Wildfire smoke continues to impact air quality and travel in the US.

The wildfire smoke that hit the eastern United States this week sent air quality to record lows, with schools closing and outdoor activities canceled. The smoke came from wildfires in Canada, where a hot, dry summer intensified by human-caused climate change is expected to keep fires raging. The smoke event this week was unprecedented, with nearly 60 million people exposed to high levels of smoke pollution on Wednesday alone. While the smoke and air quality are gradually improving, as long as fires burn in Canada, there is the possibility of more smoke onslaughts in the coming weeks.