
0.203
0.399
0.685
0.357
0.825
Yancey
NC45
77
0.055
0.010
0.014
0.043
0.155
0.388
0.073
0.553
Sevier (TN)
TN11
87
0.089
0.014
0.024
0.040
0.170
0.589
0.072
0.666
56
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. 57
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 became 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 2012.
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. 58
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 state and local programs in NC used two kinds of samplers to acquire PM2.5 mass and its chemical composition: MetOne SASS monitors and URG 3000N monitors. A program operated by federal government agencies, the Interagency Monitoring of Protected Visual Environments, used their own sampling system, called the IMPROVE monitor.
The MetOne SASS monitor measures PM2.5 mass and the chemical composition of PM2.5 (sulfates, nitrates, and metals). This is known as PM2.5 chemical speciation. The MetOne SASS utilizes four 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 organic carbon and soot-like carbon are collected using the URG 3000N sampler, which is the same method as used for IMPROVE using quartz filters and thermal optical reflective (TOR) analysis.
59
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.
State and local program data are validated on a monthly basis when reports are received from the contract laboratory RTI International.
NCDAQ and the local programs collected data at seven sites using MetOne SASS and the URG 3000N methods, the National Park Service collected at three sites during 2011 using the IMPROVE method. Figure 8.1 shows a map of all these sites. Table 8.1 identifies the sites.
Nitrate samples in 2011 are summarized in Table 8.2 and 8.3. The highest
concentration observed was 5.68 μg/m3
at Charlotte.
Sulfate samples in 2011 are summarized in Table 8.4 and 8.5. The highest concentration observed was 9.11 μg/m3 at Charlotte.
Ammonium samples in 2011 are summarized in Table 8.6 and 8.7. The
highest concentration observed was 3.36 μg/m3 at Charlotte.
Organic Carbon samples in 2011 are summarized in Table 8.8 and 8.9. The highest concentration observed was 23.60 μg/m3 at Durham.
Elemental Carbon samples in 2011 are summarized in Table 8.10 and 8.11. The highest concentration observed was 1.39 μg/m3 at Hickory.
Crustal Component samples in 2011 are summarized in Table 8.12 and 8.13. The highest concentration observed was 2.43 μg/m3 at Raleigh.
Elemental lead samples for 2011 are summarized in Table 8.14 and 8.15. Out of 832 samples statewide, three samples exceeded 0.01 μg/m3; 829 of these sample concentrations (100 percent) were less than 0.01 μg/m3. One sample was greater than 0.014 μg/m3. The highest concentration observed was 0.021 μg/m3 at Winston-Salem.
60
Figure 8.1 Location of Nitrate, Sulfate, Ammonium, Organic Carbon, Elemental Carbon, Crustal component, Monitoring Sites 2011.
Table 8.1 Fine Particle Speciation Sites Operated in North Carolina in 2011
SITE NUMBER
ADDRESS
COUNTY
37-021-0034
175 BINGHAM ROAD
BUNCOMBE
ASHEVILLE
37-035-0004
1650 1ST STREET
CATAWBA
HICKORY
37-057-0002
S.SALISBURY ST
DAVIDSON
LEXINGTON
37-067-0022
1300 BLK HATTIE AVE
FORSYTH
WINSTON-SALEM
37-119-0041
1130 EASTWAY DRIVE
MECKLENBURG
CHARLOTTE
37-159-0021
301 WEST ST & GOLD HILL AVE
ROWAN
ROCKWELL
37-183-0014
3801 SPRING FOREST RD
WAKE
RALEIGH
SITES OPERATED IN
7
2011
61
