Wisconsinites breathed record-breaking levels of air pollution Thursday as wildfire smoke from northern Minnesota and Canada wafted across much of the Great Lakes region and the Northeast. Many monitoring stations across the state recorded pollution considered hazardous for the first time in at least 16 years — the span covered by most monitoring stations’ records.
As of 8 a.m. on Friday, Air Quality Index, or AQI, levels in Madison had peaked above 450 — far above the AQI’s 301 threshold for “hazardous” air quality, where everyone — not just sensitive groups — should take precautions to avoid breathing dangerous air.
Milwaukee’s AQI reached 644 earlier on Thursday — more than twice the hazardous threshold. Air quality deteriorated even further in northwestern Wisconsin, with the index reaching 967 along the Minnesota border earlier in the day.
Many Wisconsin communities, including Milwaukee, Waukesha, Odanah and Appleton, were still observing AQI over the 301 threshold Friday morning.
The index categories typically run only from zero to 500.
Thursday’s pollution surpassed levels once considered unprecedented. Before Canadian wildfire smoke pushed the AQI to record highs across Wisconsin in July 2023, cities including Madison, Milwaukee and Waukesha had not recorded an AQI above 200 since at least 2010, according to a Wisconsin Watch analysis of historical AQI data.
But wildfire smoke has elevated air pollution in Wisconsin each summer since 2023. Major cities have periodically recorded higher AQI readings around July, though Thursday’s levels were the first to surpass those recorded in 2023.
“This is a hazardous air quality episode that we have not experienced before,” Craig Czarnecki, air management outreach coordinator for the Wisconsin Department of Natural Resources, said in an email.
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Wildfires in northern Minnesota and Canada have caused some of the worst air quality on record for Wisconsin. The entire state remains under an Air Quality Advisory for fine particulate matter from wildfire smoke until noon on Friday, according to the Wisconsin Department of Natural Resources.
As of 2 p.m. Thursday, most of the state’s air quality was in the “very unhealthy” or “hazardous” Air Quality category. That means that everyone, not just sensitive groups, should avoid outdoor activities, the DNR said.
In areas near Superior, the Air Quality Index rose above 800, while parts of eastern Wisconsin including Milwaukee and Kenosha measured above 650. National Weather Service meteorologist Benjamin Sheppard told Wisconsin Watch these levels are some of the worst on record.
“What we’ve heard from some of our partners is that the Air Quality Index values that we’re seeing are definitely either never before seen or up there,” Sheppard said. “I’ve been working here for three years, and I’ve seen nothing anywhere near that high.”
Smoke from wildfires in northern Minnesota and Canada wafted in much of Wisconsin on July 16, 2026, including near the Capitol building in Madison. (Natalie Yahr / Wisconsin Watch)
Index values in Wisconsin have exceeded the records set by wildfires in June 2023, DNR spokesperson Craig Czarnecki said in an email, noting that the figures “will still need to be quality assured.” At that time, levels peaked at 273, which means concentrations in Superior and the Milwaukee area have more than doubled.
A Wisconsin Department of Natural Resources air quality map.
The U.S. Centers for Disease Control and Prevention recommends setting up a portable air cleaner or filter in a room that can be closed off from outside air and setting your air conditioner to recirculate mode if possible or close the outdoor intake damper.
Fine particulate matter, also known as PM2.5, is a main pollutant released from wildfire smoke that can enter the bloodstream. Dr. Joan Schiller, a member of Healthy Climate Wisconsin and retired medical oncologist, told WPR this can exacerbate lung conditions.
“I don’t think people realize how far away you can be from the fire itself and still have health problems,” Schiller said. “These health problems typically manifest themselves as respiratory problems, such as exacerbation of COPD or asthma or emphysema.”
How can I check the air quality in my area?
The Environmental Protection Agency monitors the air around the country and compiles an air quality index, or AQI.
(Courtesy of U.S. Environmental Protection Agency)
Here’s what to know about the index and how to keep tabs on your area, especially in U.S. regions dealing with smoke from Canadian wildfires.
What does the air quality index measure?
The index rates how clean or polluted the air is each day. The EPA uses this measure to keep tabs on five kinds of air pollutants. The main concern from the wildfire smoke is fine particle pollution. These particles are tiny enough to get deep into the lungs. They can cause short-term problems like coughing and itchy eyes and, in the long run, can affect the lungs and heart.
What do the numbers and colors mean?
The index categories typically only run from zero to 500 – although levels have reached well above 500 in multiple parts of the state. The higher the number, the worse the air quality. That range is broken down into six color-coded categories. Green or yellow — in the zero to 100 range — the air is pretty clear. Once it gets up to orange, the air quality could be a concern for sensitive groups like children, older adults or those with health conditions.
In the red and purple zones, the air quality is considered unhealthy for everyone.
