Short Term Seasonal Effect of Ambient Air Pollutants and Airborne Fungal Spores on the Lung Function of School Children in Western Cape, South Africa: A Panel Study

摘要

Background: Only 3 previous epidemiological studies have investigated the combined effect of short-term ambient air pollutants and fungal spores on individual level children's lung function. These studies did not investigate respiratory effects beyond 1-day lag nor investigated interaction effects. We aimed at investigating the combined effect of short-term air pollutant and fungal spore exposure on individual level lung function of school children. Methods: A panel study was conducted incorporating testing for 2 consecutive school-weeks each in summer and winter on 553 grade-4 school children from 4 informal settlements in the Western Cape Province of South Africa. Outcomes were measured using peak flow meters obtained 3-times daily concurrently at all schools. Daily PM10 levels was available from a stationary monitor near 2 of the study areas, while daily levels of fungal spores was measured using spore traps in all 4 study areas throughout the year. The effects were analysed using single- and multi-pollutant distributed lag linear and non-linear model for lags up to 5-days. Results: Daily Alternaria and Cladosporium was significantly associated with FEV1 deficit and increased PEF intraday variability, especially in winter. The strongest adverse effect was on FEV1 (-369.34 ml, 95% CI: -650 to -87.77 ml) resulting from an overall cumulative increase of 50 spores/m3 in Cladosporium from lag day-0 through lag day-5. There was significant interaction between PM10 and Alternaria on reduced FEV1 (p < 0.001) and increased intraday-variability in PEF (p < 0.001), including PM10 - Cladosporium interaction on increased intraday variability in PEF (p < 0.01), all during winter. Conclusion:The study provides evidence that daily exposure to ambient fungal spores, Alternaria and Cladosporium results in lung function deficits especially in winter. The adverse effect on lung function by the fungal spores can occur beyond the day of exposure and is modified by ambient PM10 exposure.