Wildfires in Minnesota are releasing smoke that could soon become a significant air pollution issue for millions residing in major U.S. cities such as Detroit, Milwaukee, Cleveland, Philadelphia, and New York City.
At the moment, the smoke is mostly high in the atmosphere. However, a forecast from the National Oceanic and Atmospheric Administration indicates this might change soon. The ongoing heat dome over the central U.S. is creating a clockwise air flow, which is likely to drive the smoke down to ground level and toward the southeast in the coming days. Individuals in these areas might face unhealthy to hazardous levels of PM2.5 pollution—tiny, harmful particles in smoke that can penetrate deep into the lungs. In the Air Quality Index, red signifies “unhealthy” while maroon signifies “hazardous.”
Read more: How to Use the Air Quality Index
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The exact levels of pollution and duration of adverse conditions remain somewhat uncertain. Meteorologist Jeff Masters noted in a Bluesky post that “Forecasting wildfire smoke is HARD, and model forecasts are often way off—either high or low.” He added that the models are still in development and need to accurately predict meteorology, fire behavior, and atmospheric chemistry.
The smoke could also result in hazy orange skies, as the particles scatter blue light while letting orange and red wavelengths pass through.
The fires in Minnesota are atypical for this time of year, which is usually wet, with fire season generally occurring in spring or fall. Drought and exceptionally high temperatures have left vegetation dry and susceptible to ignition. Some of these fires were sparked by lightning in the Boundary Waters Canoe Area Wilderness and other parts of the Superior National Forest last week. Steady winds have exacerbated the flames. Parts of the forest are closed to visitors, and Minnesota’s governor Tim Walz has declared an emergency, allowing the National Guard and other resources to combat the fires.
According to Masters, the smoke could intermittently cause air pollution issues over the next 10 days. The best way to protect yourself is to limit outdoor activities, wear an N95 mask when outside, keep doors and windows closed and sealed, and use air purifiers indoors.
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