Table 8.2 Mean and Maximum Nitrate PM2.5 Concentration for 2011
SITE NUMBER
ADDRESS
NUM OBS
24-HOUR MAXIMA
ARITH MEAN
COUNTY
1st
2nd
3rd
4th
37-021-0034
175 BINGHAM ROAD
58
1.40
1.39
1.16
1.07
.39
BUNCOMBE
ASHEVILLE
37-035-0004
1650 1ST STREET
61
4.55
2.22
1.97
1.90
0.65
CATAWBA
HICKORY
37-057-0002
S.SALISBURY ST
61
3.38
1.79
1.64
1.55
.58
DAVIDSON
LEXINGTON
37-067-0022
1300 BLK HATTIE AVE
50
4.25
1.58
1.43
1.30
.57
FORSYTH
WINSTON-SALEM
37-119-0041
1130 EASTWAY DRIVE
118
5.68
4.87
3.86
2.94
.66
MECKLENBURG
CHARLOTTE
37-159-0021
ROWAN
301 WEST ST & GOLD HILL AVE
59
2.99
2.33
1.62
1.50
.53
ROCKWELL
37-183-0014
3801 SPRING FOREST RD
113
3.00
2.78
2.53
2.45
.55
WAKE
RALEIGH
Total Samples
520
Total Sites Sampled
7
Table 8.3 Nitrate PM2.5 - Quartile statistics - Micrograms/Cubic Meter (LC) for 2011
SITE NUMBER
ADDRESS
NUM OBS
QUARTILES
Mg/m2
MAXIMUM
COUNTY
1st
2nd
3rd
37-021-0034
175 BINGHAM ROAD
58
.21
.30
.44
1.40
BUNCOMBE
ASHEVILLE
37-035-0004
1650 1ST STREET
61
.27
.38
.73
4.55
CATAWBA
HICKORY
37-057-0002
S.SALISBURY ST
61
.26
.40
.72
3.38
DAVIDSON
LEXINGTON
37-067-0022
FORSYTH
1300 BLK HATTIE AVE
50
.26
.36
.62
4.25
WINSTON-SALEM
37-119-0041
MECKLENBURG
1130 EASTWAY DRIVE
118
.23
.34
.70
5.68
CHARLOTTE
62
SITE NUMBER
ADDRESS
NUM OBS
QUARTILES
Mg/m2
MAXIMUM
COUNTY
1st
2nd
3rd
37-159-0021
ROWAN
301 WEST ST & GOLD HILL AVE
59
.23
.34
.64
2.99
ROCKWELL
37-183-0014
WAKE
3801 SPRING FOREST RD
113
.24
.35
.64
3.00
RALEIGH
Effective Sample Count
520
Total Sites Sampled
7
Table 8.4 Mean and Maximum Sulfate PM2.5 Concentration for 2011
SITE NUMBER
ADDRESS
NUM OBS
24-HOUR MAXIMA
ARITH MEAN
COUNTY
1st
2nd
3rd
4th
37-021-0034
175 BINGHAM ROAD
58
8.16
6.77
5.84
5.61
2.51
BUNCOMBE
ASHEVILLE
37-035-0004
1650 1ST STREET
61
7.90
4.92
4.82
4.45
2.27
CATAWBA
HICKORY
37-057-0002
S.SALISBURY ST
61
5.80
4.95
4.88
4.66
2.26
DAVIDSON
LEXINGTON
37-067-0022
1300 BLK HATTIE AVE
50
7.06
5.14
4.68
4.48
2.40
FORSYTH
WINSTON-SALEM
37-119-0041
1130 EASTWAY DRIVE
118
9.11
5.84
5.82
5.50
2.35
MECKLENBURG
CHARLOTTE
37-159-0021
ROWAN
301 WEST ST & GOLD HILL AVE
59
6.09
5.42
5.04
4.61
2.23
ROCKWELL
37-183-0014
3801 SPRING FOREST RD
113
8.22
6.13
5.91
4.93
2.32
WAKE
RALEIGH
Total Samples
520
Total Sites Sampled
7
 Not including collocated samples.
63
Table 8.5 Sulfate PM2.5 - Quartile statistics - Micrograms/Cubic Meter (LC) for
2011
SITE NUMBER
ADDRESS
NUM OBS
QUARTILES
MAXIMUM
COUNTY
1st
2nd
3rd
37-021-0034
175 BINGHAM ROAD
58
1.23
2.33
3.38
8.16
BUNCOMBE
ASHEVILLE
37-035-0004
1650 1ST STREET
61
1.16
2.21
2.92
7.90
CATAWBA
HICKORY
37-057-0002
S.SALISBURY ST
61
1.25
2.15
3.06
5.80
DAVIDSON
LEXINGTON
37-067-0022
FORSYTH
1300 BLK HATTIE AVE
50
1.37
2.24
3.19
7.06
WINSTON-SALEM
37-119-0041
MECKLENBURG
1130 EASTWAY DRIVE
118
1.20
2.01
3.04
9.11
CHARLOTTE
37-159-0021
ROWAN
301 WEST ST & GOLD HILL AVE
59
1.18
1.99
2.92
6.09
ROCKWELL
37-183-0014
WAKE
3801 SPRING FOREST RD
113
1.42
2.02
2.97
8.22
RALEIGH
Effective Sample Count
520
Total Sites Sampled
7
Table 8.6 Mean and Maximum Ammonium Ion PM2.5 Concentration for 2011
SITE NUMBER
ADDRESS
NUM OBS
24-HOUR MAXIMA
ARITH MEAN
COUNTY
1st
2nd
3rd
4th
37-021-0034
175 BINGHAM ROAD
58
1.84
1.58
1.48
1.36
.68
BUNCOMBE
ASHEVILLE
37-035-0004
1650 1ST STREET
61
2.18
2.15
2.11
1.86
.72
CATAWBA
HICKORY
37-057-0002
S.SALISBURY ST
61
2.14
2.05
1.95
1.74
.75
DAVIDSON
LEXINGTON
37-067-0022
1300 BLK HATTIE AVE
50
2.17
2.03
1.95
1.76
.75
FORSYTH
WINSTON-SALEM
 Not including collocated samples.
