Smoke from wildfires burning across the American West causes greater health damage east of the Rockies than to their west, a new study shows. About three-quarters of deaths and asthma visits to emergency departments related to smoke over the past decade have occurred in the East because of higher population densities. “Smoke is not just a western problem,” Katelyn O’Dell, lead author of the study, told the Washington Post. Wildfire smoke includes numerous pollutants, and the scientists looked specifically at the harms caused by fine particulate matter, known as PM2.5, which gets deep into lungs and worsens and leads to myriad health problems. The research underlines the widespread harms caused by wildfires, which are made worse by human-caused climate change, despite their localized acute destruction. (Washington Post $, CNN; Climate Signals background: Wildfires)