Combined effects of traffic-related air pollution, climate factors, and greenness on respiratory disease risk in infants

Prenatal exposure to climate factors, air pollution, and green space has been linked to respiratory diseases in infants. However, the role of the combined effects of exposure to these factors on respiratory ailments remains unclear. Here we investigate the association of combined exposure to traffic-related air pollution (TRAP), climate factors, and green space during the prenatal period with respiratory diseases in infants. We enrolled 454 participants from the ongoing prospective birth cohort known as the Mothers and Children’s Environmental Health study. Data on infant respiratory diseases were collected from parents or guardians. Average exposure values of TRAP, climate factors, and green spaces for the study population were calculated based on geocoded residential addresses. Multiple logistic regression and quantile-based g-calculation models were utilized to examine the association of exposure to environmental factors and green space with respiratory diseases. The combined exposure to climate factors and TRAP during the first trimester of pregnancy was associated with an increased risk of respiratory diseases in infants. High levels of particulate matter with a diameter less than 2.5 μm (PM_2.5) and temperature increased the risk of respiratory diseases (adjusted odds ratio (AOR): 1.615, 95% confidence interval (CI): 1.001, 2.658). Additionally, the risk of respiratory diseases from exposure to air pollution and temperature was associated with lower tertiles of residential green spaces. The AOR was 1.064 (95% CI: 1.001, 1.133) per 1 µg/m³ increase in PM_2.5, 1.057 (95% CI: 1.001, 1.116) per 1 ppb increase in NO₂, and 1.108 (95% CI: 1.001, 1.176) per 1 ℃ increase in temperature. Incorporating green space into the analysis of joint exposure to climate factors and air pollution reduced the risk of respiratory disease. This study proposes that combined exposures to climate factors, TRAP, and green spaces during pregnancy are associated with infant respiratory diseases. Fewer residential green spaces could enhance the association of climate factors and air pollution with respiratory diseases.