Association of joint exposure to PM2.5 and O3 with renal dysfunction in rural residents: Mediation of blood lipid levels.

Emerging evidence suggests that fine particulate matter (PM2.5) and ozone (O3) may exert detrimental effects on renal function. However, the impact of short-term joint exposure and underlying mechanisms remain unclear. This study aimed to examine the joint effect of short-term exposure to PM2.5 and O3, along with the possible mediating role of blood lipids in the association between PM2.5 or O3 and renal function. Data were obtained from 3894 participants in the Prospective Cohort Study on the Common Chronic Non-Communicable Diseases in Rural areas of Henan Province, China. Short-term exposure to O3 and PM2.5 was assessed using environmental monitoring data, and renal function was evaluated using estimated glomerular filtration rate (eGFR). Linear mixed-effects models were employed to assess associations, and stratified analyses were conducted to examine potential effect modifiers such as relative humidity and income. Mediation analyses were conducted to evaluate the role of blood lipids. It was shown that a significant decline in eGFR was associated with an 1 µg/m³ increase in PM2.5 or O3. The participants exposed to High PM2.5+High O3 environment exhibited the greatest reduction in eGFR compared to those exposed to Low PM2.5+Low O3 (β= -5.12; 95 % CI: -6.46, -3.77). Mediation analyses revealed that the proportion of the effect mediated by total cholesterol (TC) was 6.4 % for PM2.5 and 13.6 % for O3 in their associations with eGFR (P < 0.05). However, no such associations were detected for high-density lipoprotein cholesterol (HDL-C), triglyceride (TG) and low-density lipoprotein cholesterol (LDL-C). Lower eGFR was detected among rural residents following short-term exposure to PM2.5 and O3. These findings were more significant with higher joint exposures, indicating that joint exposure to PM2.5 and O3 is associated with the decline in eGFR, which is partly mediated by blood lipids.