Recent changes in one of the U.S. Environmental Protection Agency’s National Ambient Air Quality Standards will most likely reduce the number of days that the air in Pima County is categorized as “good” on the Air Quality Index. The changes are based on EPA’s review of thousands of studies and make the air quality standard for fine particulate matter (2.5 microns or less in size) more protective of public health.

Exposure to fine particulate pollution, also known as PM2.5, can cause premature death and harmful cardiovascular effects such as heart attacks and strokes. In addition, particulate pollution causes haze and obscures mountain views. PM2.5 can be emitted directly from a variety of sources, including gasoline- and diesel-powered vehicles, smokestacks, fires, power plants, and industrial processes.

“Last year under the old standard, there were 361 days classified as ‘good’ days for PM2.5. With the new standard, some of those good air days will become ‘moderate,’ said Beth Gorman, Pima County Department of Environmental Quality’s (PDEQ) Clean Air Program Manager. “It is not that there is more pollution in our air now; rather it is that the new, stricter standards will provide a warning at the lower, more protective level where air pollution amounts could be harmful to our health,” Gorman continued. PDEQ estimates that there may be about a nine percent decrease in the number of “good” air quality days with the new standard. (See graphs in slideshow above.)

The Air Quality Index (AQI) converts air pollution concentrations to a number on a scale from 0 to 500, where “Good” is 0-50, “Moderate” is 51-100, and “Unhealthy for Sensitive Groups” is 101-150. “Even with this change to make the standard more stringent, the majority of our days will still be classified as ‘good’ for all the air pollutants we monitor. This is especially beneficial in a community such as ours where there are many people at risk when air pollution levels are elevated,” Gorman said.

PDEQ monitors fine particulate matter at six different monitoring locations throughout eastern Pima County. Up-to-the-hour air quality information can be obtained at http://www.AirInfoNow.org. Additional information regarding the EPA’s decision to revise the Air Quality Standard for PM2.5 and the recently issued formula forthe Air Quality Index can be found at http://www.epa.gov/pm/actions.html#dec12

via Changes in EPA Air Quality Standard will reduce “good” air days – Pima County News.