After years of teetering on the edge of federal ozone standards, San Antonio has joined the ranks of Houston and Dallas in violating the Environmental Protection Agency standard for clean air.

On Tuesday, ozone readings at Camp Bullis and Marshall High School in the north of the county were at 76 parts per billion, just over the EPA limit of 75 ppb.

Increased air pollution from the oil and gas boom of the Eagle Ford Shale is believed to be a factor, in addition to local sources and pollution coming from Mexico, East Texas and the East Coast.

Until now, Bexar and surrounding counties took pride in being the largest metropolitan area in the country that was below the standard.

“It is my great and genuine regret to say that we are now showing readings in violation” of the 2008 eight-hour standard for ground-level ozone, said Peter Bella, natural resources director at the Alamo Area Council of Governments.

Ground-level ozone, even at low levels, can cause health effects, especially for those with lung disease, and in children, older adults and people who are active outdoors.

“This new status means that what we are finally doing is acknowledging the problem,” said Janice Nolen, assistant vice president of national policy and advocacy for the American Lung Association.

Ozone is created when emissions from industrial facilities, electric utilities, vehicle exhaust, gasoline vapors and chemical solvents are baked in sunlight.

The Camp Bullis and Marshall monitoring stations tend to see the highest readings because they are downwind from the pollution sources in San Antonio. The monitors, plus one at Calaveras Lake, in southeastern Bexar County, are used to extrapolate air quality for the 12 counties included in AACOG.

Besides being a plus for public health, being in attainment meant San Antonio did not have to require emission testing of vehicles. It also did not have the threat of federal dollars for highway projects being limited.

Now San Antonio and the surrounding counties will need to focus their efforts to reduce pollution to prove to the EPA the standard is being taken seriously, Bella explained. Otherwise, the EPA could add the area to the nonattainment list.

“I think this violation at best represents a warning that we need to be very vigilant while it remains a voluntary basis,” he said.

AACOG is looking at ways to reduce pollution. Suggestions include limiting the hours construction sites can use generators, encouraging drivers not to let their car engines idle when they're stuck in traffic and the use of public transportation.

Being on the nonattainment list mandates the region develop a plan to reduce pollution, but the likelihood of being listed is low for now, since the data has not been verified and the EPA will be considering new limits next year, agency spokesman Dave Barry said.

“It's at our discretion,” he said. “What (EPA) is doing is encouraging cities such as San Antonio to participate in the Ozone Advance program, which helps them either stay in compliance or bring them back into standard.”

San Antonio was accepted into the program in July. The program will help it qualify for grants and make it easier to work with the federal government to reduce emissions.

This relationship could prove to be critical because the EPA will review the current ozone standard in 2013.

The 75 ppb standard was set in 2008. Last year, the EPA announced it was considering a new standard of between 60 ppb and 70 ppb but then did not act after hosting public meetings, Barry said.

On Tuesday, a federal appeals court overturned an Obama administration rule that would have limited pollution for power plants and the amount of pollution that could cross state lines.

“Because there will be a delay in cross-state air emission (limits), we won't see reductions in cross-state pollution that we had anticipated,” said Elena Craft, a health scientist at Environmental Defense Fund.

Bexar County Judge Nelson Wolff, vice chairman of

AACOG's air-improvement resources committee, explained that other than the steps being taken by CPS Energy — voluntarily closing its dirtiest coal power plant, investing in renewable energy and encouraging conservation — the region has few options to reduce pollution because it can't control what is brought in by the wind.

“Public transit and living closer together are the only things that I know we can make a difference,” he said. “Change the dynamics of all of us driving out farther and farther.”

Because of the anticipated new standards, San Antonio should have several years to meet the limits.

cmcdonald@express-news.net