Long-term coexposure to indoor solid fuels, outdoor air pollution, and heatwave increased the risk of Cardiometabolic Multimorbidity and its core component diseases, with indoor solid fuels use as the primary contributor.
Indoor solid fuel use significantly increased the risk of heart disease and stroke as individual exposures.
PM1, PM2.5, and PM10 were the most consistent risk factors for CMM, diabetes, and heart disease across single-exposure analyses.
Heatwave exposure was sometimes associated with higher risks of CMM, diabetes, and heart disease.
Cumulative Risk Index (CRI) analysis showed that coexposure to multiple environmental factors increased the risks of CMM, diabetes, and heart disease.
The Quantile g-computation (Qgcomp) model showed that coexposure to all environmental factors significantly increased the odds of all four diseases, with indoor solid fuels as the primary contributor.
The study used longitudinal data from five waves of the China Health and Retirement Longitudinal Study (CHARLS) spanning 2011 to 2020.
This research suggests that being exposed to multiple environmental hazards at the same time — specifically indoor solid fuel burning (such as coal or wood for cooking and heating), outdoor air pollution (measured as fine and coarse particulate matter: PM1, PM2.5, and PM10), and heatwaves — significantly raises the risk of developing cardiometabolic diseases including diabetes, heart disease, and stroke, as well as having two or more of these conditions simultaneously (called Cardiometabolic Multimorbidity, or CMM). The study followed more than 10,000 middle-aged and older adults in China over nearly a decade using data from a large national survey, tracking who developed these diseases over time. When looking at individual exposures, outdoor particulate matter pollution was the most consistent risk factor for CMM, diabetes, and heart disease, while indoor solid fuel use was linked to higher risks of heart disease and stroke. Heatwaves were also sometimes associated with higher disease risk. Crucially, when researchers assessed the combined effect of all these exposures together using statistical models designed for mixed exposures, the risk of developing all four health outcomes was substantially elevated — for example, the combined exposure was associated with a 65% higher odds of CMM and a 67.5% higher odds of diabetes. Indoor solid fuel use emerged as the single largest contributor to these combined risks. This research suggests that reducing exposure to indoor solid fuel combustion — for instance, by switching to cleaner energy sources for cooking and heating — could be one of the most impactful ways to lower the burden of cardiometabolic diseases among older populations in China and similar settings. The findings also highlight that outdoor air pollution and extreme heat events compound these risks, pointing to the importance of addressing multiple environmental exposures together rather than in isolation when designing public health policies.
Kong W, Zheng H, Zhu M, Zhang M, Wang J, Zhong W, et al.. (2026). Association of coexposure to indoor solid fuels, outdoor air pollution, and heatwave with the risk of Cardiometabolic Multimorbidity among middle-aged and older Chinese adults.. International archives of occupational and environmental health. https://doi.org/10.1007/s00420-026-02232-4