Fig. 2: Year-round variation of PM2.5, BC, and source-diagnostic ratios.
From: Black carbon emissions from traffic contribute substantially to air pollution in Nairobi, Kenya
a Shows PM2.5 and BC concentrations, b shows OC/BC and BC/PM2.5 ratios, c shows SO42−/BC and NH4+/BC ratios and d presents K+/BC and NO3−/BC ratios. The predominant air masses arriving at Nairobi are marked out on top, and the transition periods are highlighted in light brown colour.
