Abstract
Background: A growing body of evidence supports an association between air pollution exposure and adverse mental health outcomes, especially in adulthood however, very little is known about the effects of early life air pollution exposure during childhood with existing evidence at risk of unmeasured and residual confounding. We examined longitudinal associations between the extent and timing of children’s annual air pollution exposure from conception to age 10 years and a wide range of cognitive, educational and mental health outcomes in childhood and adolescence that were assessed prospectively as part of a large birth cohort study.
Methods: We linked historical air pollution data (μg.m-3) from pregnancy to age 10 years (1976–1987) using the addresses of all cohort members (n=1,265) of the Christchurch Health and Development Study (CHDS) who were born in New Zealand in mid-1977. Latent Class Growth Mixture Models were used to characterise different trajectories of air pollution exposure from the prenatal period to age 10 years. We then examined associations between these air pollution exposure trajectories and 16 outcomes in childhood and adolescence using R Studio and Stata V18.
Results: Four air pollution exposure trajectories were identified: i) low, ii) persistently high, iii) high prenatal and postnatal, and iv) elevated pre-school exposure. While some associations were attenuated, after adjusting for a variety of covariates spanning childhood, family sociodemographic background and family functioning characteristics, several associations remained. Relative to the lowest exposure trajectory, persistently high and high prenatal and postnatal exposure were both related to attentional problems. High prenatal and postnatal was also related to higher risk of substance abuse. Elevated pre-school exposure was associated with conduct problems, lower educational attainment and substance abuse and persistently high childhood exposure increased risk of substance abuse.
Conclusion: It is important to interpret the small effects in our study in the light of individual- versus population-level effects. For instance, 10-year exposure to air pollution may explain little of an individual’s risk of mental health outcomes developing however, it may help to explain the shift in population-level outcomes which have gradually shifted upwards with the likelihood of increased burden of disease over time. Our study highlights potential adverse and longer-term impacts of air pollution exposure during childhood on subsequent development in later life.
Oral presentation