It's happened several times to both Dani Chapman, 17, an Harriett Owens, 69. A casual trip outside from their homes in Dundalk to a shopping mall or other destination brought on attacks of gasping for breath and wheezing so severe and prolonged that they were rushed by ambulance to a hospital where they remained for a week.
"In summertime, it's hard for me to go out at all," said Ms. Chapman, who is bothered enough by pollution and by certain odors, even perfume, that she has stopped going to school and is studying at home with a tutor. "The air's just like so thick. It usually triggers an [asthma] attack. . . . I've had emergencies a lot. I can't pull myself out of them."
Summertime air pollution or sitting in traffic breathing exhaust fumes can be real dangers for people like Ms. Chapman and Mrs. Owens, who have chronic lung problems.
And research is showing that many healthy people who are working or playing outdoors on a day when urban smog (ground-level ozone) is bad can have lung irritation or decreased ability of the lungs to take in air.
Baltimore is the fourth-worst metropolitan area in the nation for levels of ground-level ozone higher than are allowed by the Environmental Protection Agency, according to latest revised EPA figures. Baltimore ranks behind Los Angeles, Houston and New York, according to the Philadelphia regional office of the EPA.
Summer may be a season away, but reckoning with Baltimore's smog problem is going on right now in the General Assembly, where state environmental officials are pushing for passage of two bills aimed at reducing the major components of smog.
Ozone forms when volatile organic compounds and nitrogen oxide emissions from automobiles and other sources are heated by sunlight.
Last week, the EPA released its annual urban air quality trends report. It said that progress had been made nationally during the 1980s in reducing major air pollutants, including smog, and that the Clean Air Act amendments of 1990 provide the tools to continue improving air quality.
But George P. Ferreri, director of the state Air Management Administration, says Maryland shouldn't be satisfied with abiding the requirements of the Clean Air Act.
He is urging the legislature to pass stricter auto tailpipe emissions modeled on the California motor vehicle emissions certification program. By the year 2007, he said, 50 tons a day of organic compounds will be emitted from Maryland's automobiles under the Clean Air Act requirements, but only 33 tons a day if lTC the California program is adopted here by 1995. That would be a 34 percent reduction of the smog-forming chemical under the Clean Air Act vs. a 58 percent reduction under the California law, he said.
Any reduction would suit Mrs. Owens. "Air pollution and backup from cars affects my breathing. I get very, very short of breath, start wheezing," she said.
The big question science has yet to answer is whether long-term exposure to smog can cause permanent lung damage in people. Evidence has grown in the last few years that ozone causes assorted types of damage to lungs, based on a variety of studies involving human volunteers exposed to varying levels of ozone and from studies of tissue taken from lungs of monkeys exposed to ozone.
Research has shown that damage is reversed soon after the study volunteer is taken away from high levels of ozone, say Robert B. Devlin, an EPA biochemist measuring lung inflammation in human volunteers, and Larry Folinsbee, an EPA physiologist measuring changes in lung function.
The first large study -- of lung tissue from Los Angeles County residents who died in accidents -- is under way to try to answer the questions surrounding longtime exposure.
Dr. Russell Sherwin, professor of pathology at University of Southern California School of Medicine in Los Angeles, said in an interview Friday that he believes this research, together with other studies of ozone effects on monkeys and with human volunteers, shows that ozone can damage lungs. "All data coming together show that ozone is damaging the lung. The problem is I don't know if that is a little bit or a lot," the pathologist said.
In the first 107 cases in the L.A. study -- of people who died between age 14 and 25 -- Dr. Sherwin found that 80 percent had some inflammation of the lungs, 53 percent had mild to moderate inflammation and 27 percent had "severe and irreversible lesions" in their lungs.
"I would expect a high percentage of those people [with severe lung damage] to run out of lung by the age of 50," Dr. Sherwin said.
Even if the L.A. residents didn't develop lung disease, they might have gone on to develop another major health problem later, such as heart disease, because their lungs were not functioning well, he said.
In the 80 percent that had inflammation, the damage occurred where the large airway that brings air into the lungs meets the smaller branches of airways that perform the breathing for the lung, a juncture that seems most vulnerable to such toxic substances as ozone.
Future studies are needed to pin down the role ozone alone plays in causing lung damage and whether the damage can be permanent.