Experts explain Minnesota’s smoky, hazy summer

City of Minneapolis skyline on a poor air quality day. Smoke and haze obstructs the view of the city.

Hazy skies and the persistent smell of bonfire have been a regular occurrence across Minnesota this summer. There’s been a record number of recorded poor air quality days, and once the skies clear, there’s uncertainty around if and when the haze will return. Environmental Initiative recently sat down with experts at the Minnesota Pollution Control Agency (MPCA) to learn more about air quality forecasting, recent air quality trends, and what people can do to stay safe.  

The conversation with Matthew Taraldsen, MPCA supervisory meteorologist, and Tyler Ellis, neighborhood air pollution lead, has been edited for length and clarity.  

At the time of this conversation, the MPCA has issued a record 24 air quality alerts so far this year. I imagine you’ve had a very busy summer. What is the process of forecasting and issuing an air quality alert like?

Matthew Taraldsen: The MPCA produces daily air quality forecasts for levels of fine particles and of ground-level ozone from March through October in 18 locations throughout Minnesota. When the forecast for the air quality index (AQI) values is near or exceeds 101, an air quality alert is issued.  

Fine particles and ground-level ozone are two types of air pollutants most likely to affect people’s health and make existing heart and lung conditions worse. We release fine particles when we burn gasoline, diesel, or wood. They can also form when gaseous pollutants react in the air. Ground-level ozone forms through chemical reactions of molecules already in the air, such as nitrogen oxides (NOx) and volatile organic compounds (VOCs). 

MPCA meteorologists primarily forecast weather conditions, and there are certain types of weather conditions that can negatively impact air quality. To determine how wildfires impact air quality, we look where the fires are, where the air masses are traveling, and the thermodynamic environment. We’ve had many days where wildfire smoke is thousands of feet up in the atmosphere, and the air quality is great here. Strong low-pressure or high-pressure systems or strong cold fronts will push that air down, resulting in poor, smoky air quality like we’ve been seeing recently. A big part of our job at the MPCA is analyzing the weather models to figure out what is going on. It’s as much of an art as it is a science.  

Our team will discuss the weather models and create a forecast based off our interpretation. If we determine air quality levels will be high enough to warrant an air quality alert, we collaborate to write up a statement, draw up a map, and then the messaging goes out on our channels and to our distribution network. Alerts include information about when air quality fluctuates during the day so people can make informed decisions about when to be outside.  

Wildfires are common every summer, but why is there more smoke reaching Minnesota this year? Can we expect seasons with a higher number of alerts to be more common or is this year an anomaly?

Matthew Taraldsen: This year we are seeing the duality of a strong El Niño pattern and longer, more intense fires fueled by climate change. The El Niño pattern is impacting where the smoke goes and how long it lingers. The Jetstream that typically pushes air over the Upper Midwest is currently up above Canada, so the warm air that gives us summer thunderstorms and fuels our weather is near the Hudson Bay. There’s been longer days of poor air quality here because the Jetstream isn’t around to help with air flow, and the smoky air is sticking around for longer periods.  

We don’t know if climate change is amplifying the La Niña/El Niño pattern, but we do know that climate change is causing warmer temperatures, more weather variability, and less precipitation, and those conditions are ripe for more intense, longer, and larger wildfires. There were large wildfires out West and up in Canada last year, and we didn’t have many poor air quality days because the smoky air passed over us through the Jetstream.  

There’s been news articles recommending that people limit outdoor activities, wear an N95 mask, and keep windows closed. Are there other proactive things people can do so they are prepared for future air quality alerts?  

Matthew Taraldsen: The most important thing people can do is pay attention. We forecast and highlight current conditions on our website, and information is also available on the AirNow website, which is managed by the U.S. Environmental Protection Agency (EPA).  

It is also good to keep N95 masks handy. It is crucial that an N95 mask be properly fitted to protect from the particulate matter in smoke. We also recommend keeping windows closed. If there’s a wall air conditioning unit, put a towel around it to limit gaps that smoke can get through. It’s a common misconception that people can’t go outside when there’s poor air quality. You can, but we encourage potentially limiting time outside and outdoor exertion. If you develop symptoms such as burning eyes, a sore throat, or a cough, take it easy and go indoors.  

Exposure to ozone can trigger your body’s defense mechanisms. Inflammation response builds up the longer you’re exposed to ozone, even at smaller levels. If ground-level ozone numbers are higher, it’s better to go outside in the morning or late at night when the levels drop. For wildfire smoke, it’s best to go outdoors at the peak of the afternoon when the atmosphere is well mixed. 

The MPCA is refining its messaging around wood smoke, can you talk about how the recent air quality alerts are presenting opportunities and challenges around that?

Tyler Ellis: Smoke exposure is on people’s minds, so it’s a great opportunity to discuss residential and recreational wood burning, its impacts, and how to reduce exposure. Wood burning  (and wildfires) releases a variety of air pollutants that are bad for public health — carbon monoxide, dioxins, volatile organic compounds, particulate matter. It can be hard to think a bonfire or wood burning stove can make a difference with air quality when massive wildfires and climate change are having much larger, more visible impacts. But these smaller, more dispersed sources of air pollution add up and contribute to local pollution. 

The MPCA team has been educating the public on the harms of wood smoke and ways to reduce wood smoke exposure, especially on days when the air quality is already poor from wildfire smoke. We put out messages encouraging people to avoid using wood burning stoves or having backyard fires. There are also resources available to reduce exposure by replacing old wood stoves or upgrading to a non-wood burning heat pump. Right now, eligible Minnesotans can also receive discounts to upgrade their wood stove through Environmental Initiative’s Project Stove Swap program 

Can you explain the link between wildfire smoke, wildfires, and climate change?

Matthew Taraldsen: We’re experiencing warmer temperatures that are more favorable for wildfires because of climate change. The increased variability in weather also promotes wildfires and messes with the heat equilibrium of Earth’s systems, making the Jetstream less predictable. There may be dramatic flash events of intense wet periods followed by intense droughts. Minnesota had a really intense drought last year, followed by a record amount of snow during the winter, and now we are back in a drought again. These flip flops are really a hallmark of climate change. 

Air pollution and climate change are connected. They both involve the accumulation of pollutants in the atmosphere. Researchers are developing tools to help governments and other decision-makers deploy strategies that address air pollution and climate change at the same time. To address climate change, air quality and public health, we will need many strategies. 

Voluntary emission reduction efforts through MPCA’s partnership with Environmental Initiative and Clean Air Minnesota are just a few examples – reducing smoke from wood burning appliances, cleaning up older diesel engines, helping autobody shops switch to waterborne paint – all these things can add up to big emission reductions. 

If you are interested in learning more about air quality and Minnesota’s voluntary emission reduction efforts, sign up for Environmental Initiative’s quarterly Clean Air Minnesota newsletter. Clean Air Minnesota is a coalition of air quality leaders convened by Environmental Initiative who are working voluntarily and proactively to reduce man-made sources of fine particulate matter (soot) and ground-level ozone (smog).