Exposure to vehicle traffic during childhood and lung function development in young adulthood - a 10-year prospective study

<bold>Background:</bold> Exposure to high levels of traffic-related air pollution during childhood is associated with reduced lung function, but it is not clear if exposure to relatively low levels during childhood has effects on lung function in young adulthood. <bold>Aim:</bold> To study how exposure to vehicle traffic during childhood associate with lung function in young adults in a 10-year follow-up of a population-based cohort in Northern Sweden. <bold>Methods:</bold> The OLIN pediatric cohort II was recruited in 2006 at age 8y and exposure to vehicle traffic at baseline was studied in relation to lung function at follow-up in 2016-2017 (n=1056 participants). Exposure was defined based on proximity (within a 200 m radius from the home address) to a road with a minimum daily count of heavy vehicles (≥250 and ≥500) or for any type of vehicle (≥4000 and ≥8000). Those below these thresholds were considered unexposed. The association between exposure at baseline and lung function at follow-up was analyzed by linear regression adjusting for confounders. <bold>Results:</bold> In general, those exposed had lower FEV1 and FVC than unexposed, but not significantly so in all comparisons. Those exposed to ≥250 heavy vehicles/day had a lower FEV1% of predicted at follow-up (95.5%) compared with unexposed individuals (97.4%), p=0.034, and this association remained significant after adjustment (p=0.035). Also, individuals exposed to ≥8000 vehicles/day had a lower FVC% of predicted (97.8%) than those unexposed (99.9%), p=0.046, with p=0.051 after adjustment. <bold>Conclusions:</bold> Exposure to relatively low levels of vehicle traffic during childhood may be associated with a slight reduction in lung function during young adulthood.