More than 166 million people in the U.S.—52 percent of all Americans—are exposed to unhealthy levels of either ozone or particulate pollution, putting them at risk for premature death and other serious health effects, including lung cancer, asthma attacks and developmental harm, according to a report published Wednesday by the American Lung Association.
Despite lower ozone levels and long-term averages of particulates, the annual State of the Air report suggests global warming is causing short-term spikes in air pollution. The spikes result from droughts and wildfires that temporarily increase particulate levels from dust and smoke. Wildfires occur more frequently and with greater severity in drier, hotter climates affected by global warming.
Seven of the 25 most polluted cities in this year's report had their highest number of unhealthy short-term particle pollution days ever reported.