EPA: Pima County air quality below standards for four years

The Associated Press

Under new, more stringent Environmental Protection Agency air quality standards, Pima County’s air would have exceeded ozone levels from 2003 to 2007.

The new standard allows .075 parts per million of ozone for healthy air, down from the current level that ranged from 0.08 to 0.084 ppm for more than a decade.

Results from one of eastern Pima County’s nine air quality monitoring stations would have violated the healthy standard under the new limits, said Beth Gorman, program manager at the Pima County Department of Environmental Quality.

Using air quality records and a complex formula, it was determined that Saguaro National Park Rincon Mountain District east of Tucson would have exceeded the new standard each year from 2003 through 2007, she said.

During warm summer months, prevailing afternoon eastern winds blow pollutants, primarily from vehicles, toward Saguaro National Park Rincon Mountain District, where the sun’s heat converts them into ozone in a complex chemical process, Gorman said.

Ozone can harm the health of people with lung problems, the elderly and the young. It forms when nitrogen oxides and volatile organic compounds are heated by the sun.

Ozone is the primary component of smog, according to the EPA. Summer afternoons are typically when the area sees high ozone levels, Gorman said.

Other sites came close to noncompliance in the past based on the new standard but did not exceed it, she said. The last time Pima County exceeded EPA’s healthy ozone standard was 1983, when the standard was more lax, Gorman said.

To combat out of control ozone levels, air quality managers suggest driving less, keeping vehicles well maintained and tuned, keeping tires properly inflated and refueling late in the day when the sun is going down.