Deadly 'Double Whammy:' Heat Wave, Plus Air Pollution

Prolonged heat can increase the risk of a heart attack. So, too, can exposure to air pollution. "The two things together are more than a double whammy," epidemiologist Joel Kaufman of the University of Washington tells the Wall Street Journal, referring to a new study in the journal Circulation. Researchers (Kaufman was not involved in the study) looked at more than 200,000 heart attack deaths in China and found the greatest risk came when extreme heat for several days combined with high pollution levels, reports CNN. Older people and women were the most vulnerable.

Specifically, researchers found that the risk of a fatal heart doubled if a heat wave went on for four days amid air pollution—or fine particulate pollution—measured at above 37.5 micrograms per cubic meter. The odds increased depending on how hot things got, but the uptick began with temperatures in a range of 83 to 98 degrees. The study also found that extreme cold also seemed to increase the risk of heart attacks. "Extreme temperature events are becoming more frequent, longer, and more intense, and their adverse health effects have drawn growing concern," said senior author Yuewei Liu of the School of Public Health at Sun Yat-sen University in Guangzhou, China. (More health study stories.)