Smoke from Canadian wildfires continues to worsen air quality across the Midwest and parts of the Northeast. The Canadian wildfires have been burning since mid-May and, as of Wednesday, June 4, there are 203 active fires, according to the Canadian Interagency Forest Fire Centre. Of those fires, only 70 are under control.

(Reuters) -Smoke from wildfires burning in three Canadian provinces covered about a third of the U.S. on Wednesday, forecasters said, but had little effect on air quality except in New England and parts of New York state and the Midwest.