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PRI's Environmental News Magazine

Deadly Particulates

Air Date: Week of

Living on Earth's Kim Motylewski reports on the latest study linking particulate air pollution — microscopic airborne grit — to higher death rates, even at levels the EPA calls safe. Scientists say that particulates cause up to sixty thousand premature deaths each year in the United States.


CURWOOD: This is Living on Earth. I'm Steve Curwood.

Air pollution is generally bad for our health, and increasingly, researchers are saying fine little particles are the most lethal form of air pollution. Much of this microscopic grit comes from vehicles, especially diesel engines, and from power plants and factories, especially those burning coal. People in cities are most at risk, but even country dwellers can't escape. Wood burning stoves, crop burning and dusty roads also generate worrisome particulates. The US Environmental Protection Agency is required to set limits on particulate pollution to protect public health. But scientific studies are calling the current EPA standards into question. They suggest that officially safe air is in fact causing serious health problems, and as many as 60,000 premature deaths a year in the US. Living on Earth's Kim Motylewski has our story:

MOTYLEWSKI: Outside the mall in Watertown, Massachusetts, shoppers instinctively cover their noses as a bus pulls away from the curb. They try to keep from breathing the gritty exhaust from its diesel engine. Exhaust from buses like this one is regulated under US clean air laws, and the EPA says the levels of particulate pollution in the air of this small city outside Boston are safe. But a study of the air in Watertown and five other cities, just published in the New England Journal of Medicine, shows that particulate levels which are considered safe are significantly shortening people's lives. The study by researchers at the Harvard School of Public Health is the latest of several documenting the health effects of the microscopic grit collectively known as particulates. Particulates come not only from diesel engines, but also from power plants, wood stoves, industrial coke ovens, mining, and construction operations. They've been linked with a whole host of health problems and higher mortality rates. Previous studies have suggested that if the air in the United States was perfectly particulate-free, each year 60,000 fewer people would die. The new study is noteworthy because it followed 8,000 people in six cities for 14 years, and controlled for cigarette smoking and other risk factors. It correlated death rates with particulate levels and other types of air pollution, and it found that certain particles were consistently the most important. Overall, the city with the most particle pollution in the sample had about a 25% higher death rate than the cleanest city. Douglas Dockery is the epidemiologist from Harvard who led the research team.

DOCKERY: Let me express it this way. The effect would be to reduce the average life span in the more polluted cities by one to two years.

MOTYLEWSKI: Dockery says none of the particulate levels they studied was safe.

DOCKERY: One of the striking findings here was that we could observe increased mortality across the full range of exposures. Any small increase in particle exposures across these six communities was associated with a small but detectable increase in mortality.

MOTYLEWSKI: These new findings add to the growing pressure on the EPA to review its particulate standards. John Bachman of the EPA's Air Quality office says that if the agency verifies these findings, a stricter standard is likely.

BACHMAN: I think it would be premature to say that while it's all new information, it's correct, there's no question about it, and therefore the current standards are wholly inadequate. On the other hand, it's important to take cognizance of the new information. It strongly suggests that the standards may not be adequate in terms of protecting public health.

MOTYLEWSKI: Bachman says a review of particulate standards will take at least five years. For Living on Earth, I'm Kim Motylewski.



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