air pollution

Even Low Air Pollution Exposure Increases Death Risk in Elderly

Short-term exposure to air pollution levels below current air quality standards may increase the risk of death among older adults, according to the results of a recent study.

Every 5 years, the US Environmental Protection Agency is required to reexamine the National Ambient Air Quality Standards.
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In order to estimate the association between short-term exposure to ambient fine particulate matter (PM2.5) and ozone, researchers conducted a case-crossover study and conditional logistic regression. Daily PM2.5 and ozone levels were estimated in the entire Medicare population residing in39,182 zip codes from January 2000 to December 2012.

Overall, there were 22,433,862 case days and 76,143,209 control days, with 93.6% having PM2.5 levels below 25 μg/m3, during which time 95.2% of deaths occurred. Further, 91.1% had ozone levels below 60 parts per billion, during which 93.4% of deaths occurred.

The baseline daily mortality rates were 137.33 and 129.44 for the year and for the warm season, respectively. Every short-term increase of 10 μg/m3 in PM2.5 and 10 parts per billion (10−9) in warm-season ozone were significantly associated with a relative increase in daily mortality rates of 1.05% and 0.51%, respectively.

“In the US Medicare population from 2000 to 2012, short-term exposures to PM2.5 and warm-season ozone were significantly associated with increased risk of mortality. This risk occurred at levels below current national air quality standards, suggesting that these standards may need to be reevaluated.”

—Michael Potts

Reference:

Di Q, Dai L, Wang Y, et al. Association of short-term exposure to air pollution with mortality in older adults. JAMA. 2017;318(24):2446-2456.