Appendix A: Description of Methodology

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 PM_2.5 concentration information for the 3-year period for 2002-2004 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 received from EPA October 12, 2005 in personal correspondence from Mark Schmidt, EPA.

Ozone Data Analysis
The 2002, 2003, and 2004 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 2002, 2003, and 2004, 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 EPA Air 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. Multiple monitor readings on the same day in the same county counted as only one day.

Short-term Particle Pollution Data Analysis
A.S.L. & Associates identified the maximum daily 24-hour AQS PM_2.5 concentration for each county in 2002, 2003, and 2004 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 PM_2.5 concentration was within the ranges identified by EPA based on the EPA Air Quality Index:

from 0.0 µg/m3 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 only FRM and FEM methods, which reported 24-h averaged data. As instructed by the Lung Association, A.S.L. & Associates included the exceptional and natural events that were identified in the database and identified for the Lung Association the dates and monitoring sites that experienced such events.

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. Multiple monitor readings on the same day in the same county counted as only one day.