Childhood Air Pollution Exposure Associated with Self-reported Bronchitic Symptoms in Adulthood

Abstract

Rationale: Few studies have examined the effects of long-term childhood air pollution exposure on adult respiratory health, including whether childhood respiratory effects underlie this relation. Objectives: To evaluate associations between childhood air pollution exposure and self-reported adult bronchitic symptoms while considering child respiratory health in the Southern California Children's Health Study. Methods: Exposures to nitrogen dioxide (NO₂), ozone, and particulate matter <2.5 μm and <10 μm in diameter (PM₁₀) assessed using inverse-distance-squared spatial interpolation based on childhood (birth to age 17 yr) residential histories. Bronchitic symptoms (bronchitis, cough, or phlegm in the past 12 mo) were ascertained via a questionnaire in adulthood. Associations between mean air pollution exposure across childhood and self-reported adult bronchitic symptoms were estimated using logistic regression. We further adjusted for childhood bronchitic symptoms and asthma to understand whether associations operated beyond childhood respiratory health impacts. Effect modification was assessed for family history of asthma, childhood asthma, and adult allergies. Measurements and Main Results: A total of 1,308 participants were included (mostly non-Hispanic White [56%] or Hispanic [32%]). At adult assessment (mean age, 32.0 yr; standard deviation [SD], 4.7), 25% reported bronchitic symptoms. Adult bronchitic symptoms were associated with NO₂ and PM₁₀ childhood exposures. Odds ratios per 1-SD increase were 1.69 (95% confidence interval, 1.14-2.49) for NO₂ (SD, 11.1 ppb) and 1.51 (95% confidence interval, 1.00-2.27) for PM₁₀ (SD, 14.2 μg/m³). Adjusting for childhood bronchitic symptoms or asthma produced similar results. NO₂ and PM₁₀ associations were modified by childhood asthma, with greater associations among asthmatic individuals. Conclusions: Childhood NO₂ and PM₁₀ exposures were associated with adult bronchitic symptoms. Associations were not explained by childhood respiratory health impacts; however, participants with childhood asthma had stronger associations.

Keywords: Air pollution; bronchitis; cough; nitrogen dioxide; particulate matter; phlegm.