64
SITE NUMBER
ADDRESS
NUM OBS
24-HOUR MAXIMA
ARITH MEAN
COUNTY
1st
2nd
3rd
4th
37-119-0041
1130 EASTWAY DRIVE
118
3.36
2.40
2.25
1.96
.74
MECKLENBURG
CHARLOTTE
37-159-0021
ROWAN
301 WEST ST & GOLD HILL AVE
59
2.06
1.96
1.72
1.68
.68
ROCKWELL
37-183-0014
3801 SPRING FOREST RD
113
2.22
2.04
1.76
1.68
.73
WAKE
RALEIGH
Total Samples
520
Total Sites Sampled
7
Table 8.7 Ammonium Ion PM2.5 - Quartile statistics - Micrograms/Cubic Meter (LC) for 2011
SITE NUMBER
ADDRESS
NUM OBS
QUARTILES
MAXIMUM
COUNTY
1st
2nd
3rd
37-021-0034
175 BINGHAM ROAD
58
.32
.65
.88
1.84
BUNCOMBE
ASHEVILLE
37-035-0004
1650 1ST STREET
61
.35
65
.94
2.18
CATAWBA
HICKORY
37-057-0002
S.SALISBURY ST
61
.37
.70
.97
2.14
DAVIDSON
LEXINGTON
37-067-0022
FORSYTH
1300 BLK HATTIE AVE
50
.38
.66
.98
2.17
WINSTON-SALEM
KINSTON
37-119-0041
MECKLENBURG
1130 EASTWAY DRIVE
118
.30
.65
.97
3.36
CHARLOTTE
37-159-0021
ROWAN
301 WEST ST & GOLD HILL AVE
59
.30
.59
.89
2.06
ROCKWELL
37-183-0014
WAKE
3801 SPRING FOREST RD
113
.39
.66
.99
2.22
RALEIGH
Effective Sample Count
520
Total Sites Sampled
7
 Not including collocated samples.
65
Table 8.8 Mean and Maximum Organic Carbon CSN PM2.5 Concentration for 2011
SITE NUMBER
ADDRESS
NUM OBS
24-HOUR MAXIMA
ARITH MEAN
COUNTY
1st
2nd
3rd
4th
37-021-0034
175 BINGHAM ROAD
58
5.70
5.21
5.11
4.89
2.37
BUNCOMBE
ASHEVILLE
37-035-0004
1650 1ST STREET
61
7.43
6.42
6.18
5.52
2.99
CATAWBA
HICKORY
37-057-0002
S.SALISBURY ST
58
5.49
5.38
5.11
5.09
2.79
DAVIDSON
LEXINGTON
37-067-0022
1300 BLK HATTIE AVE
36
5.31
5.12
4.70
3.76
2.35
FORSYTH
WINSTON-SALEM
37-063-0099
DURHAM
109 TW ALEXANDER
DRIVE
DURHAM
57
23.60
9.23
6.84
6.49
3.89
37-119-0041
1130 EASTWAY DRIVE
97
7.40
6.53
6.33
5.76
2.95
MECKLENBURG
CHARLOTTE
37-159-0021
ROWAN
301 WEST ST & GOLD HILL AVE
58
6.31
6.24
5.62
5.47
2.68
ROCKWELL
37-183-0014
3801 SPRING FOREST RD
114
8.77
6.74
6.25
6.14
2.88
WAKE
