environment
Wildfires are undoing years of cleaner air in the U. S.
June 5, 2026
For over a decade, the U. S. had been making steady progress in reducing ground-level ozone—a harmful pollutant that damages lungs and triggers breathing problems. Between 2003 and 2015, average ozone levels dropped by about 0. 65 parts per billion each year. But around 2015, something changed. Wild
