Even a cozy winter fire could be silently harming your health-and the air quality of cities nationwide. New research from Northwestern University reveals that residential wood burning contributes to more than one-fifth of Americans’ winter exposure to dangerous fine particulate matter (PM2.5), despite only 2% of U.S. households relying on wood as their primary heating source.
Hidden Pollution: The Unexpected Impact of Wood Burning
A surprising source of winter air pollution is impacting public health,notably in urban areas.
- Residential wood burning accounts for approximately 22% of wintertime PM2.5 pollution in the U.S.
- Urban communities experience greater health risks from wood smoke than rural areas.
- People of color are disproportionately affected,facing higher exposure and health harms despite lower wood-burning rates.
- an estimated 8,600 premature deaths each year are associated with pollution from residential wood burning.
These microscopic particles,known as PM2.5, are small enough to penetrate deep into the lungs and bloodstream, increasing the risk of heart disease, lung disease, and even premature death. Researchers estimate that 8,600 premature deaths each year are associated with pollution from residential wood burning.
The study, published in the journal Environmental Science & Technology, highlights a concerning disparity: people of color are disproportionately exposed to wood smoke pollution, even though they are less likely to be burning wood themselves.
lipak, who led the study at Northwestern, added, “People of color face both higher baseline mortality rates and higher rates of exposure to pollution from wood burning. Though, people of color are correlated with lower emissions rates, indicating that a large fraction of this pollution is transported to these communities, rather than emitted by them.”
Mapping the Pollution
For decades, air quality research has primarily focused on emissions from vehicles, power plants, and wildfires. This study shifted the focus to a less-studied source: wood burning in homes, including furnaces, boilers, fireplaces, and stoves. The research team utilized data from the National Emissions Inventory (NEI), a database maintained by the U.S. Environmental protection Agency, which estimates emissions based on household surveys, housing characteristics, and climate conditions.
They then applied a high-resolution atmospheric model to simulate how pollution travels through the air, factoring in weather patterns, wind, temperature, and terrain. By dividing the continental United states into a 4 kilometer by 4 kilometer grid, researchers were able to pinpoint pollution hotspots with greater accuracy than broader averages allow.
“Wood burning emissions enter the atmosphere, where they are affected by meteorology,” Horton said. “Some emissions are considered primary pollutants, such as black carbon, and some interact with the atmosphere and other constituents, and can form additional, secondary species of particulate matter pollution.”
By comparing model runs with and without residential wood burning emissions, the researchers persistent that wood burning accounts for about 22% of wintertime PM2.5 pollution, making it a significant contributor during the coldest months.
“long-term exposure to fine particulate matter is associated with an increased risk of cardiovascular diseases,” Shlipak said. “Studies have shown consistently that this exposure leads to a higher risk of death. Our study suggests that one way to substantially reduce this pollution is to reduce residential wood burning. Using option appliances to heat homes instead of burning wood would have a big impact on fine particulate matter in the air.”
Horton, an associate professor of Earth, environmental and planetary sciences at Northwestern’s Weinberg College of Arts and Sciences, directs the Climate Change Research Group (CCRG). Shlipak is an undergraduate in mechanical engineering at Northwestern’s McCormick School of Engineering and a member of the CCRG.
The researchers acknowledge that their study focused solely on outdoor exposure to wood burning pollution, and did not include the health effects of indoor exposure, which also pose significant public health risks.
The study, “Ambient air quality and health impacts of PM2.5 from U.S. residential wood combustion,” was supported by the National Science Foundation (award number CAS-Climate-2239834).
