Field-Testing Method for Loose-Fitting Powered Air-Purifying Respirators Equipped with HEPA Filters,

Respiratory protection is a key component of the biosafety program for the Regional Biocontainment Laboratory at Duke University. Two types of loose-fitting powered air-purifying respirators (PAPRs) equipped with high-efficiency particulate air (HEPA) filters have been approved for use in the facility. Although both respirator systems were previously certified by the National Institute of Occupational Safety and Health for use in occupational environments that pose a risk of respiratory exposure to infectious agents, there are currently no regulatory requirements for routine field-testing of units in situ. This report describes a method for conducting on-site total leak testing for each HEPA-filtered PAPR used in a biocontainment setting. This testing evaluates the integrity of the filter itself and whether it is seated properly in the filter housing. On-site routine performance testing such as this provides an enhancement to the safety procedures governing research activities assigned to biosafety level 3 or animal biosafety level 3. The outlined test method is currently used in the Regional Biocontainment Laboratory at Duke University to verify proper filtration efficiency prior to placing newly purchased units into service and for annual reverification. Results from onsite testing with this method have demonstrated that some PAPR/HEPA filter systems fail to perform at the expected level of filtration efficiency, thus emphasizing the need for including this enhancement and regular testing in a comprehensive biosafety program that includes respiratory protection at biosafety level 3 or animal biosafety level 3 (ABSL-3).