This story was originally published by the Guardian and is shared here as part of the Climate Desk collaboration. An increasing number of Americans live in places with unhealthy levels of smog or particulate air pollution—both of which are being made worse by climate change, according to a new report. Air quality in the US has been improving since the 1970s, but that progress may be backsliding and 43 percent of Americans are now living in places where they are breathing unsafe air, according to the American Lung Association report. As temperatures rise, wildfires are getting worse and spewing smoke across the west.