Intense Heat Begets Intense Smog

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.

“We’ve had some awful, hot weather,” he said, with conditions “some of the worst we’ve seen for the formation of ozone in a number of years.”

But Millett said, “If we’d experienced these same conditions 10 years ago, we would be having much more severe air quality problems.... Ozone pollution concentrations have declined about 20% since 1980” due to regulation of power plants, car fuel and other measures.

He said even if temperatures continued to rise in coming years, new programs to control emissions from diesel trucks and farming equipment, and requiring cleaner diesel fuel would help reduce smog levels further.

He said a new rule to regulate marine vessels and locomotives was expected by year’s end, and added that technological challenges in developing equipment had delayed its implementation.

Sam Atwood, spokesman for the South Coast Air Quality Management District, said the agency needed as much help as possible from the federal government to reach legal smog levels by a 2021 deadline.

He said Crestline often experiences the state’s highest smog levels because it catches ozone from across the Los Angeles Basin as it is blown inland by marine breezes and trapped by the mountains.

Glendora, he said, “is a bit more of a throwback.” He noted that the city had high smog levels in the 1990s, but since fuels had been improved, it usually took longer for fumes to swirl through hot air to form smog -- meaning smog now usually develops farther inland. He said he didn’t know why the city would have had the highest hourly reading last month.

Other major metropolitan areas with high smog days included New York; Philadelphia; Washington; Baltimore; Atlanta; Denver; Dallas; Houston; Salt Lake City; San Diego; Sacramento; St. Louis; New Haven, Conn.; Chattanooga, Tenn.; and Baton Rouge, La.