An international team of researchers used data from 652 cities in 24 countries to correlate levels of particulate matter pollution with day-to-day mortality rates.
They measured the concentrations of two microscopic particles of soot, PM 2.5 and PM 10, particles small enough to enter the lungs or the bloodstream.
The study, in the New England Journal of Medicine, found that as the concentration of particulate matter increased, so did the number of excess deaths.
In the United States, there was a daily mortality increase of 0.79 percent for each 10 micrograms per cubic meter increase in PM 10 and a 1.58 percent increase for each 10 microgram increase in PM 2.5. This would translate to an extra 178 deaths on a day when levels of these pollutants increased by these amounts.
The Environmental Protection Agency sets a three-year daily average of 12 micrograms of PM 2.5 and 15 micrograms of PM 10 as the limit for protection of public health.
“Lowering the present U.S. limits could reduce the number of deaths,” said a co-author, Antonio Gasparrini, of the London School of Hygiene and Tropical Medicine. “But there’s a tradeoff — how much you can realistically do against how many lives you can spare. We’ve provided the level of risk. Policymakers have to work with it.”[Source]