Senator Eliot Shapleigh - El Paso, Texas

After Beth Lutz returned to Denton from a California vacation, her eyes began itching and burning again. Her throat is always irritated, too.

"I don't know what's in the air here," Lutz said.

According to state and federal data, it's ozone. And greenhouse gases. And other noxious elements.

The American Lung Association gives Denton County air quality an "F," identifying about 37.6 percent of the population – more than 230,000 people – as being most at risk on days with heavy smog.

Children and adults with asthma and other breathing disorders, such as emphysema and chronic bronchitis, struggle to breathe on days when ground-level ozone reaches even moderate levels. People with heart disease and diabetes also are at risk when the air gets bad.

For healthy people, breathing polluted air lowers the body's natural resistance to respiratory infections such as the flu, according to Dr. Norman H. Edelman, the association's chief medical officer.

The Denton Airport's monitoring station has logged 84 bad-air days in 2009. Preliminary data from the Texas Commission on Environmental Quality shows July 2 was the worst day so far, with 91 parts per billion of ozone in the air for eight hours. Seventy-five parts per billion is the standard.

In 2007, TCEQ adopted an improvement plan that was supposed to clean the air and meet a federal deadline of summer 2009 to bring Dallas-Fort Worth into compliance.

Susana Hildebrand, chief engineer with TCEQ, said the vast majority of ozone-making emissions in the Dallas-Fort Worth area come from vehicles, but federal law prohibits the agency from writing statewide rules for cars and trucks.

"The most we could do was adopt California's standards," Hildebrand said.

But they didn't. It was not clear whether TCEQ had the legislative authority to adopt them, she said. In addition, the agency's technical staff believed California's standards weren't different enough from federal guidelines to help, especially by the time they would have been enforceable.

With the plan's failure, the Dallas-Fort Worth area faces more stringent federal controls, which could make it more expensive for businesses to grow and expand, Hildebrand said.

The 2007 plan did not include several key recommendations that could have made a difference, according to Southern Methodist University engineering professor Al Armendariz. He serves on the advisory board for the National Resources Defense Council, a nonprofit group dedicated to environmental issues.

Those rejected measures included stricter standards for vehicle emissions, for power plants in East Texas and concrete plants in Ellis County whose emissions drift into the region, and for Barnett Shale natural gas facilities.

So far this spring and summer, northern Tarrant County and Denton County are racking up bad-air days faster than more populous parts of Dallas-Fort Worth, Armendariz said. Monitoring stations in Keller and at Eagle Mountain Lake already have logged 85 bad-air days, the number that triggers failure. Denton, at 84, is poised to fall next.

Denton Mayor Mark Burroughs served on the North Texas Clean Air Steering Committee, which helped form the 2007 plan. In an interview last week, Burroughs said he was disappointed the state did not adopt all of the committee's recommendations.

"I thought we had a great package," Burroughs said, adding that state officials never explained to rank-and-file committee members why they didn't accept some proposals.

The failure to adopt stricter pollution controls on cement kilns was most puzzling, because industry officials had signed off on the recommendations, said Burroughs, who served on a subcommittee that studied the issue.

Because of wind patterns, Denton residents breathe polluted air from cities to the southeast, including Midlothian, home to several cement plants, Burroughs said.

"It's like an overcrowded bus stopping somewhere and getting more passengers on; it becomes worse and worse and worse," he said.

Burroughs recently devoted an episode of his "Mayor's Minute" television and Internet broadcast to air quality, stressing mass transit, bicycle lanes and other ways to cut air pollution.

"Yes, we are a victim in many ways, but we have to be at the forefront of a solution," he said.

"When you're a victim for years, you have to do something about it. We have to show others that we're willing to do it whether we caused the problem or not."

Some of Denton's problems are homegrown.

The mining, refining and compression of Barnett Shale natural gas contributes as much pollution as all the region's cars, trucks and airplanes, according to both the TCEQ and Armendariz, who studied the problem earlier this year.

Energy companies often get air permits for individual components – separators, compression engines and tank batteries – as they are built, attesting in their applications that even though Denton County is a noncompliant area, their pollution is a minor source of volatile organic compounds.

In Dish, where 10 high-pressure natural gas pipelines converge in a Grand Central Terminal-like industrial zone, Mayor Calvin Tillman questions the state's practice of not considering the whole area when evaluating components for their pollution potential.

The Dish area is on TCEQ's radar, Hildebrand said, adding that she has already talked with the commission's executive director about taking some measurements in the area.

"We can do some mobile monitoring in that area to see what concentrations there are," Hildebrand said.

Meanwhile, TCEQ officials have been collecting infrared video of gas well sites and production facilities to identify potential trouble spots. Most of those emissions are more likely to be volatile organic compounds than nitrogen oxides.

"If you reduce [nitrogen oxides], you'll reduce ozone," Hildebrand said. "Having said that, we're just as concerned about emissions of those other compounds."

The Texas Commission on Environmental Quality takes ambient air readings of ground-level ozone at 21 monitoring stations around the region. Those readings become part of the data for an Environmental Protection Agency standard for air quality. The standard measures a three-year average of ozone concentrations at thresholds the EPA considers a reasonable protection of public health.

Ozone: Ozone gets cooked up at ground level by sunlight – a chemical reaction between volatile organic compounds and nitrogen oxides. Ozone reduces lung function, and repeated exposure can permanently scar the lungs.

Volatile organic compounds: Lesser players in the ozone problem than the nitrogen oxides, but a greater problem for indoor air quality. These carbon compounds have varying effects – from none at all to carcinogenic and highly toxic – depending on the compound and the concentration.

Greenhouse gases: Four major players in the ozone problem – carbon dioxide, methane, nitrous oxide and fluorinated gases – trap heat in the atmosphere. All have increased with industrial development, with fluorinated gases being entirely a human invention.

Toxic releases: If released into the air, these chemicals – such as lead and lead compounds – are known to travel far from their source and settle on the ground into long half-lives that present great risk to human health. They are often sorted as carcinogenic and noncarcinogenic agents. Among the noncarcinogenic agents are chemicals that can compromise human growth and development, immunity, or the respiratory and neurological systems. Amounts released are self-reported to the EPA – "an honor system" of reporting by those who release the toxics.

SOURCES: Environmental Protection Agency; Texas Commission on Environmental Quality