Indoor air pollutants and respiratory symptoms among residents of an informal urban settlement in Uganda: A cross-sectional study

by Solomon T. Wafula, Aisha Nalugya, Hilbert Mendoza, Winnifred K. Kansiime, Tonny Ssekamatte, Abel W. Walekhwa, Richard K. Mugambe, Florian Walter, John C. Ssempebwa, David Musoke

Indoor air pollutants (IAP) and household conditions such as dampness, crowding and chemical exposures have been associated with acute and chronic respiratory infections. In Uganda, literature on the effects of IAP on respiratory outcomes in informal settlements is limited.

We describe the baseline household characteristics of 284 adults and their children in an informal settlement in Uganda from April to May 2022. We monitored same-day indoor concentrations of particulate matter PM_2.5, PM₁₀, Carbon monoxide (CO), relative humidity %, and temperature from 9 am to 2 pm and interviewed caregivers/mothers about their respiratory symptoms and those of their children in the previous 30 days. We employed robust Poisson regressions to evaluate the associations between indoor air indicators and respiratory health symptoms.

Approximately 94.7% of households primarily used biomass fuels and 32.7% cooked from inside their dwelling rooms. The median PM_2.5, PM₁₀ and CO levels were 49.5 (Interquartile range (IQR) = 31.1,86.2) μg/m³, 73.6 (IQR = 47.3,130.5) μg/m³ and 7.70 (IQR = 4.1,12.5) ppm respectively. Among adults, a 10 unit increase in PM_2.5 was associated with cough (Prevalence Ratio (PR) = 3.75, 95%CI 1.15–1.55). Dwelling unit dampness was associated with phlegm (PR = 2.53, 95%CI = 1.39–4.61) and shortness of breath (PR = 1.78, 95% CI 1.23–2.54) while cooking from outside the house was protective against shortness of breath (PR = 0.62, 95% CI = 0.44–0.87). In children, dampness was associated with phlegm (PR = 13.87, 95% CI 3.16–60.91) and cough (PR = 1.62, 95% CI 1.12–2.34) while indoor residual spraying was associated with phlegm (PR = 3.36, 95%CI 1.71–6.61).

Poor indoor air conditions were associated with respiratory symptoms in adults and children. Efforts to address indoor air pollution should be made to protect adults and children from adverse health effects.