Landscape fire-sourced PM_2.5 and kidney function in children: evidence from a national cross-sectional study in China

Landscape fire-sourced fine particulate matter with an aerodynamic diameter ≤2.5 μm (PM_2.5) may be more oxidatively active and biologically toxic than PM_2.5 from other sources, but evidence of its kidney effects in children is limited.

To examine the association between landscape fire-sourced PM_2.5 exposure and estimated glomerular filtration rate (eGFR) in children and identify potentially susceptible subgroups.

This cross-sectional study included 12,102 children aged 5-18 years who participated in the China National Nutrition and Health Surveillance of Children and Lactating Women between October 2016 and December 2018. eGFR was estimated from serum creatinine (Scr), and three-year average pre-survey exposure to landscape fire-sourced PM_2.5 was assigned using school addresses. Associations were estimated using linear mixed-effects models, with subgroup analyses by sex, obesity, NDVI, and nutrient intake.

The mean age was 10.90 ± 3.12 years, and 6,064 participants (50.11%) were boys. Each IQR (0.505 μg/m³) increase in landscape fire-sourced PM_2.5 was associated with a 0.83 mL/min/1.73 m² reduction in eGFR (95% CI: -1.03, -0.62). The association was stronger among middle school students (β = -1.46 mL/min/1.73 m²; 95% CI: -1.83, -1.09) than among primary school students (β = -0.59 mL/min/1.73 m²; 95% CI: -0.84, -0.34; P_{for difference} < 0.001). Stratified analyses showed significant between-group differences by NDVI, vitamin intake, and carbohydrate intake, with stronger inverse associations in the lower-NDVI and lower-intake groups (P_{for difference} < 0.05 for all reported comparisons).

Landscape fire-sourced PM_2.5 exposure was associated with lower eGFR in the overall population, with stronger associations among middle school students and children with lower NDVI or lower vitamin or carbohydrate intake.