Indoor solid fuel use and renal function among middle-aged and older adults: A national study in rural China

Solid fuel use is the main source of indoor air pollution, especially in rural areas of developing countries. Nevertheless, the evidence linking indoor solid fuel use and renal function is very limited. Therefore, we investigated the association between indoor solid fuel use and renal function among middle-aged and older adults in rural China. Cystatin C (CysC) concentration of each participant was used to calculate the estimated glomerular filtration rate (eGFR). We used the baseline data to investigate the associations between solid fuel use for cooking and heating and eGFR through a linear-mixed effects model. Then, we applied the generalized linear-mixed effects model with binary distribution to examine the relationship between renal function decline and cooking fuel switching from 2011 to 2015. A total of 4959 participants were included at baseline, and 3536 participants were included in the follow-up analysis. Compared to participants who used clean fuel for both cooking and heating, the eGFR was significantly lower among participants who cooked with solid fuel and heated with clean fuel (β: -2.81; 95% CI: -5.53, -0.09). In the follow-up analysis, the risks of renal function decline for participants using solid fuel for cooking were significantly higher in males (OR: 2.74; 95% CI: 1.68, 4.49), smokers (OR: 5.70; 95% CI: 2.82, 11.55), and drinkers (OR: 7.11; 95% CI: 3.15, 16.02) compared to females, non-smokers, and non-drinkers. Moreover, 45-65 years aged participants (OR: 0.54; 95% CI: 0.33, 0.89) and non-drinkers (OR: 0.61; 95% CI: 0.41, 0.92) who switched from solid to clean cooking fuel had a lower risk of renal function decline. In conclusion, our findings show that household solid fuel use is likely to be an important risk factor for renal function decline in rural China. And switching to cleaner fuel may provide significant public health benefits.