The Legacy of Colonial‐Era Urban Planning on Present Day Air Quality Disparities in Kampala, Uganda

British colonial urban planners in Kampala, Uganda, designed segregated neighborhoods for Europeans, Asians, and Africans, under the colonial public health guidance. No studies have investigated how these historical urban design decisions relate to modern air pollution exposure disparities in African cities. We sought to determine whether colonial‐era racial segregation of settlements in Kampala, Uganda, influences modern intra‐urban spatial distribution of ambient fine particulate matter (PM 2.5 ) concentrations in the city. Using an urban network of 52 low‐cost PM sensors, we estimated monthly PM 2.5 concentrations across Kampala from 2021 to 2022. We manually digitized and correlated 2020 satellite imagery and street maps of the three historical boundaries of European/Asian and African settlements from a 1951 map. Extreme gradient boosting trees, random forest models, and empirical Bayes kriging were used to predict gridded monthly PM 2.5 averages for the study area. We used non‐parametric statistical tests and multivariable linear regression to compare monthly PM 2.5 levels between European/Asian and African settlements. We observed significantly higher median monthly PM 2.5 concentration in African settlements (median = 33.0 μg/m 3 [interquartile range = 28.2, 39.3]) compared to European/Asian areas (median = 28.8 μg/m 3 [IQR = 25.2, 33.5]). In crude linear regression models, African settlements had a higher PM 2.5 concentration by 9.2% (95% CI: 6.4, 18.5). African settlements showed greater seasonal PM 2.5 variations and higher current social vulnerability. This study highlights the enduring influence of colonial urban planning on today's environmental health inequalities.