No, a high quality aluminum foil insulation products reflectivity is NOT AFFECTED by the natural oxidation process.All aluminum surfaces oxidize when exposed to oxygen and this oxidation process produces a CLEAR layer over the top of the surface of aluminum. This clear layer will increase in thickness to a point where the oxygen in the environment can no longer continue the oxidation process.High quality aluminum foil insulation products, such as our RadiantGUARD Ultima-foil do not lose reflectivity because there is a significant amount of aluminum remaining after the completion of the oxidation process.For detailed information on the research and findings on the oxidation of aluminum insulation, please visit this radiant barrier oxidation technical study.