Protection Factor Study Findings

The protection factor studies described in Table 2-2 demonstrate that, after fit testing, reusable elastomeric respirators exceeded OSHA respiratory protection standards for air-purifying respirators (Lawrence et al., 2006; Duling et al., 2007; Cho et al., 2010; Zhuang et al., 2014; Vo et al., 2015) and may provide better protection than disposable filtering facepiece respirators due to their superior sealing and fit characteristics (Lawrence et al., 2006; Duling et al., 2007; Cho et al., 2010; Vo et al., 2015). Additionally, the available research shows that there is likely significant variability in protectiveness afforded by different individual models of respirators of the same type (i.e., differences in the protectiveness of different models of filtering facepiece respirators) (Lawrence et al., 2006; Vo et al., 2015). In the single SWPF study that considered the protectiveness of reusable elastomeric respirators in a simulated health care environment, reusable elastomeric respirators provided improved protection for the user and, as a class, performed 60 percent better than their disposable filtering facepiece counterparts (Duling et al., 2007). Vo and colleagues (2015) also found evidence of the superior protection of reusable elastomeric respirators over a disposable filtering facepiece respirator within the same level of filter efficiency and across a broad range of particle sizes (p<0.05). P100 reusable elastomeric respirators were found to provide better protection than P100 disposable filtering facepieces (5th percentile SWPF of 3,777 compared to 1,574) against nanoparticles 10 to 100 nm in size. This pattern of performance was mirrored at the N95 efficiency level and with particles 100 to 400 nm in size. Reusable elastomeric respirators were also found to provide 2.4 times higher WPF than the disposable filtering facepiece respirators tested across all particle sizes tested in an agricultural setting (p = 0.0001) (Cho et al., 2010).

TABLE 2-2

Recent Studies on the Performance of Half-Facepiece Reusable Elastomeric Respirators.

In addition to the recent research highlighted in Table 2-2, several WPF studies performed in a variety of industries—mining, agriculture, foundries, etc.—have reported that elastomeric respirators meet and often exceed the minimum levels of workplace protection established by OSHA for air-purifying respirators (Myers et al., 1996; Zhuang and Myers, 1996; Myers and Zhuang, 1998; Liu et al., 2006; Cho et al., 2010; Janssen and McCullough, 2010). A WPF study of reusable elastomeric respirator models in use in an aircraft paint-spraying operation found that WPF exceeded 10 in all workplaces and activities tested (mean 5th percentile of all WPF samples was 388) (Zhuang and Myers, 1996). Similarly, a steel-mill-based study found that all air-purifying respirators tested, including both disposable filtering facepiece and reusable elastomeric respirators, exceeded 10 WPF (reusable elastomeric respirator 5th percentile ranged from 39 to 56) (Myers and Zhuang, 1998). A WPF study conducted in a lead battery plant found that the mean 5th percentile WPF protection provided by the P100 reusable elastomeric respirators tested exceeded 50, with 5th percentile WPF values ranging from 12 to 2,500. The researchers concluded that, based on prior research, these findings do not suggest that there are significant differences between the WPFs of disposable filtering facepiece and of reusable elastomeric respirators (Janssen and McCullough, 2010). Several WPF studies conducted both before and after the establishment of OSHA's assigned protection factor, including a study conducted in a foundry (Myers et al., 1996) and a lead battery plant (Janssen and McCullough, 2010), concluded that there were no significant differences in the WPFs of reusable elastomeric respirators versus the WPFs of disposable filtering facepiece respirators.

Beyond assessing protection factors, these SWPF and WPF studies provided further evidence on the interrelated elements of respirator efficacy—fit, leakage, and filter penetration—and further suggested how these characteristics may affect respirator performance under conditions of real-world use.

