"Canadian Wildfire Smoke Returns, Millions Under Air Quality Advisory"

Air quality in the northern and eastern US is rapidly declining as hundreds of Canadian wildfires burn out of control, with twenty US states under air alerts. Major Canadian cities are also affected, prompting the deployment of federal troops to fight the fires. Health officials in both countries are warning of medium to high smoke risk, and residents are advised to limit outdoor activities. The wildfires have resulted in the deaths of two Canadian firefighters, and a nine-year-old boy's death may also be linked to the smoke. This summer, Canada has experienced its worst wildfire season on record, with over 24 million acres burned so far. Climate change is increasing the risk of such wildfires.