MPCA: Wildfire smoke likely at record levels for Minnesota

Unprecedented magnitude and duration of thick wildfire smoke up north

Air quality index at 3 pm Tuesday
Air quality index at 3 p.m. Tuesday
Minnesota Pollution Control Agency

The thick plume of wildfire smoke drifting across Minnesota Tuesday is likely the highest ever recorded according to data from the Minnesota Pollution Control Agency (MPCA).

The particulate matter reading on the MPCA air quality monitor at Red Lake in northern Minnesota hit 397 micrograms per cubic meter at 2 a.m. Tuesday morning. That’s the highest reading in Minnesota since at least 2000 when MPCA monitors came online. It may also be the highest reading ever recorded in Minnesota.

Air quality readings for particulate matter (smoke) across north-central Minnesota continue to exceed 300 micrograms per cubic meter Tuesday afternoon. Here’s the 24-hour trend for Brainerd.

Air Quality Index at Brainerd
Air Quality Index at Brainerd for the past 24 hours.
Minnesota Pollution Control Agency

Here’s more from my exchange Tuesday afternoon with MPCA meteorologist David Brown with the Risk Evaluation & Air Modeling Unit at the Minnesota Pollution Control Agency:

Is that the highest reading today? This year?

The highest one-hour fine particle measurement at one of our monitors was at Red Lake at 2 a.m. The reading was 397 micrograms per cubic meter. For context, the ambient air quality standard is 35.5 micrograms per cubic meter averaged over a 24-hour period. This is the highest reading this year and is certainly one of the highest measured in Minnesota. I would need more time to confirm if it’s the all-time high.

What is the record for highest particulates?

This is likely the highest value measured in Minnesota by one of our regulatory monitors. However, fine particles have only been measure by our widespread monitoring network since about 2000.

Any other perspective on today’s numbers?

Over the past several years there have been just a handful of events where fine particle concentrations have gotten this high. The fireworks over Independence Day in 2020 produced a one-hour value of 277 micrograms per cubic meter in south Minneapolis. Red Lake measured a value of 222 micrograms per cubic meter on July 6, 2019 due to wildfire smoke. There was a wildfire smoke event on May 7 through May 8, 2016 that produced a one-hour value of 353 micrograms per cubic meter in St. Michael at 1 a.m. on May 7.

When concentrations get this high, it is almost always due to wildfire smoke, and these levels usually only last a few hours. This current wildfire smoke event is unprecedented not only for the magnitude of the hourly concentrations but the duration as well. The concentrations have been in excess of 200 micrograms per cubic meter for the last 13 hours.

An air quality alert continues for most of Minnesota until 6 a.m. Thursday.

Your support matters.

You make MPR News possible. Individual donations are behind the clarity in coverage from our reporters across the state, stories that connect us, and conversations that provide perspectives. Help ensure MPR remains a resource that brings Minnesotans together.