Lagged acute respiratory outcomes among children related to ambient pollutant exposure in a high exposure setting in South Africa.

Acute ambient air pollution impacts on the respiratory health of children may be lagged across time. We determined the short-term lagged effects of particulate matter (PM _2.5 ), sulphur dioxide (SO ₂ ), and oxides of nitrogen (NO _x ) on the respiratory health of children living in low-income communities.
Methods: A school-based study was conducted using a repeated measures design, across summer and winter, in four schools in each of four suburbs in the Vaal Triangle, South Africa. Data for PM _2.5 , NO _x , and SO ₂ were obtained from monitoring stations within close proximity of the schools. Over 10 school days in each phase, grade 4 children completed a symptoms log and lung function tests. Parents completed a child respiratory questionnaire. Generalized estimation equations models adjusted for covariates of interest in relation to lung function outcomes and air pollutants including lag effects of 1-5 days.
Results: Daily PM _2.5 , NO _x , and SO ₂ median concentration levels were frequently higher than international standards. Among the 280 child participants (mean age 9 years), the prevalence of symptoms based on probable asthma was 9.6%. There was a consistent increased pollutant-related risk for respiratory symptoms, except for NO _x and shortness of breath. Lung function, associated with pollutant fluctuations across the different lags, was most pronounced for peak expiratory flow rate (PEFR) for PM _2.5 and SO ₂ . A preceding 5-day average SO ₂ exposure had the largest loss (7.5 L/minute) in PEFR.
Conclusions: Lagged declines in daily lung function and increased odds of having respiratory symptoms were related to increases in PM _2.5 and SO ₂ among a school-based sample of children.
Competing Interests: The authors declare that they have no conflicts of interest with regard to the content of this report. Sponsorships or competing interests that may be relevant to content are disclosed at the end of the article.
(Copyright © 2022 The Authors. Published by Wolters Kluwer Health, Inc. on behalf of The Environmental Epidemiology. All rights reserved.)