What Chemical Compounds are Found in Montana Wildfire Smoke?

Montanans know that our skies become filled with thick smoke every summer.

The wildfire smoke usually begins blanketing the state in mid-July and typically doesn't go away until late September or early October - often when the snow flies in the higher elevations.

Read More: Rising Above the Smoke

The smoke is nearly impossible to escape.

Two weeks ago we visited Southwest Montana and it was smokey. Last weekend we drove to the Hi-Line, and it was smokey from Billings to Canada. With 53 active wildfires in Montana (12 new in the last 24 hours, as of 7/30/24), it's easy to assume our haze-filled skies are from local fires. However, the jetstream usually dumps us with smoke from fires in Idaho, California, Washington, other western states, and Canada.

Yeah, it's smoke... but what's in the smoke?

I'm a science dork, so I went poking through some data today to see exactly what chemical compounds are typically found in wildfire smoke. According to Chapter 4 of a USDA report titled "Chemical Composition of Wildland Fire Emissions", here's what we're breathing this summer:

• Carbon dioxide
• Methane
• Nitrous oxide
• Carbon monoxide
• Nonmethane volatile organic carbon
• Nitrogen oxides
• Fine and coarse particulate matter

Fine particulate matter is classified as particles smaller than 2.5 micrometers (a human hair is 70 micrometers). Coarse particulate matter is airborne junk larger than 10 micrometers. Most of the smoke-related haze in Montana is listed as PM 2.5.

Yuck, right?

The exact composition of these smoke-filled skies can vary depending on what's burning. For example, grassland fires can produce different smoke than heavily timbered forests or structure fires.

Air quality monitoring equipment is set at stations across the state and reports are available from a variety of sources. I like IQAir.com, which on Tuesday (7/30) shows particulate levels across numerous cities in southern Montana as  "Unhealthy for Sensitive Groups."