RALEIGH
Total Samples
539
Total Sites Sampled
8
Table 8.9 Organic Carbon CSN PM2.5 - Quartile statistics - Micrograms/Cubic Meter (LC) for 2011
SITE NUMBER
ADDRESS
NUM OBS
QUARTILES
MAXIMUM
COUNTY
1st
2nd
3rd
37-021-0034
175 BINGHAM ROAD
58
1.53
2.31
3.07
5.70
BUNCOMBE
ASHEVILLE
37-035-0004
1650 1ST STREET
61
2.03
2.71
3.87
7.43
CATAWBA
HICKORY
37-057-0002
S.SALISBURY ST
58
1.95
2.63
3.26
5.49
DAVIDSON
LEXINGTON
37-067-0022
FORSYTH
1300 BLK HATTIE AVE
36
1.55
2.16
2.78
5.31
WINSTON-SALEM
66
Table 8.10 Mean and Maximum Elemental Carbon CSN PM2.5 Concentration for 2011
SITE NUMBER
ADDRESS
NUM OBS
24-HOUR MAXIMA
ARITH MEAN
COUNTY
1st
2nd
3rd
4th
37-021-0034
BUNCOMBE
175 BINGHAM ROAD
ASHEVILLE
58
.69
.66
.59
.51
.23
37-035-0004
1650 1ST STREET
61
1.39
1.28
.99
.94
.39
CATAWBA
HICKORY
37-057-0002
S.SALISBURY ST
58
1.24
.89
.56
.54
.31
DAVIDSON
LEXINGTON
37-067-0022
FORSYTH
1300 BLK HATTIE AVE
WINSTON-SALEM
36
.58
.57
.52
.42
.24
37-063-0099
DURHAM
109 TW ALEXANDER
DRIVE
DURHAM
57
.49
.45
.42
.42
.22
37-119-0041
1130 EASTWAY DRIVE
97
.97
.74
.74
.67
.30
MECKLENBURG
CHARLOTTE
37-159-0021
ROWAN
301 WEST ST & GOLD HILL AVE
58
.83
.64
.58
.51
.23
ROCKWELL
37-183-0014
3801 SPRING FOREST RD
114
1.29
.83
.82
.68
.26
WAKE
RALEIGH
Total Samples
539
Total Sites Sampled
8
 Not including collocated samples.
^ These IMPROVE monitors do not report this speciation component
37-063-0099
DURHAM
109 TW ALEXANDER
DRIVE
DURHAM
57
2.42
3.40
4.55
23.60
37-119-0041
MECKLENBURG
1130 EASTWAY DRIVE
97
1.86
2.78
3.78
7.40
CHARLOTTE
37-159-0021
ROWAN
301 WEST ST & GOLD HILL AVE
58
1.69
2.64
3.07
6.31
ROCKWELL
37-183-0014
WAKE
3801 SPRING FOREST RD
114
1.90
2.64
3.52
8.77
RALEIGH
Effective Sample Count
539
Total Sites Sampled
8
67
Table 8.11 Elemental Carbon CSN PM2.5 - Quartile statistics - Micrograms/Cubic Meter (LC) for 2011
 Not including collocated samples.
