News Canadian fires trigger more air quality warnings across US; 80M face heat warnings July 17, 2023Isabelle Butera, John Bacon and Doyle Rice, USA TODAYComments Off on Canadian fires trigger more air quality warnings across US; 80M face heat warnings Unrelenting smoke drifting down from almost 1,000 Canadian wildfires triggered more air quality alerts across the U.S. and would last through Tuesday.