What you can''t see may hurt you. A study of 20 of America''s largest cities has linked exposure to common pollutants from cars and factories to an increased risk of death.
The study, published in the Dec. 14 issue of The New England Journal of Medicine, suggests that more polluted a city is, the more likely its residents are to die from disease.
Specifically, every time the level of particulate matter smaller than 10 micrometers in diameter increased by 10 micrograms per cubic meter in large cities like New York and Atlanta, there was a 0.51 percent increased risk of death from all causes.
Cardiopulmonary mortality rates, or death from heart or lung disease, were 0.68 percent higher for each 10 microgram per cubic meter increase, said the study.
Researchers took pollution measurements in large metropolitan areas in all regions of the country and then tried to correlate the samples with daily death rates in each of the cities.
They picked so-called "small particle" pollutants, including ozone, carbon monoxide, sulfur dioxide and nitrogen dioxide, since those are thought to be the most dangerous to humans.
Other studies have placed the increased death risk from pollution as high as one percent.
The investigators tried to account for confounding factors that could blur the study''s results.
For instance, they controlled for some measures of socioeconomic status, since it is likely that poorer people, who tend to also have poorer health, live in areas with more polluting cars and factories.
The investigators also believed that it is also possible that people who live in high-traffic cities have higher death rates due to traffic accident and not necessarily pollution.
Still, the authors concluded that so-called "small particle" pollution, like the kind studied here, needs to be strongly limited through EPA.
An EPA regulation to strengthen pollution limits is currently under review by the Supreme Court, with a decision expected this spring.
by Virginia Sutcliffe