Biomass burning—whether from wildfires, wood stoves or agricultural fires—sends massive amounts of tiny particles and chemicals into the air. These emissions are not just an environmental issue; they pose serious health risks, especially for our lungs. An Environmental Pollution study, co-authored by Dr. Jason Surratt, a professor in the Department of Chemistry at UNC-Chapel Hill, reveals how two key components of biomass smoke—levoglucosan and 4-nitrocatechol—affect human lung cells. Their findings suggest that aged smoke, which has undergone chemical changes in the atmosphere, could be even more dangerous than fresh smoke.
Biomass burning refers to the combustion of organic materials like wood, leaves and crop residues. This process releases large amounts of carbon-based aerosols, which contribute to air pollution. Among the many chemicals produced in the smoke, levoglucosan and 4-nitrocatechol serve as important markers. Levoglucosan is a sugar-like compound released when wood burns, while 4-nitrocatechol forms when smoke interacts with nitrogen oxides in the atmosphere, a process known as chemical aging. While scientists have long studied the environmental effects of biomass burning, less is known about how these compounds directly impact human health.
In the study, " Evidence for Cytotoxicity and Mitochondrial Dysfunction in Human Lung Cells Exposed to Biomass Burning Aerosol Constituents: Levoglucosan and 4-nitrocatechol ," Dr. Surratt and colleagues at the UNC Gillings School of Global Public Health, Polish Academy of Sciences and Príncipe Felipe Research Center Foundation (CIPF) conducted laboratory experiments to compare how levoglucosan and 4-nitrocatechol affect human lung cells.
They used two different types of lung cells: BEAS-2B cells, which represent normal lung-lining cells, and A549 cells, which come from lung cancer tissue and are commonly used in respiratory studies. The researchers exposed these cells to different concentrations of levoglucosan and 4-nitrocatechol over 24 and 48 hours. They then measured cell survival, stress levels and signs of damage to the cells' mitochondria—the "power plants" of cells that generate energy.
Their key findings were that aged smoke is more toxic:
- The study found that 4-nitrocatechol was significantly more toxic to lung cells than levoglucosan. At relatively low doses, 4-nitrocatechol reduced cell survival and caused oxidative stress—an imbalance that damages cells and can lead to lung diseases.
- Exposure to 4-nitrocatechol disrupted the function of mitochondria in lung cells, leading to a process called apoptosis, or programmed cell death. This damage could contribute to long-term lung problems.
- While levoglucosan exposure also led to cellular stress, its effects were much less severe compared to 4-nitrocatechol. Cells exposed to levoglucosan showed signs of mitochondrial stress, but they were able to recover over time.
- Since 4-nitrocatechol forms when biomass smoke reacts with urban air pollutants like nitrogen oxides, areas affected by both wildfires and traffic pollution may be particularly at risk.
While wearing an N95 or P100 mask can help filter out fine particles, it may not fully protect against toxic gases and chemicals present in aged smoke. Here are some steps individuals can take: Use HEPA air purifiers to remove fine particles from indoor air and keeping windows and doors closed can help minimize smoke infiltration; ensure that homes are properly sealed to prevent smoke from entering through cracks, vents or poorly fitted windows and doors; avoid using candles, gas stoves or burning wood indoors, as these can add to indoor air pollution; in extreme conditions, individuals with respiratory issues or prolonged exposure may consider investing in gas masks with activated carbon filters, which can help remove both particles and harmful gases; and if air quality levels are hazardous and exposure is prolonged, relocating to an area with cleaner air—either indoors with filtered ventilation or to a different location—might be the safest option.
"Our study reinforces concerns that exposure to biomass smoke—especially aged smoke containing 4-nitrocatechol—can have serious health consequences," said Dr. Surratt. "Long-term exposure to these pollutants has been linked to respiratory diseases such as asthma, chronic obstructive pulmonary disease and lung cancer. People who live in wildfire-prone areas or who frequently burn wood for heating should take extra precautions."
