Large wildfires can be a major contributor to degraded air quality, said Shawn Urbanski, a research physical scientist at the U.S. Forest Service’s Rocky Mountain Research Station who is working to improve a national wildfire pollution emissions inventory.
Much of the degradation comes from microscopic particulate matter known as PM2.5, which is particulate matter less than 2.5 micrometers, which can cause health problems. Smoke also produces ozone, another pollutant.
In 2011, wildfires were responsible for 35 percent of fine particulate matter pollution, the No. 1 source in the country, Urbanski said.
Second highest was dust, which accounted for 21 percent of the emissions, then agriculture (15 percent) and fuel combustion (13 percent).
The wildfire emissions inventory is basically a compilation of mass emissions of pollutants released by fires at a given time. It’s retrospective, meaning the inventory is released one to two years after burning occurs.
States develop emission control strategies to reduce emissions from a variety of sources to maintain clean air, Urbanski said.
“They need to account for these emissions when they do their modeling,” he said.
The inventory assists states in developing their emission control strategies.
To calculate the inventory, four inputs are needed: area burned, the amount of burnable biomass present, how much of the biomass burns and the emissions factor, which describes how much pollution was released when vegetation burned.
The inventory is done retrospectively because one of the major inputs is areas burned and one of the best techniques to measure that is satellite imagery. High-resolution satellites take the pictures.
Urbanski’s research focuses on developing an improved wildfire emissions inventory.
It’s highly variable where wildfire smoke goes, Urbanski said.
Smoke from boreal forests in Russia sometimes ends up in the United States. There are instances where smoke from fires in the West and Canada impacts Minneapolis and Chicago.
Larger fires produce more smoke and it goes higher into the atmosphere and winds can transport it quickly, Urbanski said
“A lot of the severe impacts tend to be these larger fire events that continue for multiple days,” he said.
Karl Puckett is a Montana-based natural resources reporter.