July's scorching heat wave created a "blanket of smog" from California to Maine, with the number of unhealthy days up from last year in 38 states, according to data compiled by a watchdog group.
Public health standards for ozone smog were exceeded more than 1,000 times at official air pollution monitors last month, according to Clean Air Watch. The trend could continue this week with record-breaking temperatures in many parts of the country.
"California by far has had the worst air quality. But we are even seeing problems at some unusual places -- a lot in Colorado, some in Washington state and Oregon, even Martha's Vineyard," said Frank O'Donnell, president of Clean Air Watch, which had volunteers review government data.
Southern California once again had the highest smog levels in the nation. The worst single day -- an average of 142 parts per billion -- was July 25 at Crestline in the San Bernardino Mountains. The worst single hour, at 175 ppb, was on July 22 in Glendora.
The federal government has set safe limits at 85 ppb; California has a tougher standard of 70 ppb. Above those levels, senior citizens, infants, asthma sufferers and others can experience serious health problems, according to scientific studies.
"This is not a freak thing. This is a horrifically hot summer ... and it's hazardous to your health," said William Becker, executive director of a national association of local air quality officials. "The conditions for creating smog and unhealthy air are extremely ripe ... and it's vitally important EPA take swift and aggressive actions, including regulating locomotives and marine vessels ... which in the next 10 or 15 years are going to be the predominant source of smog."
Air quality advocates said the heat wave was perfect for producing peak smog levels, and they warned that reductions in smog in past decades could be eroded by global warming.
Ozone is a colorless pollutant formed when heat and sunlight "cook" nitrogen oxide and volatile organic compounds from vehicles and industrial sources.
"Long-term we have made improvements ... but this heat wave and the accompanying smog is a very graphic reminder that we still have a significant problem," O'Donnell said. "Unless we start getting serious about global warming, predicted temperature increases in global temperatures could mean continued smog problems in the future. And that will mean more asthma attacks, disease and death." EPA spokesman John Millett did not dispute the survey findings, although he noted that the group analyzed raw data from government monitors that still needed to be verified.
