Wildfire Emissions Analyzed for Health, Climate Effects
John Simpson | November 25, 2016Engineers are recreating wildfires in a laboratory at Washington University in St. Louis to better understand the particulate matter emitted during these increasingly frequent events.
“Wildfires are a big national issue and people are already feeling it,” says Rajan Chakrabarty, assistant professor of energy, environmental and chemical engineering. “The projections show that by 2020 there will be a significant increase in the frequency of these fires in the United States.”
Using fuels taken from wildfire areas across the country, such as pine branches and peat, researchers clad in lab coats, gloves and goggles are lighting fires in controlled experiments to mimic wildfires on a much smaller scale. Their novel approach uses a special chamber that allows the controlled combustion of these fuels under flaming and smoldering conditions, after which the emitted smoke particles are aged photochemically in a flow tube reactor for up to several equivalent atmospheric days.
This enables the researchers to observe and analyze particles as small as 1/100,000th the width of a human hair that are emitted during a forest fire—and their subsequent processing in the atmosphere. It is a process that is virtually impossible to do in nature.
“If we were able to fly all these instruments into a forest fire and then float along with those emissions in the atmosphere for two weeks, we could capture that in real time,” says Brent Williams, associate professor of energy, environmental and chemical engineering. “However, there are a lot of challenges in doing that. These are some large instruments, they take a lot of power and they don’t really fit on aircraft.”
Although they are tiny, the nanoscale-sized particles emitted during these lab-scale fires are providing the researchers massive amounts of information. A better understanding of their chemical properties—and how those properties change during the course of a fire—translates to better, more detailed predictions for scientists as they determine their impacts on both the environment and human health.
"Additionally, the chemical composition of these particles influences their optical properties and even the ability to form clouds, meaning the particles play a role in setting the temperature of our planet,” Williams says.