Based on 3-dimentional CALIPSO VFM data, we documented the seasonal means and seasonal cycle of the vertical profiles of mineral dust, biomass burning smoke, and polluted dust (external mixture of dust and smoke), their emissions sources and transport pathways over Africa and the tropical Atlantic Ocean. The ITCZ plays a role regulating the aerosol distribution. Dust from the north and smoke from the south tend to be washed out by the rain in the ITCZ, limiting their meridional spread across the ITCZ, and hence the ITCZ as a barrier. But, dust and smoke can occasionally be transported across the ITCZ by the shallow meridional circulation with low-level northerlies and mid-level southerlies, and thus the ITCZ is a leaky barrier. In consequence, pure dust is rare south of the ITCZ and pure smoke rare north of it, but there are always mixed dust and smoke (polluted dust) on both sides of the ITCZ.