a description of specific risks to each exposed individual due to infection, any subsequent treatment with isoniazid, and the possibility of active disease. Necessary topics are detailed in section V.D.3 starting on page 43.
G. Surgical Masks and Other Disposable Particulate Respirators—As noted, NIOSH has reexamined the hazards of aerosolized droplet nuclei containing tubercle bacilli and the role, reliability, and efficacy of various personal respiratory protective devices to protect healthcare-facility workers against transmission of airborne tuberculosis. Based upon this reexamination, NIOSH concluded that negative-pressure, non-elastomeric, cup-shaped, disposable, particulate-filter respirators ( PRS) without HEPA filters (e.g., surgical masks not certified by NIOSH; NIOSH-certified dust and mist filters; NIOSH-certified dust, fume, and mist filters) cannot be relied upon to protect workers exposed to infectious tuberculosis. These devices include those negative-pressure, non-elastomeric, cup-shaped, disposable masks that consist partly or entirely of filter media integrated into the facepiece. That is, certain "maintenance-free" masks with filtering facepieces for which it is difficult, if not impossible, for a wearer to cover the entire filter-surface area, but not cover the face seal between the respirator and the wearer's face.
This conclusion is based on a body of data indicating that these cup-shaped, disposable masks cannot provide effective and reliable personal respiratory protection due to: (1) unreliable face-seal efficacy, (2) inevitable and dangerous face-seal leakage, and (3) potentially excessive filter leakage (46,59,90,91,92,93).
Face-seal leakage has long been recognized by respirator specialists as compromising adequate personal protection from any air-purifying respirator, particularly negative-pressure halfmask respirators (55,94,95). As noted, existing standard performance tests for surgical masks have not addressed either face-seal leakage or the effects that prolonged use might have on this leakage (59).
