Respirator selection criteria

The immediately dangerous to life or health (IDLH) air concentration values have been recommended by the US National Institute for Occupational Safety and Health (NIOSH) as respirator selection criteria. The current NIOSH definition for an IDLH condition is a situation that poses a threat of exposure to airborne contaminants when that exposure is likely to cause death or immediate or delayed permanent adverse health effects or prevent escape from such an environment. NIOSH s stated purpose for establishing IDLH values is to ensure that the worker can escape from a given contaminated environment in the event of failure of the respiratory protection equipment. The complete introduction and documentations to the 398 existing IDLH values can be read or downloaded at the NIOSH Internet website. 

Personal protection requirements for protection against exposure to substances that may cause injury by absorption through the skin from materials splashed or spilled on the skin are also important considerations. Respirator selection criteria are based primarily on the inhalation hazard of the substance. A snipplied-air suit may provide skin protection... 

Level C protection is distinguished from Level B by the equipment used to protect the respiratory system, assuming the same type of chemical-resistant clothing is used. The main selection criterion for Level C is that conditions permit wearing air-purifying respirators. An environment that would warrant donning Level 3 PPE would have the following characteristics ... 

As odor threshold is the criterion, if the odor threshold of a compound is greater than its TLV, overexposure of the respirator user is possible because breakthrough may not be detected. Individuals respond differently to the same odor. At a certain odor concentration, one person may detect the odor but not be able to recognize it another may recognize and detect it. A third might not even sense it at all. Table 19 compares 100% recognition thresholds with TLVs for selected compounds. 

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