Canada issues air quality warnings over US wildfire smoke after Trump tariff threat

Officials say smoke from US fires has crossed border days after US president accused Canada of improper fire managementAfter days of acrid smoke from northern wildfires choking major US cities and inspiring Donald Trump to threaten Canada with tariffs, officials now say the reverse is also happening as parts of Canada issue air quality warnings caused by American fires to the south.Officials in the Canadian province of British Columbia warned in an alert on Saturday evening that smoke from US fires, spurred on by thousands of lightning strikes in the north-east, was creating smoky conditions as polluted air drifted north.