Towards healthy sleep environments: Ambient, indoor, and personal exposure to PM and its implications in children's sleep health.

The growing impact of climate change and escalating wildfire seasons has led to heightened ambient air pollution, potentially affecting children's sleep health. However, current epidemiological research often relies on outdoor weather data to model the environmental impacts on sleep health, potentially mischaracterizing the actual bedroom environment. To address these challenges, we conducted experiments to investigate the relationships among ambient, indoor, and personal exposure to PM concentrations and obstructive sleep apnea (OSA) in children. We employed computational fluid dynamics (CFD) simulations to assess how personal exposures are influenced by factors such as air distribution design, supply air temperature (T), body shape, and sleep position. Our statistical analysis revealed notable associations between OSA severity as measured by obstructive apnea-hypopnea index (OAHI) and indoor PM concentrations (β: 11.52; 95% CI: 5.07 to 17.96; p < 0.01) and personal PM exposures (β: 18.92; 95% CI: 9.80 to 28.04; p < 0.001), with personal exposure demonstrating a stronger relationship. Our findings highlighted the critical role of T and body shape in exacerbating personal exposure, as they could modify the bedding microenvironment around children's breathing zone during sleep. We assessed the effect of air filtration interventions on mitigating personal PM exposure and modulating OSA severity in children. Higher air filter efficiencies such as MERV14 or above can modulate severe OSA for more than 80% of the year. However, during wildfire episodes, because air filtration interventions alone may be insufficient, comprehensive strategies, including the potential use of air cleaners and personal protective equipment (PPE), are necessary to ensure children's health. Our research demonstrated that quantifying personal exposure is a more informative predictor than solely relying on ambient or indoor measures for estimating OSA in children.