Hoping to pull answers out of air

Scientists look to skies in the city to find causes for rising asthma cases

May 01, 2002|By Tom Pelton | Tom Pelton,SUN STAFF

On a rooftop overlooking Baltimore's Inner Harbor, a robotic arm holding a pair of tubes unfolds and rotates, humming as it sweeps the sky and aims directly at the sun.

Dr. Carol J. Blaisdell and Elissa R. Levine crouch on the roof of the Maryland Science Center like gunners adjusting a weapon in a science-fiction movie.

The two scientists are aiming to understand a mystery. As part of a NASA project, they are studying whether something in the air might be to blame for an almost doubling of asthma cases worldwide over two decades.

The skies over Baltimore are a good place to look for trouble. The city's rate of hospitalizations for asthma is more than twice the rate for the rest of the United States.

A report today by the American Lung Association says that the Baltimore-Washington region has the 11th worst ozone pollution among metropolitan areas in the United States. An earlier study found that Baltimore had the second-highest rate of hospitalizations for smog-related breathing problems in the nation, after Los Angeles.

Twenty-two people, including two children and a teen-ager, died in the city in 2000 because of asthma, according to the latest state figures available. About 8,000 children, 10 percent of the city's school population, miss a day or more of school each year with asthma attacks.

The disease afflicts some 100 million people worldwide, and kills more than 5,000 each year in the United States, although recent statistics suggest that the steep rise during the 1980s and the early and mid-1990s might be leveling off.

Blaisdell, chief of pediatric pulmonology at the University of Maryland, and Levine, a NASA soil scientist, are using their gunlike instrument to count the number of microscopic particles hovering in the air over the city. Particulate pollution has been tied to respiratory ailments and higher death rates.

The device, called a sun photometer, will beam the measurements of particulate pollution into space. The data will bounce off a satellite to a NASA computer center in Virginia, then stream to the NASA Goddard Space Flight Center in Greenbelt.

The researchers will compare asthma-related emergency room visits in Baltimore to ozone and particulate levels, temperature readings, pollen counts, and more than 100 other factors to try to find explanations for peaks and valleys in the frequency of asthma attacks.

As part of the survey, satellites also are snapping pictures of the city from space to measure pollution and foliage.

The $500,000, federally funded project, which will continue for another year, promises to be one of the most comprehensive asthma studies ever attempted.

But the preliminary data suggest a paradox: Hospitalizations for asthma attacks among children in the city are at their lowest during the summer, when ozone levels are highest. This is puzzling because high ozone levels typically are thought to aggravate the lungs of asthmatics.

The scientists are trying to understand why emergency-room visits for asthma quadruple in the fall, when ozone levels drop and children return to school and start spending more time indoors.

For example, from July through September, about 10 children a week are hospitalized in the city for asthma - the lowest rate of the year. In September, the numbers surge to about 40 asthma hospitalizations a week, and they remain high through late November, according to Blaisdell's figures. In winter and spring, about 20 children are hospitalized each week.

At first glance, these numbers seem to conflict with a study published in February by Dr. Rob McConnell, an associate professor at the University of Southern California. He concluded that children who play outdoors in areas with high ozone levels are much more likely to develop asthma than youngsters in areas with low ozone levels.

"You have two studies here that seem to contradict one another - they both can't be right," said Dr. Alan Leff, a University of Chicago asthma researcher.

But Blaisdell says it's too early to reach conclusions about her data because her research is not finished. Asthma is a complex and little-understood disease, and likely has multiple causes that include indoor, outdoor and genetic factors, she said.

"If you had only an ozone hypothesis for the cause of asthma, then one could make the false assumption that ozone is, in fact, inversely related to asthma, and that it could even protect people from asthma," said Blaisdell. "The problem is too complex to have an easy explanation."

One possible reason for the rise in asthma attacks in the fall is that children return to school and pick up viral infections that aggravate their asthma, said McConnell. Others believe that time spent indoors in homes that contain high levels of allergens such as cockroach parts, mouse urine and dust could provoke wheezing.

The Baltimore researchers also are examining demographic data. They want to know whether asthma is more common in poor or industrial neighborhoods than in greener or wealthier neighborhoods.

One might assume that asthma would be worse among people who live near factories or in slums, but sometimes the opposite is true. A German researcher named Dr. Erika von Mutius has concluded that excessive cleanliness might be a cause of asthma. Von Mutius' "hygiene hypothesis" asserts that children who grow up in antiseptic environments might be more susceptible to asthma because their lungs are not used to dirt and irritants.

Because of the conflicting theories, Levine and Blaisdell say they need to analyze as many factors as possible.

"Baltimore has one of the highest levels of asthma in the country," said Levine. "So there is clearly a serious problem here that we need to look into."

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