Respiratory protective devices such as National Institute for Occupational Safety and Health (NIOSH) certified disposable filtering facepiece respirators (FFRs) are often recommended for use by healthcare workers and the general public for infection control. However, during a wide-scale breakout of a disease spread by human-to-human transmission via infectious aerosol, shortages of FFRs are likely. One possible solution to the potential shortage is to reuse the FFR after decontamination to remove any infectious material. However, little data exists on the effects of various decontamination methods. In this study, two models of FFRs (one N95 and one P100) were treated with ten decontamination processes at two conditions each. Filtration performance of the treated respirators plus two controls was assessed using a poly-dispersed sodium chloride aerosol test method similar to that used by the NIOSH for respirator certification. Decontamination using an autoclave, 160º C dry heat, 70% isopropyl alcohol, and soap and water (20 minute soak) caused significant filter degradation to both N95 and P100 FFRs. The particle penetration levels were greater than allowed for NIOSH certification. Filtration performance after decontamination using bleach, ethylene oxide, and a microwave oven was degraded for both respirator models, although particle penetration levels were still less than the NIOSH certification criteria. The decontamination methods that had the least effect on particle penetration involved hydrogen peroxide (vaporized and liquid forms) and UV radiation. Future research should consider low-temperature decontamination methods such as vaporized and liquid hydrogen peroxide, ethylene oxide, microwave radiation for 2 minutes or less, UV radiation, and 10% diluted household bleach for further study.