Impact of close-proximity air pollution on lung function in schoolchildren in the French West Indies

BACKGROUND High levels of asthma prevalence and severity of respiratory symptoms have been found in the Caribbean but little is known about the impact of air pollution in these regions. This study aimed to describe air pollution and measure the associations with child lung function in Guadeloupe (French West Indies). METHODS Data from 30 randomly chosen elementary schools (8-13 years old) were obtained using a standardized protocol adapted from the ISAAC2 study. We considered two health outcomes: peak expiratory flow (PEF) before running and the variation in peak expiratory flow (ΔPEF) after running. The associations between pollutants and outcomes were investigated using several air pollution exposure models: i) medium-term exposure to close-proximity pollution both indoor and outdoor for ozone (O₃) and nitrogen dioxide (NO₂) and ii) short- and medium-term exposure to background pollution for O₃, NO₂, sulphur dioxide (SO₂) and small particulate matter (PM10). RESULTS Of 1,463 children, 277 (16%) were found to have asthma. A 1-μg/m3 increase in medium-term exposure to outdoor close-proximity pollution by O₃ was associated with a PEF decrease (β = -0.32; 95% CI: -0.61;-0.03). No association was found with NO₂ regarding close-proximity pollution. The association between medium-term exposure to background pollution and PEF decrease was stronger in asthmatic children than in non-asthmatic children for O₃. No reduction in PEF or ΔPEF was shown with NO₂, SO₂ and PM₁₀ pollutants but a significant association was found between PM₁₀ and PEF increase. CONCLUSIONS Our results suggest that O₃ could have an acute effect on child lung function in the Caribbean even at a low concentration (below the WHO guidelines). Further research in the Caribbean is needed to confirm these findings.