Los Angeles is the nation's dirtiest city, keeping the spot it has held for a decade now.
"It will likely remain on top of the most-polluted list for ozone for a long time, but they have made improvements," Nolen said.
Other dirty cities for ozone: Bakersfield, Calif.; Visalia-Porterville, Calif.; Pittsburgh-New Castle, Pa.; and Fresno-Madera, Calif.
Eighty million more Americans (175 million) than last year live in areas with unacceptably high smog (ozone) levels too many days of the year, reflecting both a warmer climate as well as new ozone standards.
"Ozone causes inflammation by burning the lining of the airways. It's like getting sunburn in your lungs," said Dr. Norman Edelman, chief medical officer of the lung association. "Ozone pollution can cause premature death, shortness of breath, chest pain when inhaling, wheezing and coughing, asthma attacks, increased susceptibility to lung infection and increased need to receive medical attention for lung diseases like asthma or COPD [chronic obstructive pulmonary disease]."
Even short-term exposure to particulate pollution can be deadly, from lung disease as well as heart attacks and stroke.
New research from California has tripled the number of estimated premature deaths from particulate matter, according to the lung association.
On the other hand, Edelman added, one nationwide study found that the average life expectancy in 51 cities had increased by five months between 1980 and 2000 as a result of air pollution reductions.
To aid the cause, consumers can use less electricity, drive less, avoid burning wood or trash and push for clean-up of old diesel bus fleets in their communities, Connor suggested.
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