Introduction and objective:
Burning coal and firewood generates toxic emissions that are associated with respiratory illness, cardiovascular disease, and even death. The aim of the study is to evaluate the association between county-level prevalence of household coal and firewood use and health outcomes, including total, respiratory, and cardiovascular mortality, as well as total and respiratory hospitalization rates.

Material and methods:
The ecological study included data on the use of household coal and firewood in 139 counties obtained from the 2015 Chilean National Socio-economic Characterization Survey. Total, respiratory, and cardiovascular mortality, as well as total and respiratory hospitalization rates, were obtained from the Department of Health Statistics. Poisson models with robust error variance, Pearson linear correlation coefficients, and scatterplots were used to explore associations between household coal and firewood use and morbidity-mortality, stratifying by geographic zone.

Results:
Total, respiratory, and cardiovascular mortality and total and respiratory hospitalization rates were 5.7 per 1,000, 552 per 100,000, 157 per 100,000, 92.5 per 1000, and 8.8 per 1000 inhabitants, respectively. The median prevalence of coal use for residential cooking, heating, or water heating was 3.64%, while the median prevalence of firewood combustion was 12%. In southern counties, age- and gender-adjusted respiratory mortality increased 2.02 (95% CI: 1.17–3.50), 1.5 (95% CI: 1.11–1.89), and 1.76-fold (95% CI: 1.19–2.60) for each percentage increase in household coal and firewood use for heating, cooking and heating water, respectively.

Conclusions:
The prevalence of household coal and firewood used for heating and cooking was positively correlated with respiratory mortality and hospitalization in southern zone counties.