Black carbon emissions from traffic contribute substantially to air pollution in Nairobi, Kenya

Abstract Rapid urbanization and population growth drives increased air pollution across Sub-Saharan Africa with serious implications for human health, yet pollutant sources are poorly constrained. Here, we analyse fine particulate aerosol concentrations radiocarbon composition of black carbon over a full annual cycle in Nairobi, Kenya. We find that particle exceed the World Health Organisation’s recommended safe limit throughout year, little seasonal variability concentration or composition. Organics (49 ± 7%) water-soluble inorganic ions, dominated by sulfates (13 5%), constitute largest contributors to loadings. Unlike large cities on other continents, fraction particles is high (15 4%) suggesting prominent Nairobi. Radiocarbon-based source quantification indicates fossil fuel combustion emissions dominant year (85 3%). Taken together, this from traffic key stressor quality