Early-Life Exposure to Ambient Air Quality and Infant Health-Related Quality of Life: A Longitudinal Multi-Center Cohort in China

Air pollution poses a major public health threat, yet longitudinal evidence on its impact on infant health-related quality of life (HRQoL) remains limited. This study investigated the longitudinal associations between early-life exposure to outdoor air pollution and infant HRQoL, focusing on psychological and physiological domains. Between November 2021 and September 2022, 779 mother–newborn pairs were recruited, with 696 completing follow-up at 12 months. HRQoL was assessed at 1, 4, 6, and 12 months using the Pediatric Quality of Life Inventory™, and exposures to PM2.5, PM10, NO2, and SO2 were analyzed using linear mixed-effects models adjusted for infant sex, household income, sibling status, and other covariates. Higher concentrations of all pollutants were associated with lower total HRQoL scores. Stratified analyses showed that PM2.5, PM10, and SO2, but not NO2, were associated with steeper age-related declines in total scores. Inverse associations with psychosocial health were consistent across pollutants, with pronounced age-related declines in high-exposure groups; for physical health, only SO2 and NO2 remained significant after adjustment, with modest age-related changes. These findings suggest that early-life air pollution exposure is associated with smaller gains in HRQoL during infancy, particularly in psychosocial well-being, highlighting the importance of improving air quality to support early development.