Warning Properties In Respirator Selection.
NIOSH 1975 Dec:58 pages
Warning properties as a criterion for selecting respirators are discussed. Federal regulations specify that air purifying respirators approved for protection against organic vapors or acid gases may only be used when the air contaminant has adequate warning properties. The rationale is that a respirator user should be able to detect the end of sorbent life in his respirator. While the use of warning properties is not the most desirable technique to indicate sorbent breakthrough in a respirator, it is the currently accepted approach. Sensory and physiological effects that can serve as warning of the presence of toxic air contaminants are discussed. Odor, taste, and respiratory irritation are examined. Odor is an effective warning property if and only if the minimum identifiable odor is at least 10 times lower than the threshold limit value (TLV), and rapid anosmia is not induced. Irritation of the upper respiratory tract is a warning property if the threshold of irritation is lower than the threshold of toxicity. An examination of data of approximately 300 substances indicated that the minimum odor detection threshold was almost always well below the TLV. In a practical sense, only respiratory tract irritation is useful as a warning property. If data on the variation of odor intensity with concentration was available, it could be effectively utilized. It is recommended that NIOSH develop an end of service life indicator that does not rely on warning properties.
Exposure-limits; Gas-detectors; Exposure-levels; Lung; Inhalants; Respiration; Ventilation; Pulmonary-clearance; Analytical-models;
Division of Laboratories and Criteria Development, NIOSH, U.S. Department of Health, Education and Welfare, Cincinnati, Ohio, 58 pages, 45 references