Indoor air pollutants and respiratory outcomes among residents of an informal urban setting in Uganda: a cross-sectional study

BackgroundIndoor air pollutants (IAP) such as particulate matter (PM) and carbon monoxide (CO) are a leading cause of acute respiratory symptoms, and long-term health impacts such as respiratory diseases, heart diseases and cancers. In Uganda, literature on the effects of IAP on respiratory outcomes in informal settlements is limited. This study investigated the association of selected IAPs and cooking fuels with respiratory symptoms among children and adults. MethodsThis study was conducted among 284 households in an informal settlement in Uganda from April to May 2022. Information on indoor air conditions, fuel type and adults reported the respiratory symptoms of their children as well as their respiratory symptoms within the previous 30 days. Same-day concentrations of PM less than 2.5 m (PM2.5) and less than 10 m(PM10) in diameter were monitored from 9 am to 2 pm using Temptop M2000c 2nd edition particle sensor while CO was measured using a carbon monoxide meter. Robust Poisson regression was used to model the associations between indoor air conditions, fuel type and respiratory health outcomes. ResultsApproximately 94.7% of the households were using biomass fuels. Cough (66.2%), shortness of breath (33.5%) and phlegm (17.6%) were common respiratory symptoms in adults while in children, morning cough (80.0%), day or night cough (34.4%) and shortness of breath (26.5%) were reported. The median PM2.5, PM10 and CO levels were 49.5(IQR= 31.1, 86.2) {micro}g/m3, 73.6(IQR= 47.3,130.5) {micro}g/m3 and 7.7(IQR= 4.1,12.5) ppm respectively. Increase in humidity was associated with higher levels of PM2.5 ({beta} = 2.74, p =0.004) and PM10 ({beta}= 4.14, p =0.002) however temperature increases were associated with lower levels of PM2.5 ({beta} = -11.72, p =0.009) and PM10 ({beta}= -16.36, p =0.008) but higher CO levels ({beta}=2.24, p = 0.032). Use of less polluting fuels such as electricity and gas were associated with low levels of PM2.5 ({beta}= -31.36, 95%CI =-60.7 - -2.02) while home dampness ({beta} = 3.39, 95%CI =0.07 - 6.72) was associated with higher indoor CO levels. Dampness was associated with acute phlegm in adults (PR= 2.78, 95%CI =1.57 - 4.90) and outdoor cooking was found to be associated with lower shortness of breath risk (PR = 0.60,95%CI =0.40 - 0.91). ConclusionThe prevalence of respiratory problems among adults and children was high. Poor indoor air conditions were associated with respiratory symptoms in adults and children. Efforts should be made to protect adults and children from the adverse effects of indoor air pollution.