And if the index gets to maroon — at 301 or above — pollution levels are hazardous.
At these high levels, take precautions to avoid breathing in the dangerous air. That can mean reducing your outdoor activities, running air purifiers inside and wearing a well-fitting mask like an N95 when you’re outside.
What’s the air quality right now?
Check AirNow.gov, which updates every hour. The site shows a real-time map of the air quality across the country and also includes a forecast for the day ahead. The map pulls in measurements from a network of air monitoring stations across the country. States and cities may also offer more local guidance.
Washington Park in Milwaukee is draped in smoke from wildfires in Canada and Minnesota on Thursday, July 16, 2026. (Jonathan Aguilar / Milwaukee Neighborhood News Service / CatchLight Local)
How long will smoke last in Wisconsin?
According to Sheppard and the National Weather Service (NWS), a southerly wind on Friday means smoke is anticipated to retreat from west to east – likely bringing an end to the advisory for much of the state.
“With those southwest winds, the air is going to get kind of clearer and healthier in a southwest to northeast manner,” Sheppard said. “Areas further north and east in Wisconsin are going to be most likely to hang on to that smoke.”
Areas along Lake Superior may also need to have the advisory extended, NWS said. But Sheppard said winds could bring back a second wave of smoke to the rest of the state as soon as Saturday.
“The weather models tentatively are telling us that the second batch of smoke could be as strong, or perhaps even worse,” he said.
The Associated Press contributed reporting, as did Hongyu Liu of Wisconsin Watch.
Wisconsin Watch is a nonprofit, nonpartisan newsroom. Subscribe to our newsletters for original stories and our Friday news roundup.
In addition to being a health hazard for anyone living downwind of the coal-burning plants, coal is more expensive and less reliable than other cleaner sources for power. (Photo of AES Indiana's Petersburg Generation Station by Robert Zullo/States Newsroom)
Recent administrative efforts to endorse new coal-fired power plants and repair outdated plants are making my blood boil. For more than 30 years, I have worked tirelessly along with thousands of other public health and climate scientists to understand the very real public health threats posed by burning fossil fuels like coal. Coal-fired power plants are some of the worst offenders when it comes to causing harm to human health and the environment. In addition to being a health hazard for anyone living downwind of the coal-burning plants, it’s more expensive and less reliable than other cleaner sources for power.
Let’s look at some of the reasons why coal is bad for health.
When coal is burned in power plants, it releases soot – tiny particles that get deep into people’s lungs and bloodstreams. Mercury in soot is also a severe health hazard because it releases a potent neurotoxin that contributes to many chronic illnesses. Exposure to soot is linked to cancer, respiratory disease, heart disease, neurological and developmental disorders. Children and senior citizens are particularly vulnerable to impacts from coal-fired soot.
Coal ash, the hazardous residue left after coal is burned, is a concoction of toxic metals (like lead, mercury and arsenic), cancer-causing compounds, and other dangerous substances. Power plants produce about 70 million tons of it each year. In April 2026, the Trump EPA proposed weakening federal coal ash standards.
In 2023, a study published in Science magazine reported that:
Air pollution from coal power plants is associated with greater mortality than previously thought.
Such deaths have decreased due to air pollution regulations and coal power plant retirements.
Coal is not cheap
Prior to this administration, many utilities had already started phasing out coal plants in favor of clean energy because coal plants often need expensive repairs and emit costly, dirty fuel. Coal power is so expensive that, according to a 2023 study, 99% of the time it would be cheaper to get electricity by building entirely new wind and solar farms than it would be to buy power from existing coal plants.
The Trump administration announced plans to provide up to $500 million in funding to coal-fired power plants in 10 states, along with an export terminal in California. The Columbia Energy Center, coal-fired plant co-owned by Alliant Energy, Madison Gas and Electric, and Wisconsin Public Service near Pardeeville, is expected to receive $19 million in federal funding for a modernization project. The plant was originally scheduled to retire by 2024. Alliant is exploring a gas conversion for one of the two primary generating units, so there is a potential for continued operations beyond the end of 2029 (the updated retirement date for the facility).
Note the Columbia plant has released more emissions of the health-harming pollutants nitrogen oxides and sulfur dioxide than any other Wisconsin coal-fired power plant from 2019 to 2023, the most recent five years for which data are available.
Additional costs for coal-fired energy also come from federal taxpayers subsidizing the industry for nearly 100 years. In 2026, the subsidies will be around $5.5 billion. Plus think about all the additional costs that taxpayers must absorb from the impacts of air pollutants on their health – at a time when healthcare subsidies have lapsed for millions of Americans.
There is no such thing as clean or cheap coal. As we approach America’s 250th anniversary, it’s more than time for a real Energy Independence Day from throwback policies that harm Americans and a focus on cleaner energy sources that protect human health and the environment.
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