Background: The developing lung is highly susceptible to environmental toxicants, with both short- and long-term exposure to ambient air pollutants linked to early childhood effects. This study assessed the short-term exposure effects of nitrogen dioxide (NO 2 ) and particulate matter (PM 10 ) on lung function in infants aged 6 weeks, 6, 12 and 24 months, the early developmental phase of child growth.
Methods: Lung function was determined by multiple breath washout and tidal breathing measurement in non-sedated infants. Individual exposure to NO 2 and PM 10 was determined by hybrid land use regression and dispersion modelling, with two-week average estimates (preceding the test date). Linear mixed models were used to adjust for the repeated measures design and an age*exposure interaction was introduced to obtain effect estimates for each age group.
Results: There were 165 infants that had lung function testing, with 82 of them having more than one test occasion. Exposure to PM 10 (μg/m 3 ) resulted in a decline in tidal volume at 6 weeks [-0.4 ml (-0.9; 0.0), p = 0.065], 6 months [-0.5 ml (-1.0; 0.0), p = 0.046] and 12 months [-0.3 ml (-0.7; 0.0), p = 0.045]. PM 10 was related to an increase in respiratory rate and minute ventilation, while a decline was observed for functional residual capacity for the same age groups, though not statistically significant for these outcomes. Such associations were however less evident for exposure to NO 2 , with inconsistent changes observed across measurement parameters and age groups.
Conclusion: Our study suggests that PM 10 results in acute lung function impairments among infants from a low-socioeconomic setting, while the association with NO 2 is less convincing.
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