Air pollution in American cities has accounted for an estimated 60,000 deaths a year, making it among the nation's top killers, according to researchers.
The risk of death is greatest among the elderly and people with lung and heart disease, said Joel Schwartz of the Environmental Protection Agency, who worked with another researcher on the air pollution study released yesterday in Anaheim, Calif.
The study focused on particulates, or tiny airborne particles.
"There hasn't been much attention focused on particulates, and the standards are fairly loose," Schwartz said, after presenting the findings at the 1991 International Conference of the American Lung Association in Anaheim.
"It comes out of electric power plants. It comes out of diesel trucks," Schwartz said. Factories, smoke, aerosols, dust and naturally occurring microorganisms are also to blame for airborne particles, he said.
The estimated 60,000 deaths a year account for 3 percent of all deaths nationwide, Schwartz said.
Those deaths linked to air pollution during the study occurred at levels of airborne particles below the standards set by the federal government, he said.
Schwartz said he expects the study's findings to push federal officials to change regulations. "Eventually, it will result in a tighter standard, but not next year," he said.
The study found that the number of deaths rose by 7 percent when the level of particles increase 100 micrograms per cubic meter, he said. The death rate increased by 5 percent for 100-microgram increase in sulfur dioxide, Schwartz said.
For people older than 65, the impact of particles in the air was three times greater than for people younger than 65, Schwartz said.
For people with asthma, bronchitis or chronic obstructive lung disease, the death rate was 20 percent greater for increases of 100 microgram per cubic meter, he said.
Schwartz said people should stay indoors when the pollution levels are high because that will filter out about two-thirds of the particles.
Philadelphia was chosen as a site for the study because it is typical of a large American city and one of the few that measure particle pollution levels daily, Schwartz said.
Schwartz conducted the report with Douglas Dockery, associate professor of environmental epidemiology at the Harvard School of Public Health.