The development and use of respirator response functions as part of a workplace exposure monitoring program for control of potential respiratory hazards.

The traditional hierarchy of measures for control of potential respiratory hazards in the workplace includes (in order of preference) engineering controls, workplace practices, and use of respiratory protection. Although third in this hierarchy, respirators can be an important component of the control mix-particularly for difficult-to-control jobs, as an interim measure (pending implementation of other controls), and in cases where exposure is intermittent. One of the problems associated with the use of respirators as a control measure is that valid and adequate data on respirator usage are often not available. Absent these data it is difficult to determine the practical effectiveness of respirators and exposure calculations which include the protective effect of respirators are speculative. This paper presents models (and appropriate statistical fitting techniques) suitable for quantification of respirator usage and defines three potentially useful measures of effectiveness for a respirator program. These models are illustrated with monitoring data on refractory ceramic fiber (RCF) developed as part of a Consent Agreement between the RCF industry and the U.S. Environmental Protection Agency. For this substance there are extensive and comprehensive monitoring data available. The models and methods of analysis may prove applicable for other potential respiratory hazards in the workplace.