Lighting a fire on a cold winter night may feel comforting, but a new study suggests it could pose serious health risks—even for people who do not burn wood themselves.

Researchers at Northwestern University, Illinois in the United States, have found that residential wood burning accounts for about 22 per cent of outdoor fine particle pol‑ lution (PM2.5) during winter across the United States, despite the fact that only about two per cent of households rely on wood as their primary heat‑ ing source.

The findings were published in ‘Science Advances’. PM2.5 particles are extremely small and dangerous, capable of pen‑ etrating deep into the lungs and entering the bloodstream. Long-term expo‑ sure has been linked to heart disease, lung disease and premature death.

According to the study, pollution from residential wood burning is associated with an estimated 8,600 premature deaths annually. “Long-term exposure to fine particulate matter is associated with an increased risk of cardiovascular diseases,” said lead author Kyan Shlipak, an undergraduate mechanical engineering student at North‑ western University.

He added that reducing residential wood burning could significantly cut this form of pollution, noting that alternative home-heating appliances would have a major impact on air quality.”