Wildfire smoke from the western U.S. has reached Baltimore, and was worsening air quality as temperatures and humidity surged Thursday.
A "Code Orange" air quality alert is in effect, indicating unhealthy conditions for sensitive groups including children, the elderly and people with heart or lung disease.
Maryland Department of the Environment air quality forecasters said air pollution is “elevated due to the presence of residual smoke transported from western US/Canada wildfires.” They said expect that to continue into Friday.
Air quality is also poor because of dirty, hot and humid air flowing into the region from the south, forecasters said.
Temperatures reached at least 91 degrees Thursday afternoon at Baltimore/Washington International Thurgood Marshall Airport. High humidity made it feel as hot as 98 degrees.
Even without the wildfire smoke, heat and sunshine spur chemical reactions with vehicle and industrial exhaust to create ozone pollution, which can cause or exacerbate breathing problems.
Friday could be even hotter and more humid, with highs in the lower 90s and a heat index of around 101 degrees.
Cooler temperatures, with highs in the 80s, are forecast for the weekend and into early next week.