Mineral aerosol in the atmosphere is a major part of the Earth’s aerosol budget. Organic films on these aerosols affect the aerosol’s ability to promote cloud formation and alter its optical properties. Chemical oxidation of this film will cause changes in cloud formation and atmospheric light scattering – both effects in modern climate change. Using neutron reflection to record (1) the oxidation kinetics of a bilayer on a quartz substrate as a proxy for these organic films will allow the atmospheric lifetime to be estimated (and compared to a typical mineral aerosol lifetime of 10 days) and (2) the change in film thickness during oxidation to allow the optical properties of such an aerosol to be calculated with Mie scattering. The oxidant will be the prevalent ozone molecule, contained in cloud water. Its reactivity will be compared to that of OH radicals from recent work.