Hazy summer days boost respiratory ailments.

The number of people hospitalized for various respiratory ailments in New York State's largest urban centers increases significantly on days when summer's skyscraper-obscuring haze of air pollution hangs thickest, a new study finds.

Public health researchers have attempted to show links between air pollution and hospital admissions for various respiratory problems, especially asthma attacks (SN: 5/6/89, p.277; 4/6/91, p.212). A 1987 study conducted in Ontario, Canada, for example, indirectly linked concentrations of acid aerosols - fine, caustic droplets that form from gases emitted by coal-fired electric power plants and other industrial sources --with the incidence of respiratory illnesses.

In the new study, George D. Thurston of the New York University Medical Center's Department of Environmental Medicine in Tuxedo, N.Y., and his colleagues measured acid aerosols directly for the first time, then associated this form of air pollution with hospital admissions for a variety of respiratory illnesses.

Examining a population twice as large as the one covered in the Ontario study. Thurston explains, the researchers gathered statistics on people with acute respiratory complaints admitted to 139 hospitals in New York City, Albany, and the Buffalo-Rochester area during the summer months of 1988 and 1989. These patients suffered from asthma attacks, bronchitis, pneumonia, and other acute conditions. For the same period, the researchers tracked daily concentrations of acid aerosols and ground-level ozone, which originates chiefly from automobile emissions.

Thurston's team discovered a statistical correlation between acute respiratory problems and increased concentrations of pollutants in the summer haze that blankets New York's urban centers each year. On the worst ozone days, for example, admissions for asthma increased 23 percent in New York City and 29 percent in Buffalo, the researchers report in the just-released October-December JOURNAL OF EXPOSURE ANALYSIS AND ENVIRONMENTAL EPIDEMIOLOGY.

The study also suggests that acid aerosols worsen the effects of ozone on the sensitive tissues lining the airways. Although this relationship needs further investigation, "it makes sense that if you have acid around, it's going to irritate the lung lining and open it up to ozone's effects," Thurston explains.

The researchers also found that residents of urban centers suffer more often from air pollution's ill effects than people who live in suburbs, despite nearly identical exposures to ozone and acid aerosols. Since inner-city areas have the highest percentage of New York's disadvantaged population, poor nutrition or inadequate health care may play a role in these disparities, the report suggests.

Environmental epidemiologist Douglas W. Dockery of the Harvard School of Public Health in Boston cautions that the statistical links in Thurston's study are not strong enough to prove definitively that such pollutants trigger asthma attacks or cause other respiratory conditions. "But this study is important because it's one of the first to have direct measurement of acid aerosols, and there's been a lot of laboratory work suggesting that acid aerosols might be the most important air pollutant in the summer haze," he says.