The association said nearly 400 counties failed. Kay Prince, chief of the air planning branch at EPA's regional office in Atlanta, hadn't seen the rankings, but attested to the trend. You put it all together and you get some increased values. Ozone is a form of oxygen formed when sunlight reacts with pollutants such as those from tailpipes and industries. Inhaled at high concentrations, it is a powerful irritant that can cause shortness of breath, chest pain and wheezing.
Regular exposure can reduce how well lungs work.
All have done so, though some are awaiting final approval. North Carolina is expanding its program to about half its counties. Overall U.S. ozone concentrations dropped 16 percent between 1988 and 1997, the lung association said. Whenever alerts are issued by government agencies that the air is unhealthy, experts say adjust your plans. Avoid prolonged outdoor exercise if ozone levels are high, and save the most strenuous activities for early morning hours.