- Toxic wildfire smoke is choking millions of Americans on Thursday.
Air quality alerts have been issued across 14 states as a thick plume from Canadian wildfires pours into the Midwest and Northeast.
The affected states are Minnesota, Michigan, Illinois, Indiana, Ohio, Pennsylvania, West Virginia, New York, Vermont, New Hampshire, Massachusetts, Connecticut, Rhode Island and New Jersey.
Detroit ranked as the most polluted major city in the world Thursday morning, recording a hazardous live Air Quality Index (AQI) of 426, as Minneapolis ranked third with an AQI of 349. Good AQIs range from 0 to 50.
Officials have warned that wildfire smoke contains fine particulate matter, also known as PM2.5, which consists of microscopic particles of toxic compounds, small enough to penetrate deep into the lungs and enter the bloodstream.
The US Environmental Protection Agency (EPA) has connected breathing in PM2.5 to multiple health issues, including aggravated asthma, decreased lung function, irregular heartbeat, heart attacks and premature death for those with heart and lung disease.
Most alerts remain in place until midnight Thursday, while warnings across Minnesota are expected to continue until 11am Friday and could be extended if dense smoke persists.
'Any exposure to the air, even for a few minutes, can lead to serious health effects on everybody,' Plume Labs, which tracks and forecasts air pollution, said. 'Avoid outdoor activities.'
The sprawling emergency comes as hundreds of wildfires continue burning across Canada, sending smoke across the border and into densely populated sections of the US.
Michigan is under a statewide air quality alert after plumes from Canadian wildfires spread through the Upper Peninsula and continued sinking south toward the Indiana border.
State officials said pollution could range from unhealthy for sensitive groups in southern Michigan to unhealthy farther north, with hourly concentrations potentially reaching very unhealthy or h
