MPCA: Smoke from wildfires expected to reach record levels for Minnesota


The thick plume of forest fire smoke drifting across Minnesota on Tuesday is likely the highest on record, according to data from the Minnesota Pollution Control Agency. (MPCA)

Particulate matter reading the MPCA air quality monitor in Red Lake, northern Minnesota, reached 397 micrograms per cubic meter as of 2 a.m. Tuesday morning. This is the highest reading in Minnesota since at least 2000 when MPCA monitors came online. It is also possibly the highest reading on record in Minnesota.

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

Brainerd Air Quality Index for the past 24 hours.

Minnesota Pollution Control Agency

Here is more of my discussion on Tuesday afternoon with MPCA meteorologist David Brown of the Minnesota Pollution Control Agency’s Air Modeling and Risk Assessment Unit.

My questions are in bold with his answers below.

Is this the highest reading today? This year?

The highest fine particle reading in one hour on one of our monitors was in Red Lake at 2 a.m. The reading was 397 µg / m ^ 3 (micrograms per cubic meter). For context, the ambient air quality standard is 35.5 ug / m ^ 3 on average over a 24 hour period. It’s the highest reading this year, and it’s certainly one of the highest measured in Minnesota. I would need more time to confirm if this is the all-time high.

What is the record for the highest particles?

This is probably the highest value measured in Minnesota by one of our regulatory monitors. However, fine particles have only been measured by our extensive monitoring network since around 2000.

Another take on today’s numbers ??

In recent years, there have only been a handful of events where fine particle concentrations have become this high (> 200 ug / m ^ 3). The Independence Day fireworks in 2020 produced a 1-hour value of 277 ug / m ^ 3 in southern Minneapolis. Red Lake measured 222 ug / m ^ 3 on July 6, 2019 due to smoke from wildfires. There was a forest fire on May 7-8, 2016 that produced a 1 hour value of 353 ug / m ^ 3 in St. Michael at 1 a.m. on May 7.

When concentrations reach this level, it is almost always due to smoke from forest fires, and these levels usually only last for a few hours. This current wildfire smoke event is unprecedented not only for the magnitude of hourly concentrations, but also for duration. Concentrations have exceeded 200 µg / m ^ 3 during the past 13 hours.

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

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