This work aims at providing a fundamental description of the aluminum combustion process in SRM representative gases, focusing on the phenomenology of a burning droplet reacting in pure CO2 and CO by varying pressure. Using an electrostatic levitator, single micron-sized aluminum particles are isolated in a static gaseous environment to observe their self-sustained combustion with optical diagnostics. Combustion occurs in a diffusion mode in CO2 and is limited to surface reactions in CO but, in each case, the combustion process seems driven by some condensed compounds accumulation on the droplet surface during reaction and modulated by the pressure.