Several researchers have also pointed out that biomass burning is a major contributor to regional pollution in Africa. One of the methods used to identify regional pollution is the vertical profiling of ozone using aircraft campaigns. Some of these studies in equatorial Africa include MOZAIC 1997-2003 and the INDOEX ex- periment focused on pollution outflow from India over the Indian Ocean and towards eastern Africa during win- ter monsoon conditions [15]. In other tropical and southern African regions, several field campaigns have been conducted. These include TRACE-A 1992 [16], SAFARI 1992, and SAFARI 2000. However, as Thompson et al. argue, weekly observations of O3 may not be robust enough for trend analysis in the trop- ics due to strong variability caused by deep convection.