Day-to-day increases in air pollution, even at levels generally considered acceptable, are associated with increased deaths among the elderly.
Previous studies have suggested an association, but most have been based on small populations in metropolitan areas. This new study, in JAMA, used Medicare files and nationwide air pollution data to estimate 24-hour exposure in people who died between 2000 and 2012.
The researchers found that for each day-to-day increase of 10 micrograms per square meter in fine pariculate matter (PM 2.5), the small particles of soot that easily enter the lungs and bloodstream, there was a 1.05 percent increase in deaths. For each 10 parts per billion increase in ozone, a main component of smog, there was a 0.51 percent increase.
The effect was greater for low-income people, African-Americans, women and those over 70, and the risk remained significant even at levels below what the Environmental Protection Agency considers safe.
“This translates to PM 2.5 causing an extra 20,000 deaths a year,” said a co-author, Joel D. Schwartz, a professor of epidemiology at Harvard. “Separately, a 10 parts per billion decrease in ozone would save 10,000 lives per year.”
This amounts to more deaths per year than caused by AIDS, Dr. Schwartz said. “But unlike AIDS, we know the cure: scrubbers on coal-burning power plants that don’t have them, and reduction in nitrogen oxide emissions because they drive the production of ozone.”