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The authors ask you:
Respirators (respiratory personal protective devices) have traditionally been used in industrial type settings to protect healthy workers against known significant inhalational hazards. However, respirators may be increasingly employed in the service sector and in community settings because of concerns about epidemics or perceived terrorist threat. This project evaluates the feasibility of widespread utilization of respiratory protection, even by persons with mild respiratory impairments. Using a combination of work simulation and traditional pulmonary exercise laboratory methods, the effect of a half face mask (HFM) and an N95 respirator were evaluated. Measures included ten domains of subjective response, respiratory physiologic impact, effect on work productivity and accuracy, and maintaining the respirator mask in proper position. The studies suggest: (1) respirator use should be feasible on a widespread basis. (2) studies of subjective response must ask about multiple domains rather than depending upon a single question. (3) HFM typically had greater adverse impact than N95, although both were limited in extent. Respirator design and program policy should be updated to consider widespread community use.
Respirators have traditionally been used by healthy workers in settings with known significant inhalational exposure risks. Few research studies or practical assessments have addressed more widespread use. Infectious epidemics or perceived terrorist threat may impact a large proportion of the workforce. The "shelter in place" approach (i.e., discontinue non-essential occupational activities) would be extremely disruptive. Furthermore, there is inadequate information to guide decisions about whether respirators may be safely and effectively utilized by persons with mild respiratory impairments, which are very prevalent.
We created a work simulation laboratory in which multiple types of low-moderate exertion activities are conducted. Research volunteers are studied while using two different types of respirators (N95 and half face mask dual cartridge). Studies evaluate physiologic responses, subjective tolerance (including multiple types of effects), impact on work productivity, and continued use of the respirator (based upon video recording). Persons with mild asthma, mild COPD, and chronic rhinitis are involved as well as individuals without known respiratory disorders. Subjects also participated in a formal cardiopulmonary exercise laboratory session, in which carefully specified surrogate respirator loads may be studied under experimental control. Thus, it is possible to compare many different impacts of respirator use under conditions similar to "real-life work" and in carefully controlled laboratory settings. Physiologic studies were made possible by use of a noninvasive respiratory inductive plethysmograph system, allowing breathing measurements without mouthpieces.
In general, respirators were well tolerated by the mildly impaired subjects performing light to moderate work. Analysis of subjective responses showed that there were several different categories of response: "physiologic" (such as breathing, heat), "functional" (such as concentration and speech), and "minimal" (such as hearing). Overall, these respirator naive subjects tolerated N95 better than half face mask devices. Preliminary analyses suggest that, contrary to a priori expectation, persons with asthma and rhinitis show more adverse impact than persons with COPD. Physiologic impacts were demonstrable under several conditions. In general, such effects were less prominent during stimulated work than in the exercise laboratory setting.
Preliminary results suggest that respirators will be tolerated adequately by large numbers of individuals, permitting their widespread use in any event of respiratory epidemics or enhanced terrorism related perceived threats. Even persons with mild respiratory problems should be able to continue working. The greater protection factor of half face mask devices may be counterbalanced by the slightly reduced tolerance with possible consequent underutilization.
The research studies are ongoing, currently focusing on delineating the interaction among health status, physiologic response, subjective response, and proper utilization. Respirator design and program requirements originally developed for healthy workers and workplaces with known significant hazards may not be optimal for widespread worker and community applicability. In the future, research and practical efforts are required to develop and test respirators that are applicable to the general population. There is also a need to develop effective methods for providing respirators widely and for properly training workers and community members in their correct utilization.
The findings and conclusions in this poster are those of the author(s) and do not necessarily represent the views of the National Institute for Occupational Safety and Health. Citations to Web sites external to NIOSH do not constitute NIOSH endorsement of the sponsoring organizations or their programs or products. Furthermore, NIOSH is not responsible for the content of these Web sites.
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