September 2013: American Lung Association Report, State of the Air

This is the thirteenth article in a series about air quality in general and how it applies to Indiana. This article will discuss the American Lung Association report called State of the Air.

For several years the American Lung Association (ALA) has released a report called State of the Air. The latest was released in April of this year. The report looks at the most recent three years of ozone and fine particle (PM-2.5) data for the nation. The 2013 report looks at data for 2009 – 2011. The report provides a letter grade for each county (A – F) based upon a grading scale that the ALA developed. This is the problem. The grading scale is not consistent with the form of the national ambient air quality standards and inflates the severity of air quality problems. Counties that meet the national ambient air quality standards are often shown as getting an “F” from the ALA report.

For the annual PM-2.5 standard, ALA compared the 2009-2011 design values with an annual standard of 12.0 micrograms per cubic meter (ug/m3). This standard was issued by the United States Environmental Protection Agency (U.S. EPA) in December of 2012. It does not take effect until the spring of 2015. It does not apply to air quality data taken in the 2009 – 2011 time period. The appropriate standard to compare against would have been the 15.0 ug/m3 standard that was in effect when the data were measured.

The problem is even worse for short term standards. To show compliance with the 8-hour ozone standard, U.S. EPA outlines that the fourth highest values for each year are averaged and this value compared to the standard of 0.075 parts per million (ppm). This analysis is done on a monitor by monitor basis and the highest monitor in a county is used to determine whether a county is attainment or nonattainment.

The ALA looks at all days that are above the standard, regardless of which site they are measured at. So for example, if two sites have three days each that exceed the standard, that occur on different days, the ALA considers this six exceedance days and grades the area based on six violation days. By U.S. EPA methods, each monitoring site is allowed three exceedances and would be considered as meeting the standard. The ALA further weights the days depending upon how much they are above the standard. Using the U.S. EPA Air Quality Index, the ALA weights red days by a factor of 1.5, purple days by a factor of 2 and maroon days by a factor of 2.5. The U.S. EPA method does not use weighting.

One way for a county to improve their rating with the ALA would be to reduce the number of monitors. U.S. EPA sets minimum requirements for how many monitors an area must install. In many cases this is one monitor. Some areas decide to do a better job and add additional monitors to provide better coverage. The ALA rewards this by summing exceedances from all monitors to judge the attainment status of a county. Shutting down monitors would improve the chances that an area would not have extra exceedances and would improve the grade from the ALA. However, many areas would not have as good of coverage of monitoring data. Penalizing an area for going above U.S. EPA’s minimum sampling requirement is not a good policy.

The following example illustrates the application of the ALA method. This example has two ozone monitors. Shown are the top four ozone values and the dates of each and the AQI rating.

Application of the ALA Method
Year Date Ozone AQI Date Ozone AQI
2009 1 06/30/2009 0.100 Red 06/29/2009 0.093 Orange
2 07/04/2009 0.090 Orange 07/05/2009 0.089 Orange
3 08/03/2009 0.085 Orange 08/02/2009 0.076 Orange
4 07/06/2009 0.074 Yellow 08/04/2009 0.072 Yellow
2010 1 07/05/2010 0.096 Red 07/04/2010 0.092 Orange
2 06/25/2010 0.088 Orange 06/24/2010 0.090 Orange
3 07/02/2010 0.080 Orange 07/03/2010 0.085 Orange
4 08/15/2010 0.073 Yellow 08/14/2010 0.070 Yellow
2011 1 07/11/2011 0.095 Orange 07/12/2011 0.090 Orange
2 07/02/2011 0.086 Orange 07/01/2011 0.085 Orange
3 07/03/2011 0.080 Orange 07/04/2011 0.080 Orange
4 08/05/2011 0.072 Yellow 08/10/2011 0.075 Yellow
DV 0.073 0.072
  • Orange Days: 15 (weighting factor 1) = 15
  • Red Days: 2 (weighting factor 1.5) = 3
  • Total 18 / 3 = 6.0, Rating F

The ALA grading system would give this county an F while the U.S. EPA official rating would be attainment. Explaining the difference to the public is never an easy task.

Keith Baugues