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Jody Harrison of Stone Mountain has known for several years that when the air is so thick it's hard to breathe, she's better off walking on her treadmill indoors, or not exercising at all.
"It took me awhile to get the connection. . . . It's air-related," said Harrison, a trim woman in her 50s. "You can only work out a short amount of time, and your recovery time is longer."
For Harrison, the bad air isn't just inconvenient. It's potentially life-threatening.
Seven years ago, soon after her 50th birthday, she had an emergency heart bypass. Last year, an electronic device called an implantable cardiac defibrillator was installed in her chest to deliver an electric shock if her heart starts beating abnormally fast. The device can prevent a heart attack.
She keeps an eye out for smog alerts because breathing polluted air can raise her heart rate to dangerous levels.
In the past, today --- the last day in September --- would be the last time Harrison could find an air quality forecast until May. Previous smog forecasts have measured ground-level ozone, a component of smog most likely to form in summer. It's created when sunlight reacts with a toxic combination of tailpipe fumes, smokestack emissions and organic releases from trees.
But now smog forecasters from Georgia Tech and the state Environmental Protection Division will be monitoring metro Atlanta's air for a different type of pollution --- particle smog --- and they'll do it year-round, issuing their first forecast Wednesday. Similar forecasts also will be issued in other cities nationwide.
Particle smog can be more dangerous than ground-level ozone, especially for people like Harrison with heart conditions, public health officials say. It's more commonly called soot, and comes from diesel exhaust, wood-burning fires and coal-burning power plants.
Next year, the U.S. Environmental Protection Agency will use particle smog as a standard for judging compliance with the Clean Air Act. A significant portion of Georgia, including metro Atlanta, Athens, Albany, Augusta, Columbus, Macon and Rome, is likely to fail the new standard and be required to come up with pollution controls for industries and people, possibly including a ban on open burning.
There's still a lot that's not known about particle smog. Michael Chang, an atmospheric scientist at Georgia Tech and a member of the forecasting team, said predicting particle smog will be hit-or-miss at first, just as predictions were in the early days of ground-level ozone forecasts.
Scientists also don't know all the sources of particle smog, or how much of it is attributable to power plants vs. diesel trucks. They also don't yet know which types of soot are most harmful.
The tiny carbon and sulfate fragments, which can come from such seemingly benign sources as cars driving on dirt roads and wood-burning fireplaces, are about one-twentieth the size of a human hair. They're small enough to lodge deep in the lungs and work their way into the bloodstream.
Also, based on past monitoring, Chang expects particle smog warning days to be issued about a third as often as ground-level ozone warnings. Metro Atlanta averages about 35 red or orange alert days for ozone levels between May and September; Chang expects about 10 such alerts for particle smog year-round.
And unlike ozone, public health experts aren't sure what people are supposed to do when there's an alert for particle pollution. It took them several years to refine the message for ground-level ozone, warning people to limit their outdoor activities to the morning and late evenings.
But with particles, going inside doesn't help. Eighty percent to 90 percent of the particle pollution outside also can be found inside. In addition, because the particles stay suspended in the air for so long, they pose a threat 24 hours a day.
Right now, the best advice the EPA and public health officials can give is for people with weak hearts or lung disease, as well as the elderly and children, to avoid strenuous activity on a particle smog alert day, designated by orange and red warnings. People breathe in two to three times the amount of air exercising than they do at rest; abstaining from exercise reduces exposure to the particles.
Dr. Howard Frumkin, an environmental health specialist working with the Clean Air Campaign to devise the public health messages for smog alert days, said scientists began learning of particulates half a century ago. That was about the time, in 1952, when thousands of people in London died within a week of heart and respiratory problems. The deaths were linked to a killer smog created by fog and black smoke from coal-burning heaters and fireplaces.
"Epidemiological studies have shown that much lower levels of particulates are also threatening to life," said Frumkin, chairman of the department of environmental and occupational health at Emory University's Rollins School of Public Health. "It was a controversial finding for a long time. It was hard to understand how particulates can actually kill you."
The Natural Resources Defense Council, a national environmental action group, estimated in 1996 that 946 people die prematurely every year in metro Atlanta, and 64,000 nationwide, from cardiopulmonary disease linked to particle smog.
There's some dispute over the finding, including charges that it's overly simplistic because it fails to consider diet and exercise habits. But Frumkin said the report never has been refuted.
Metro Atlanta should get better data soon. Paige Tolbert, an epidemiologist at the Rollins School, is leading an investigative team looking closely at what is in metro Atlanta's smog and what effects it may have on the heart and lungs. Thirty-one metro Atlanta hospitals are participating in the research.
"We're looking at fluctuations of daily measurements in relation to the daily number of [emergency room] visits," Tolbert said. She said the research is showing increased cardiopulmonary problems as metro Atlanta's particle pollution rises.
Copyright 2003 The Atlanta Journal-Constitution
