Smog in Central Maryland endangers more than 54,000 asthmatic children, mostly in the suburbs, says a report released yesterday that tallied the number of youngsters living in the nation's smoggiest areas.
The American Lung Association said 743,000 children under 14 reside in Maryland's smog corridor -- from the Washington suburbs through the Baltimore metropolitan area into Cecil County -- and even youngsters without asthma face some risk.
"Children's lungs are not just miniature versions of adult lungs," said Dr. Rebecca Bascom, a pulmonary specialist at the University of Maryland Medical Center. "They are especially sensitive to infection and pollution."
Summer is a time for children to frolic in the pool or on the ball field. But the hot hazy days of vacation include an element of risk: pollution that can damage young lungs.
Smog forms when hot summer sun causes hydrocarbons and nitrogen oxides to combine in the air.
Ground-level ozone, the main component of smog, can inflame the lungs and cause shortness of breath, chest pain, wheezing and coughing.
Children's lungs still are developing, so their biological defenses against intruders such as ozone are not fully formed. And children's airways are narrow, worsening the effect of any inflammation.
Using U.S. Census Bureau and health statistics, the lung association calculated that roughly half the nation's children, 27 million, live in regions where ozone sometimes reaches harmful levels.
Concentrations in the Baltimore area, which has the nation's sixth-worst smog problem, exceeded the federal safety standard 11 days last summer, but levels deemed unhealthy by the lung association occurred on 79 days.
The Environmental Protection Agency says it may lower the federal standard because of scientific evidence that repeated or long-term exposure to smog at levels 33 percent below the present limit can impair breathing and cause potentially harmful changes in the lungs.
Lilli Schestag, 11, of Columbia may be typical of the thousands of Baltimore-area children with asthma who must restrict their activities on hot afternoons -- the worst time for ozone pollution. She said she retreats indoors.
Though individuals vary in their sensitivity to ozone, doctors say children are especially vulnerable because they spend more time outdoors than adults and engage in strenuous exercise or play that increases the amount of ozone they inhale.
"Despite air quality improvements in the early 1990s, smog remains a major health threat to America's children," said Dr. Alfred Munzer, past president of the lung association.
He warned that legislation pending in Congress could halt or even reverse the progress made in cleaning the air in Maryland and the rest of the country.
The hazard is more than hypothetical for children with asthma because their airways already are injured and especially sensitive to irritants such as ozone. Research indicates that smog may help trigger the attacks that leave sufferers gasping for breath.
"Pollution per se may not give you an acute asthma attack, but [the inflammation] sets you up," said Dr. Gerald M. Loughlin, director of pediatric respiratory sciences at the Johns Hopkins Medical Institutions.
Lilli Schestag, the 11-year-old from Columbia, knows too well the consequences of playing kickball or tag outside when the temperature -- and smog levels -- are creeping up.
"I get really hot, and my eyes get all itchy. And I sneeze a lot, and I start coughing," she said.
Her mother, Leah Schestag, no longer lets her play outdoors after noon when the temperature reaches the 90s. "After watching her health deteriorate every summer for three years, I wasn't going to do it anymore," said Mrs. Schestag. "By Labor Day every summer, the child was deathly ill with pneumonia."
Now, when summer rolls around, Mrs. Schestag keeps tabs on ozone by telephoning the air-quality hot line maintained by the Maryland Department of the Environment. When ozone nears unhealthful levels, she makes Lilli and her 8-year-old sister stay in their air-conditioned home.
Ozone concentrations in the suburbs often exceed those in downtown Baltimore or Washington, because the pollution -- brewed from the emissions of motor vehicles, power plants and thousands of other small sources -- is transported in a northeasterly direction and dispersed by prevailing winds.
"Ozone continues to be the most pervasive air pollution problem in the United States," said Mary White, an epidemiologist with the U.S. Centers for Disease Control and Prevention in Atlanta, which today is publishing the lung association data.