Microscopic particles of air pollution, largely from diesel and gasoline exhaust, cause an estimated 275 premature deaths from heart and lung ailments yearly in Riverside and San Bernardino counties, according to a new study by state health experts.
Although research in other industrialized U.S. cities has linked early deaths to particulate pollution, the study is the first to focus on California.
The deaths, representing a 2% increase in mortality in the two inland counties, was based on summertime pollution levels between 1980 and 1986 in western San Bernardino County, which experiences some of the highest concentrations in the nation. Lower but similar levels of particulate pollution are found throughout the Los Angeles region.
"These findings are not unique to these two counties," said Bart Ostro, who wrote the report and is chief of the California Environmental Protection Agency's air pollution epidemiology unit. "We also see a very similar association" in other areas.
The ultra-fine pieces, which vary in content from carbon soot and nitrates to road dust, measure under 2.5 microns--a fraction of the diameter of a human hair--and seem to lodge in the lungs and aggravate heart conditions.
The study bolsters an effort by the South Coast Air Quality Management District and the state to develop a strategy by February, 1997, for reducing the airborne particles as required under federal law. The pollution-fighting techniques, however, are highly contentious since control of diesel trucks and other heavy-duty equipment is expensive and technically difficult.
Ostro said particulate pollution is not just causing deaths among terminally ill people. He said it could be shaving many productive years off the lives of those who would otherwise live longer. Children and adults with heart and lung ailments may be the most vulnerable, but more research is needed to determine who faces the highest risk, he said.
"The impact is probably not uniform across the population, but we haven't yet sorted that out," said Patrick Kinney, a Columbia University School of Public Health researcher. "We do know older and sicker people are more impacted by air pollution."
Another, much larger study unveiled last week by a team of health experts concluded that particulates in 151 U.S. areas, including the Los Angeles Basin, reduce average life expectancy by one to three years. In 1993, a smaller study of six cities conducted by the same researchers determined that the particles increase the risk of early death by 26%.
Brigham Young University epidemiologist C. Arden Pope III, an author of the nationwide study, on Friday called the findings released last week reassuring because they mean experts have identified a major contributor to deaths associated with heart and lung problems.
"We have found a preventable cause of mortality," he said.
Pope said the evidence linking particulates to the risk of early deaths is very persuasive because it has been found "across different researchers, study areas and study designs" over the past decade.