The oxidative potential of PM_2.5 outperforms its mass concentration in association with childhood sleep disorders: Evidence from a large-scale study in China

Existing studies have shown that PM_2.5 mass concentration (PMC) is associated with sleep disorders in children, and the oxidative potential of PM_2.5 (OPP) has been recognized as a relevant indicator of health risks. However, its associations with childhood sleep disorders remains unclear. We investigated the associations of PMC and OPP with sleep disorders in 131,412 children aged 6-18 years recruited from Guangdong Province, China, in 2018, using a generalized linear regression model. We found that both PMC and OPP were significantly associated with higher odds of sleep disorders in children, with OPP showing a stronger association than PMC. For each interquartile range (IQR) increase in DTTm (normalized to PM mass) and DTTv (normalized to air volume), the adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for global sleep disorder were 1.252 (1.226, 1.279) and 1.202 (1.169, 1.235), respectively. Both were higher than that of PMC: 1.132 (1.079, 1.187). Similar patterns were observed for sleep disorder scores, the adjusted regression coefficients (β) and 95% CIs of global sleep disorder scores for DTTm, DTTv and PMC were 1.452 (1.400, 1.504), 0.936 (0.871, 1.000) and 0.752 (0.652, 0.852), respectively. Furthermore, the observed associations of OPP with sleep disorders were pronounced among boys, non-breastfed children, those aged >12 years, and those born at term. Our findings provide large-scale evidence that OPP may better capture the associations between PM_2.5 and childhood sleep health than PMC, supporting the use of OPP as a meaningful exposure metric in air pollution epidemiology.