Background Acute pollutant-related lung function changes among children varies across pollutants and lag periods. We examined whether short-term air pollutant fluctuations were related to daily lung function among a panel of children and whether these effects are modified by airway hyperresponsiveness, location and asthma severity.
Methods Students from randomly selected grade 4 classrooms at seven primary schools in Durban, participated, together with asthmatic children from grades 3–6 (n=423). The schools were from high pollutant exposed communities (south) and compared with schools from communities with lower levels of pollution (north), with similar socioeconomic profiles. Interviews, spirometry and methacholine challenge testing were conducted. Bihourly lung function measurements were performed over a 3-week period in four phases. During all schooldays, students blew into their personal digital monitors every 1.5–2 hours. Nitrogen dioxide (NO2), nitrogen oxide (NO), sulphur dioxide and particulate matter (<10 μm diameter) (PM10) were measured at each school. Generalised estimating equations assessed lag effects, using single-pollutant (single or distributed lags) models.
Results FEV1 declines ranged from 13 to 18 mL per unit increase in IQR for NO and 14–23 mL for NO2. Among the 5-day average models, a 20 mL and 30 mL greater drop in FEV1 per IQR for NO2 and NO, respectively, among those with airway hyperresponsiveness compared with those without. Effects were seen among those with normal airways.
Conclusions This first panel study in sub-Saharan Africa, showed significant declines in lung function, in response to NO and NO2 with effects modified by airway hyperresponsiveness or persistent asthma.
- paediatric asthma
- asthma epidemiology
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Contributors RNN, SB and TR chiefly responsible for concept and design. RNN contributed to acquisition. GM chiefly responsible for analysis. Drafting the work was done primarily by GM and RNN, while SB and TR were involved in revising it critically for important intellectual content. All authors contributed to the interpretation of the data, final approval of the version published and agreed to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.
Funding This project was supported by grants from the eThekwini Municipality, the South African Medical Research Council, and the US National Institutes of Health/Fogarty International Center (grant D43 TW000812). The funders played no role in the study design, collection, analysis or interpretation of the data, the writing of the reports or the decision to submit for publication.
Competing interests None declared.
Patient consent for publication Not required.
Ethics approval Ethical approval was obtained from the Institutional Review Board of the University of Michigan and the Biomedical Research Ethics Committee of the University of KwaZulu-Natal.
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement No data are available.
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