Wildfire smoke ages in the atmosphere

Graphical abstract. Credit: Atmospheric Environment (2021). DOI: 10.1016/j.atmosenv.2021.118929

When emissions, such as smoke from wildfires and vehicle exhaust, enter the atmosphere, they undergo chemical changes. University of Georgia research demonstrates for the first time that these changes may affect the type of treatment patients require to combat exposure to such pollutants.

Rawad Saleh, an assistant professor in the College of Engineering, stated, “We found that after emissions entered the atmosphere, there were changes in their chemical composition that affected how toxic they were.” “The mechanisms of toxicity vary depending on whether you are exposed to smoke directly from a fire or after it has spent time in the atmosphere.”

For the study, which was published in the journal Atmospheric Environment, Saleh and a team from the University of Georgia burned oak foliage, pine needles, and hickory twigs in an environmental chamber before initiating photochemical ageing of the emissions with ultraviolet radiation. They exposed human lung epithelial cells to the resulting aerosol in the laboratory.

How do forest fires influence the lungs?

The aerosol produced by burning biomass is toxic to human lung epithelial cells, and the team’s findings indicate that the type of exposure, such as exposure to fresh versus aged smoke, affects cells differently. Fresh smoke is more damaging to mitochondria, the cellular organelles that process food and produce energy. The increased oxidative stress caused by aged smoke can result in cell death. On the surface, the damage resulting from exposure to emissions can be caused in a variety of ways, despite the fact that it may appear identical.

Multiple people exposed to forest fire emissions may develop chronic obstructive pulmonary disease, according to Saleh. “However, our findings suggest that a person exposed to fresh smoke, such as a firefighter, may require a different COPD treatment than a person exposed to aged smoke 50 miles away from the fire. This is because the disease-causing mechanisms are distinct.”

According to Saleh, elucidating these mechanisms will become increasingly important as the pollutants in our atmosphere evolve. As technology advances, emissions from sources such as vehicles are decreasing, but forest fires are increasing their contribution to pollution as climate change creates warmer and drier conditions.

“Historically, people believed that emissions from forest fires or burning wood were less toxic than emissions from burning fossil fuels, but they have comparable levels of toxicity,” he said. In ten to twenty years, the majority of harmful particles in the air will likely originate from a forest fire somewhere in the world.

Further information: Khairallah Atwi et al, Differential response of human lung epithelial cells to particulate matter in fresh and photochemically aged biomass-burning smoke, Atmospheric Environment (2021). DOI: 10.1016/j.atmosenv.2021.118929

Journal information: Atmospheric Environment

Source: University of Georgia