biodegradation process is cited as taking as little as one month to as long as 15 years or more, depending on the environmental conditions. The major factor that affects the biodegradation duration is the availability of acetylesterase and cellulase enzymes. Without these enzymes, biodegradation only occurs through chemical hydrolysis and stops there. Temperature is another major factor, if the organisms that contain the enzymes are too cold to grow, then biodegradation is severely hindered. Availability of oxygen in the environment also affects the degradation. Cellulose acetate is degraded within 2–3 weeks under aerobic assay systems of in vitro enrichment cultivation techniques and an activated sludge wastewater treatment system. It is degraded within 14 weeks under anaerobic conditions of incubation with special cultures of fungi. Ideal conditions were used for the degradation (i.e. right temperature, and available organisms to provide the enzymes). Thus, filters last longer in places with low oxygen concentration (ex. swamps and bogs). Overall, the biodegraditon process of cellulose acetate is not an instantaneous process. Photodegradation The other process of degradation is photodegradation, which is when a molecular bond is broken by the absorption of photon radiation (i.e. light). Due to cellulose acetate carbonyl groups, the molecule naturally absorbs light at 260 nm, but it contains some impurities which can absorb light. These impurities are known to absorb light in the far UV light region (< 280 nm). The atmosphere filters radiation from the sun and allows radiation of > 300 nm only to reach the surface. Thus, the primary photodegradation of cellulose acetate is considered insignificant to the total degradation process, since cellulose acetate and its impurities absorb light at shorter wavelengths. Research is focused on the secondary mechanisms of photodegradation of cellulose acetate to help make up for some of the limitations of biodegradation. The secondary mechanisms would be the addition of a compound to the filters that would be able to absorb natural light and use it to start the degradation process. The main two areas of research are in photocatalytic oxidation and photosensitized degradation. Photocatalytic oxidation uses a species that absorbs radiation and creates hydroxyl radicals that react with the filters and start the breakdown. Photosensitized degradation, though, uses a species that absorbs radiation and transfers the energy to the cellulose acetate to start the degradation process. Both processes use other species that absorbed light > 300 nm to start the degradation of cellulose