Scientists from Northwestern University have shown that burning wood in homes contributes significantly to winter air pollution in the United States, even though most people do not consider it a serious source of pollution.
Although only 2% of American homes rely on firewood as their primary source of heating, firewood emissions contribute to more than one-fifth of Americans' exposure to fine particulate matter in the air (PM2.5) during the winter.
These tiny particles can penetrate the lungs and enter the bloodstream, increasing the risk of heart and lung disease, and even premature death. The new study suggests that firewood pollution is linked to approximately 8,600 deaths annually.
It is noteworthy that the majority of those affected live in cities rather than rural areas, and the health burden falls more heavily on ethnic minorities, who burn less firewood but are exposed to higher levels of pollution and greater health damage, possibly as a result of the effects of previous discriminatory policies and their higher underlying mortality rates.
"Long-term exposure to fine particulate matter is associated with an increased risk of cardiovascular disease," said Kian Schleppak, lead author of the study from Northwestern University.
He added: "Studies have shown that this exposure leads to a higher risk of death, and our study indicates that reducing wood burning in homes will have a significant impact on reducing pollution."
Daniel Horton, the study's lead author, emphasized, "We often hear about the effects of wildfires, but we rarely consider the risks of burning wood for heating in our homes." He explained that switching to cleaner or non-combustible heat sources in homes could significantly improve air quality.
The study focused on wood burning in homes, including emissions from furnaces, boilers, and stoves. Researchers collected data from the National Emissions Register and used a high-resolution atmospheric model to simulate pollution transmission through the air, taking into account weather, wind, temperature, topography, and the chemical composition of the atmosphere.
The team divided the United States into a grid of squares, each with sides measuring 4 kilometers, and analyzed the hourly pollution levels and how the pollution spreads and accumulates. The simulation showed that wood burning contributes approximately 22% of fine particulate matter pollution in winter and is one of the largest sources of pollution during the coldest months of the year, particularly in cities and suburbs.
Its impact on population groups
Researchers found that people of color experience greater health effects despite burning less firewood. In the greater Chicago area, Black communities face more than 30% higher negative health impacts from firewood burning than the city average. This is due to the transfer of pollution from the suburbs to densely populated urban areas, as well as environmental pressures resulting from past policies.
Horton said: "The pollutants emitted from firewood travel to densely populated cities, exposing more people and causing greater health effects on ethnic minorities."
The researchers noted that the study focused on outdoor pollution, while indoor exposure to fine particles has general health effects that were not included in the study.
