Cumulative solid fuel use for cooking and heating shows monotonic linear dose-response relationships with all-cause and cardiovascular mortality, partially mediated by pulmonary function, blood pressure, and hematological markers.
Each 50 h-year increase in cumulative biomass use for cooking was associated with significantly higher all-cause mortality risk.
Each 50 h-year increase in cumulative biomass use for cooking was associated with significantly higher cardiovascular mortality risk.
Biomass and coal use for heating also showed positive associations with all-cause and cardiovascular mortality.
The exposure-response relationships between cumulative solid fuel use and mortality followed monotonic linear patterns.
Fuel stacking (concurrent use of multiple fuel types) was common among the study population.
Pulmonary function indices, blood pressure, and specific hematological markers partially mediated the association between solid fuel use and mortality.
Household air pollution from solid fuel use affects approximately 2.67 billion people globally.
This research followed over 45,000 Chinese adults for nearly 11 years to understand how long-term use of solid fuels — such as wood, coal, and other biomass — for cooking and heating affects the risk of dying from any cause or from cardiovascular disease. Rather than simply categorizing people as solid fuel users or not, the researchers developed a cumulative exposure measure that accounts for how long someone used these fuels, how often, and what type — giving a more precise picture of lifetime exposure. They found that the more cumulative exposure a person had to biomass cooking fuels, the higher their risk of death, with each additional 50 'hour-years' of exposure linked to an 18% higher risk of all-cause death and a 22% higher risk of cardiovascular death compared to clean fuel users. Similar patterns were seen for heating fuels. Importantly, the relationship between exposure and risk was linear — meaning there was no apparent 'safe' threshold, and risk increased steadily with greater cumulative exposure. The study also found that a quarter of participants used multiple fuel types simultaneously (called 'fuel stacking'), and the analyses accounted for this complexity. Biological analyses suggested that the harm from solid fuel smoke operates at least in part through reduced lung function, elevated blood pressure, and changes in blood cell markers, though these factors only partially explained the increased death risk, pointing to other mechanisms still to be identified. This research suggests that reducing solid fuel use over a lifetime — not just switching fuels at a single point in time — is important for protecting health, and that people with long histories of solid fuel exposure may benefit from early clinical monitoring of lung function, blood pressure, and blood health markers. Given that nearly 2.67 billion people worldwide still rely on solid fuels, the findings highlight a substantial and ongoing global health burden.
Pang L, Yan J, Han X, Wu S, Pan Z, Li Z, et al.. (2026). Cumulative Household Solid Fuel Use, Mediating Factors, and All-Cause and Cardiovascular Mortality in Chinese Adults: A Prospective Cohort Study.. Environmental science & technology. https://doi.org/10.1021/acs.est.6c03531