What to know about the Canadian and US wildfires and their impact

Wildfires in Ontario, Canada, are generating smoke that is traveling southeast, impacting cities in both the US and Canada, including Toronto, New York State, and Boston. Satellite imagery confirms this widespread smoke plume. Air quality tracking company IQAir has identified Detroit, Toronto, and Minneapolis as having the worst air quality globally due to this smoke. The smoke contains hazardous pollutants like PM2.5 and nitrogen dioxide, which can cause inflammation in the lungs and exacerbate existing respiratory, heart, kidney, and eye conditions. Emergency responders, vulnerable individuals with chronic illnesses, and children are identified as being at the highest risk.

Smoke from over 180 active wildfires in Canada and parts of Minnesota has spread across more than 20 US states, prompting air quality alerts for millions of Americans. Unhealthy to hazardous air conditions are expected through at least Friday, with some areas experiencing "very unhealthy" or "hazardous" air. Authorities are urging residents in affected regions, including New York, Michigan, and Illinois, to stay indoors and reduce outdoor activity. New York City has extended its heat emergency plan and is distributing N95 masks. Forecasters anticipate smoky conditions may persist into the weekend in some areas.

Over 800 wildfires are currently burning across Canada, with the majority out of control. These fires are generating significant smoke plumes, causing hazardous air quality alerts to extend into multiple US states, including Michigan, Minneapolis, and Minnesota. The US Air Quality Index program has deemed air quality in these regions "hazardous," advising residents to stay indoors. Air quality alerts from the NOAA span the Upper Midwest, Great Lakes region, and the US Northeast. Fires in western Ontario are a primary source of the smoke affecting cities like Thunder Bay and Toronto, with some smoke drifting over the Great Lakes and New York. While thunderstorms are expected in Ontario, their impact on the fires is uncertain.

Smoke from over 100 wildfires in northern Ontario has caused Toronto's air quality to become the worst globally, prompting Environment Canada to issue health warnings. The sky over the city turned a "sickly yellow" on Wednesday due to the smoke, which has also affected cities across the northeastern United States. Mandatory evacuations have occurred in several First Nations communities in northwestern Ontario, with some, like Collins, being destroyed. The region is also experiencing a heatwave. Air quality alerts have been issued in parts of Michigan, Minnesota, and Wisconsin, with forecasts predicting thicker smoke to move towards New York and other eastern seaboard cities.