Air quality and attributable mortality among city dwellers in Kampala, Uganda: results from 4 years of continuous PM2.5 concentration monitoring using BAM 1022 reference instrument.

BACKGROUND: Air pollution is a known risk factor for non-communicable diseases that causes substantial premature death globally. Rapid urban growth, burning of biomass and solid waste, unpaved sections of the road network, rising numbers of vehicles, some with highly polluting engines, contribute to the poor air quality in Kampala. OBJECTIVE: To provide evidence-based estimates of air pollution attributable mortality in Kampala city, with focus on ambient fine particulate matter (PM2.5). METHODS: We utilized a time series design and prospectively collected data on daily ambient PM2.5 concentration levels in micrograms per cubic meter (µg/m3) using a Beta Attenuation Monitor (BAM-1022) in Kampala city, Uganda. We combined the PM2.5 data with all-cause mortality data obtained from the Uganda Bureau of Statistics and the Ministry of Health in Kampala. We calculated attributable risk estimates for mortality using the WHO AirQ+ tools. RESULTS: Overall, the annual average concentration for PM2.5 for the period of 4 years, 2018-2021, was 39 µg/m3. There was seasonal variation, with the rainy season months (March-June and October-December) having lower values. PM2.5 concentrations tend to be highest in the morning (09.00 h) and in the evening (21.00 h.) likely due to increased vehicular emissions as well as the influence of weather patterns (atmospheric temperature, relative humidity and wind). Saturday has the most pollution (daily average over 4 years of 41.2 µg/m3). Regarding attributable risk, we found that of all the deaths in Kampala, 2777 (19.3%), 2136 (17.9%), 1281 (17.9%) and 1063 (19.8%) were attributable to long-term exposure to air pollution (i.e., exposure to PM2.5 concentrations above the WHO annual guideline of 5 µg/m3) from 2018 to 2021, respectively. For the 4 years and considering the WHO annual guideline as the reference, there were 7257 air pollution-related deaths in Kampala city. IMPACT: Our study is the first to estimate air pollution attributable deaths in Kampala city considering the target as the WHO annual guideline value for PM2.5 of 5 µg/m3. Our monitoring data show that fine particulate matter air pollution in Kampala is above the WHO Air Quality Guideline value, likely resulting in substantial adverse health effects and premature death. While further monitoring is necessary, there is a clear need for control measures to improve air quality in Kampala city.

Ambient air pollution is associated with vascular disease in Ugandan HIV-positive adolescents.

OBJECTIVE: In this study, we aim to investigate the relationship between particulate matter, a common proxy indicator for air pollution, and markers of inflammation, monocyte activation, and subclinical vascular disease. DESIGN: A cross-sectional study. METHODS: Adolescents with perinatally acquired HIV (PHIV) and HIV-uninfected adolescents between 10 and 18years living near Kampala, Uganda were included. Daily ambient concentrations of particulate matter (PM2.5) were measured from the Eastern Arica GEOHealth Hub. Outcome variables measured were carotid intima-media thickness (IMT), as well as plasma markers of systemic inflammation, oxidized lipids, and gut integrity. Multivariable quantile regression models were used to explore the relationship between PM2.5 and IMT. RESULTS: One hundred and nineteen participants (69 PHIV, 50 HIV-uninfected) were included. The median (Q1, Q3) age was 12.7 (11.4,14.2) years, 55% were girls. Median daily PM2.5 exposure was 29.08 µg/m3 (23.40, 41.70). There was no significant difference in exposure of PM2.5 between groups (P  = 0.073). PM2.5 significantly correlated with intestinal permeability (zonulin; r = 0.43, P < 0.001), monocyte activation (soluble CD163: r  = 0.25, P = 0.053), and IMT (r  = 0.35, P = 0.004) in PHIV but not in HIV-uninfected (P ≥ 0.05). In multivariable quantile regression, after adjusting for age, sex, poverty level, soluble CD163, and zonulin, daily PM2.5 concentrations remained associated with IMT [ß  = 0.005, 95% CI (0.0003-0.010), P = 0.037] in adolescents with PHIV. CONCLUSION: Adolescents in urban Uganda are exposed to high levels of air pollution. Both PM2.5 and HIV have independently been observed to contribute to atherosclerotic disease, and our findings suggest the combined effects of HIV and air pollution may amplify the development of cardiovascular disease.