Full text loading...
Chapter 17 : Personal Respiratory Protection
This chapter discusses the subject of respiratory protection to individuals working in the field of microbiology. Respirators can be divided into two general classes: atmosphere-supplying respirators and air-purifying respirators. Particles may be captured on a filter by both mechanical and electrostatic mechanisms. Four mechanical mechanisms contribute to particle deposition: interception, diffusion, gravity, and inertial impaction. There are very few recommendations for use of respiratory protection to control exposures to specific aerosolized microorganisms, or bioaerosols as they are sometimes called. Assigned protection factors (APFs) are designated by type of respirator. In simplified terms, the APF is the factor by which a properly selected and fitted respirator will reduce contaminant exposures. If an APF is 10, then the concentration of contaminant that reaches the wearer’s lungs will be reduced by a factor of 10. A qualitative method has been proposed for selecting respirators for protection in infectious aerosol environments which is based on the National Institute for Occupational Safety and Health (NIOSH) respirator decision logic. Respirator selection will be based on the best available practices, most current knowledge, and professional judgment and reemphasizes the need to utilize engineering and administrative controls when possible.
Key Concept Ranking
- Severe Acute Respiratory Syndrome
Supplied-air suit. (Courtesy of ILC Dover, Frederica, Del.)
(A) Filtering facepiece respirator, type N95. (B) Combination filtering facepiece respirator, type N95, and surgical mask. (C) Full facepiece respirator. (D) PAPR with hood. (E) PAPR with loose-fitting facepiece. (Courtesy of 3M Company, St. Paul, Minn.)
Typical components, facepieces, and clean-air sources for commonly used respirators
Particulate filter classes for nonpowered, air-purifying respirators
APFs for commonly used respirators
Recommendations relating to respirator use for biosafety applications