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

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

The particle reading on 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.

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

Is this the highest reading today? This year?

The highest fine particle measurement in one hour on one of our monitors was taken in 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 on average over a 24-hour period. This is the highest reading this year and 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 reached this level. The Independence Day fireworks in 2020 produced an hourly value of 277 micrograms per cubic meter in southern Minneapolis. Red Lake measured 222 micrograms per cubic meter on July 6, 2019 due to smoke from wildfires. There was a wildfire from May 7-8, 2016 that produced an hourly value of 353 micrograms per cubic meter 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 micrograms per cubic meter in the past 13 hours.

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