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Appendix A: Description of Methodology
Statistical Methodology: The Air Quality Data
Data Sources
The data on air quality throughout the United States were obtained from the U.S. Environmental Protection Agency’s Air Quality System (AQS), formerly called Aerometric Information Retrieval System (AIRS) database. The American Lung Association contracted with Dr. Allen S. Lefohn, A.S.L. & Associates, Helena, Montana, to characterize the hourly averaged ozone concentration information and the 24-hour averaged PM2.5 concentration information for the 3-year period for 2001-2003 for each monitoring site.
Design values for the annual PM 2.5 concentrations by county were collected from data previously summarized by EPA and were used as obtained from EPA’s Office of Air Quality Planning and Standards on February 1, 2005. (Communication from Mark Schmidt).
Ozone Data Analysis
The 2001, 2002, and 2003 AQS hourly ozone data were used to calculate the daily 8-hour maximum concentration for each ozone-monitoring site. The data were considered for a 3-year period for the same reason that EPA uses 3 years of data to determine compliance with the ozone: to prevent a situation in any single year, where anomalies of weather or other factors create air pollution levels, which inaccurately reflect the normal conditions. The highest 8-hour daily maximum concentration in each county for 2001, 2002, and 2003, based on the EPA defined ozone season, was identified.
Using these results, A.S.L. & Associates prepared a table by county that summarized, for each of the 3 years, the number of days the ozone level was within the ranges identified by EPA based on the EPAAir Quality Index:
0.000 – 0.064 ppm Good (Green)
0.065 – 0.084 ppm Moderate (Yellow)
0.085 – 0.104 ppm Unhealthy for Sensitive Groups (Orange)
0.105 – 0.124 ppm Unhealthy (Red)
0.125 – 0.374 ppm Very Unhealthy (Purple)
No data capture criteria were used to eliminate monitoring sites. All data within the ozone season were used in the analysis because it was the goal to identify the number of days that 8-hour daily maximum concentrations occurred within the defined ranges.
Following receipt of the above information, the American Lung Association identified the number of days each county, with at least one ozone monitor, experienced air quality designated as orange, red, or purple.
Short-term Particle Pollution Data Analysis
A.S.L. & Associates identified the maximum daily 24-hour AIRS PM 2.5 concentration for each county in 2001, 2002, and 2003 with monitoring information. Using these results, A.S.L. & Associates prepared a table by county that summarized, for each of the 3 years, the number of days the maximum of the daily PM2.5 concentration was within the ranges identified by EPA based on the EPA Air Quality Index:
from 0.0 µg/m 3 to 15.4 µg/m3 Good (Green)
from 15.5 µg/m3 to 40.4 µg/m3 Moderate (Yellow)
from 40.5 µg/m3 to 65.4 µg/m3 Unhealthy for Sensitive Groups (Orange)
from 65.5 µg/m3 to 150.4 µg/m3 Unhealthy (Red)
from 150.5 µg/m3 to 250.4 µg/m3 Very Unhealthy (Purple)
greater than or equal to 250.5 µg/m3 Hazardous (Maroon)
No data capture criteria were used to eliminate monitoring sites. All data were used in the analysis because it was the goal to identify the number of days that the maximum in each county of the daily AIRS PM 2.5 concentration occurred within the defined ranges. Only 24-h averaged PM data were used. Included in the analysis are data collected using non-FRM methods, which reported 24-h averaged data.
Following receipt of the above information, the American Lung Association identified the number of days each county, with at least one PM 2.5 monitor, experienced air quality designated as orange, red, or purple.
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