^ These IMPROVE monitors do not report this speciation component
SITE NUMBER
ADDRESS
NUM OBS
QUARTILES
MAXIMUM
COUNTY
1st
2nd
3rd
37-021-0034
175 BINGHAM ROAD
58
.13
.17
.30
.69
BUNCOMBE
ASHEVILLE
37-035-0004
1650 1ST STREET
61
.21
.30
.47
1.39
CATAWBA
HICKORY
37-057-0002
S.SALISBURY ST
58
.20
.25
.35
1.24
DAVIDSON
LEXINGTON
37-067-0022
FORSYTH
1300 BLK HATTIE AVE
WINSTON-SALEM
36
.15
.21
.27
.58
37-063-0099
DURHAM
109 TW ALEXANDER
DRIVE
DURHAM
57
.15
.20
.25
.49
37-119-0041
MECKLENBURG
1130 EASTWAY DRIVE
97
.17
.24
.38
.97
CHARLOTTE
37-159-0021
ROWAN
301 WEST ST & GOLD HILL AVE
58
.13
.19
.26
.83
ROCKWELL
37-183-0014
WAKE
3801 SPRING FOREST RD
114
.16
.22
.28
1.29
RALEIGH
Effective Sample Count
539
Total Sites Sampled
8
68
Table 8.12 Mean and Maximum Crustal Component PM2.5 Concentration for 2011
SITE NUMBER
ADDRESS
NUM OBS
24-HOUR MAXIMA
ARITH MEAN
COUNTY
1st
2nd
3rd
4th
37-021-0034
BUNCOMBE
175 BINGHAM ROAD
ASHEVILLE
58
1.12
1.07
.84
.71
.32
37-035-0004
1650 1ST STREET
61
1.00
.87
.81
.67
.31
CATAWBA
HICKORY
37-057-0002
S.SALISBURY ST
61
.98
.79
.79
.77
.36
DAVIDSON
LEXINGTON
37-067-0022
FORSYTH
1300 BLK HATTIE AVE
WINSTON-SALEM
51
.77
.71
.57
.54
.25
37-119-0041
1130 EASTWAY DRIVE
118
1.81
1.19
1.00
.99
.38
MECKLENBURG
CHARLOTTE
37-159-0021
ROWAN
301 WEST ST & GOLD HILL AVE
59
1.20
.94
.91
.67
.30
ROCKWELL
37-183-0014
3801 SPRING FOREST RD
113
2.43
1.79
1.13
.96
.36
WAKE
RALEIGH
Total Samples
521
Total Sites Sampled
7
Table 8.13 Crustal Component CSN PM2.5 - Quartile statistics - Micrograms/Cubic Meter (LC) for 2011
SITE NUMBER
ADDRESS
NUM OBS
QUARTILES
MAXIMUM
COUNTY
1st
2nd
3rd
37-021-0034
175 BINGHAM ROAD
58
.16
.27
.39
1.12
BUNCOMBE
ASHEVILLE
37-035-0004
1650 1ST STREET
61
.16
.26
.38
1.00
CATAWBA
HICKORY
37-057-0002
S.SALISBURY ST
61
.19
.35
.49
.98
DAVIDSON
LEXINGTON
37-067-0022
FORSYTH
1300 BLK HATTIE AVE
WINSTON-SALEM
51
.13
.20
.31
.77
37-119-0041
MECKLENBURG
1130 EASTWAY DRIVE
118
.19
.31
.48
1.81
CHARLOTTE
69
SITE NUMBER
ADDRESS
NUM OBS
QUARTILES
MAXIMUM
COUNTY
1st
2nd
3rd
37-159-0021
ROWAN
301 WEST ST & GOLD HILL AVE
59
.14
.24
.40
1.20
ROCKWELL
37-183-0014
WAKE
3801 SPRING FOREST RD
113
.20
.29
.43
2.43
RALEIGH
Effective Sample Count
521
Total Sites Sampled
7
Table 8.14 Mean and Maximum Lead PM2.5 Concentration for 2011
 Not including collocated samples.
SITE NUMBER
ADDRESS
NUM
OBS
24-HOUR MAXIMA
ARITH
MEAN
COUNTY
1st
2nd
3rd
4th
37-021-0034
175 BINGHAM ROAD
58
.006
.004
.003
.003
.0008
BUNCOMBE
ASHEVILLE
37-035-0004
1650 1ST. ST
61
.009
.006
.006
.006
.0015
CATAWBA
HICKORY
37-057-0002
S.SALISBURY ST
61
.011
.006
.005
.005
.0013
DAVIDSON
LEXINGTON
37-067-0022
1300 BLK. HATTIE AVENUE
51
.021
.013
.008
.006
.0021
FORSYTH
WINSTON-SALEM
37-119-0041
1130 EASTWAY DRIVE
118
.007
.006
.006
.006
.0014
MECKLENBURG
CHARLOTTE
37-159-0021
ROWAN
301 WEST ST & GOLD HILL AVE
59
.008
.005
.005
.004
.0012
ROCKWELL
37-183-0014
3801 SPRING FOREST RD
113
.006
.005
.005
.005
.0002
WAKE
RALEIGH
Total Samples
521
Total Sites Sampled
7
70
Table 8.15 Lead PM2.5 - Quartile statistics - Micrograms/Cubic Meter (LC) for 2011
SITE NUMBER
ADDRESS
NUM OBS
QUARTILES
MAXIMUM
COUNTY
1st
2nd
3rd
37-021-0034
BUNCOMB