The effect of multiple donning on respirator fit in national health laboratory service employees during 2016

Abstract

Introduction Healthcare providers, laboratories and other industries in South Africa use N95 filtering face-piece respirators to reduce or protect themselves against exposure to airborne diseases such as tuberculosis. This is despite the fact that the use of personal protective equipment such as respirators is the least preferred means of exposure control in the occupational hygiene hierarchy of controls. The National Health Laboratory Service (NHLS) provides diagnostic laboratory services to all national and provincial health departments in South Africa. Thus, NHLS employees are potentially exposed to infectious agents such as Mycobacterium tuberculosis and are provided with N95 respirators to protect themselves. NHLS employees in some laboratories tend to take one respirator and use it for the whole shift or multiple shifts. These practices raise some concerns of damage due to multiple respirator donnings that can result in poor fit. A study in the United States of America (USA) recommended that re-using of a respirator should be limited to not more than five times to ensure a continued good seal. Study aim The aim of this study was to determine if multiple donnings of the same respirator could influence the face seal resulting in poor fit of respirators worn by the National Institute for Occupational Health (NIOH) employees during 2016. Study objective To measure and describe the effect on respirator fit following multiple donning and doffing of the N95 respirator by NIOH employees using the same respirator. The Effect of Multiple Donning on Respirator Fit in NHLS Employees Materials and methods This was a cross-sectional qualitative experimental study with descriptive components. NHLS employees from one institute, namely the National Institute for Occupational Health (NIOH) were invited to participate in the study. Study participants involved both respirator users exposed to hazardous biological agents and non-respirator users. Non respirator users refer to non-exposed personnel to hazardous biological agents i.e. administration office, librarian. Data were collected on 25 employees who participated in this study. All participants underwent six consecutive fit tests using the same respirator each time whilst performing dynamic movements. Quantitative respirator fit testing was conducted using the PortaCount fit testing equipment. A fit factor of ≥ 100 was considered satisfactory following OSHA protocol. STATA version 14 was used to perform data analysis. Results and discussion The 25 study participants all passed the fit test on the first donning. The fit test results on average gradually deteriorated after multiple consecutive donnings but the average fit factor remained above the cut off 100. A significant difference in mean fit factor was seen between the first and sixth donning but not between the second and sixth donnings suggesting that the donning method deteriorated after the first donning. The proportion of participants achieving a fit factor below 100 were eight percent for fit test two, 24% for fit test three, 32% for fit test four and five, then decreased to 28% for fit test six; although 13 (52%) achieved an overall fit factor of above 100 for all six consecutive fit tests. Four participants achieved a good overall fit factor of above 200 after six donnings. This experimental study results are in agreement with the findings of a National Institute for Occupational Safety and Health (NIOSH) study, which investigated the impact of multiple consecutive donnings on filtering face-piece respirator fit, and recommended five donnings of one respirator. The NIOSH study also established that the fit of the filtering face-piece respirator gradually decreased after multiple donnings and the best levels of fit were observed for donnings one to five. Some participants (6.25%) of this study showed an increased fit after six donnings. The Effect of Multiple Donning on Respirator Fit in NHLS Employees Respirator fit was demonstrated to vary over the consecutive donnings for most participants suggesting that the method used to don the respirator is very important to achieving a good fit. A third of participants failed a fit test and then passed in a subsequent fit test indicating the mask retained the ability to fit while the donning skill of the participant varied with each donning. The best overall fit factors were observed for donnings one and two (Table 3.5). Occurrences of two or more consecutive fit test scores of less than 100 were observed on eight participants. Persistent fit tests failures were observed on four participants. Head strap and nosepiece breaks were not witnessed in this study. Conclusion A satisfactory fit test score was found in the sixth fit test in 72% of the study participants. Variability in the donning technique was demonstrated by the 30% of participants who passed a fit test after failing a previous fit test. The consecutive multiple donnings of respirators carried out in this study demonstrated that while the respirator retains the ability to form a seal, not all respirator users will maintain acceptable levels of respirator fit following multiple donnings and doffings of the same respirator. Users and employers need to be aware of the increasing risk of unsatisfactory fit following multiple donnings and doffing of these devices and invest in regular training and other control measures.