Antenatal ambient pollution and impulse oscillometry in children from the Mother and Child in the Environment (MACE) birth cohort, Durban, South Africa

<bold>Aim:</bold> Ambient pollutant-related large airways disorders may arise pre-clinically through impacts on the distal airways. Our aim was to determine whether antenatal exposure to ambient pollutants is associated with impulse oscillometry (IOS) measures in schoolchildren. <bold>Methods:</bold> Pregnant females, recruited at public antenatal clinics in the first trimester from low-socioeconomic communities in Durban, South Africa, were followed-up until delivery. Newborns were followed up in infancy and annually. To date, 312 children have performed IOS, clinical assessments and interviews. Hybrid land-use regression and dispersion modelling provided household level exposure. Exposure metrics included averages for pregnancy year, first trimester and birth month for particulate matter (10 and 2.5 microns (PM₁₀, PM_2.5), nitrogen dioxide and sulphur dioxide (SO₂). <bold>Results:</bold> Median (ug/m³) (range) of the pollutants were: NO₂: 15.9 (7.54-25.9); PM₁₀: 30.5 (3.8-57.9); PM_2.5: 13.3 (9.02-14.1) and SO₂: 3.3 (2.1-5.8). The mean age was 7.4 years (sd=1.4), with 50.3% females. Asthma compatible features were present in 13.8%. Median (cmH₂O/L) (interquartile range) of the IOS measures were: Rx_5-20: 2.5 (−2.8-7.4); Ax: 41.6 (0.9-114.6); X₅ z-score: 0.65 (−3.9-4.3) and R₅ z-score: 0.27 (−2.3-2.9). Although showing an increase in resistance and decline in reactance, pollutant metrics did not generally reach statistical significance, expect for annual SO2 (with X5 z-score), and annual PM₁₀ and PM_2.5 (with frequency response). <bold>Conclusion:</bold> Preliminary findings suggest that associations between air pollution and responses of the distal airways among children may be present.