Airborne contaminants of the gaseous type can affect all three components of photographic materials: final image material, binder, and support. While color dye images seem relatively less affected, silver images can become faded, discolored, and mirrored from exposure to oxidizing or reducing gases such as ozone, nitrogen oxides, and hydrogen sulfide. Silver image deterioration is a process of oxidation/migration/reduction which can be influenced at any point by atmospheric contaminants, or those which originate from storage containers. Gelatin binders act as a barrier to atmospheric gasses at low RH, but not at high RH. Cellulosic supports for paper prints or cellulose nitrate and acetate films are subject to acid hydrolysis. Absorption of acids from the atmosphere can initiate catastrophic degradation in cellulostic plastics. The objectives and apparatus of a large research program now underway at the Image Permanence Institute on the effects of air pollution on microfilm are given.