Fault-Tolerant Protection

Advocates for the use of reusable elastomeric respirators have pointed to anecdotal evidence from users across industries, including health care, that reusable elastomeric respirators provide a more fault-tolerant fit—that is, a secure face seal is more easily achieved and less prone to human error than when donning and using a disposable filtering facepiece respirator (Chang, 2018). While the fault tolerance of the reusable elastomeric respirator face seal has not been quantitatively tested in a real-world setting, Lawrence and colleagues captured data on SWPF for both reusable and disposable respirators prior to and after fit testing (see Table 2-2). Their data show that prior to fit testing, the 15 reusable elastomeric respirators, as a class, obtained significantly higher levels of protection than the 15 disposable filtering facepiece respirators (mean 5th percentile SWPF of 7.3 versus 3.3), although none met the minimum 5th percentile requirements for protection prior to fit testing (Lawrence et al., 2006). Furthermore, the mean 5th percentile of reusable elastomeric respirators that failed fit testing were found to be more protective (6.3 with Bitrex; 6.2 with Saccharin; and 4.4 with Portacount Plus) than the same measures for the disposable filtering facepieces (3.0 with Bitrex and 3.0 with Saccharin; 2.7 with Portacount Plus) (Lawrence et al., 2006). These findings may suggest that, despite the use of an improperly worn or not-fit-tested elastomeric respirator, users may experience higher levels of protection with a reusable elastomeric respirator than with an improperly worn or poor-fitting disposable filtering facepiece respirator.

Fitting Characteristics

The design of a respirator affects its ability to create a secure face seal; therefore, differences in design features both across and within respirator classes can result in variations in the level of protection provided to a user (Vo et al., 2015). Few studies have compared the fitting characteristics of reusable elastomeric respirators with the role that these characteristics may play in providing protection for the user (Lawrence et al., 2006; Duling et al., 2007). Lawrence and colleagues (2006) calculated the h-value of each of the models of respirators under study. (An h-value greater than or equal to 0.95 indicates that 95 percent or more of users obtained a SWPF of 10 or greater.) The 15 models of reusable elastomeric respirators scored a mean h-value of 0.92 (range, 0.79–0.99), compared with 0.74 (range, 0.05–0.98) for N95 disposable filtering facepiece respirators. Furthermore, only two of the 15 models of disposable filtering facepieces tested demonstrated good fitting characteristics, versus 7 out of the 15 reusable elastomeric respirators tested (Lawrence et al., 2006). Further highlighting the importance of fit in performance, Han and Lee found that face seal leakage among disposable filtering facepiece users varies significantly by facial dimensions (Han and Lee, 2005). This finding underscores the importance of designing well-fitting respirators for health care and suggests that reusable elastomeric respirators, on average, may have superior fitting characteristics. As a result, a reusable elastomeric respirator may offer consistently better effectiveness during day-to-day use than the disposable filtering facepiece respirator. More field research is needed to better understand how respirator fit affects performance (Janssen and McCullough, 2010).

Leakage

Leakage is an outcome of both the fitting characteristics and the use of a specific respirator, and face seal leakage, specifically, is the most variable and critical factor of the total inward leakage of a respirator (Han and Lee, 2005; IOM, 2008; Cho et al., 2010; He et al., 2013). The penetration of particles has been shown to increase as the size of the leak increases for both disposable filtering facepiece respirators (Rengasamy and Eimer, 2011) and reusable elastomeric respirators (He et al., 2013). Significant variation in face seal leakage has been observed across respirator classes), as has variation in leakage across respirator models within the same class (Coffey et al., 1999; Han and Lee, 2005). Coffey and colleagues (2004) found that the 5th percentile SWPFs varied significantly across 18 N95 disposable filtering facepiece respirators without fit testing, ranging from providing the user almost no protection to exceeding the minimum level of protection (1.3 to 48.0 SWPF). Other research has shown that, although the protection provided by reusable elastomeric respirators varies, as a class these respirators may have significantly less leakage than disposable filtering facepieces (Han and Lee, 2005; Lawrence et al., 2006).

Furthermore, research suggests that the sealing surface of the disposable filtering facepiece respirator may be more susceptible to damage than that of a reusable elastomeric respirator. And, in order to secure a good fit with a disposable filtering facepiece respirator, the user often needs to manually alter the respirator's fit (using elastic straps or the malleable metal nosepiece) each time the respirator is donned. This process introduces more opportunity for user error (Lawrence et al., 2006; Vo et al., 2015), a situation that is exacerbated by the user's inability to easily conduct a rapid user seal check to confirm that a secure seal has been achieved by manual adjustments. Other ways in which the design of reusable elastomeric respirators differs from the design of disposable filtering facepiece respirators, such as the presence of adjustable headstraps, have also been suggested as factors that may account for a more fault-tolerant fit and a higher protection factor. Thicker, adjustable straps are less likely to shift on the wearer's head and can be tightened to create a customized seal, although this effect has not been measured quantitatively (Lawrence et al., 2006).

Although there is a dearth of research specific to the performance of reusable elastomeric respirators in a health care setting, available evidence suggests that these respirators may be less prone to leakage (Han and Lee, 2005) due to several factors: the soft flexibility of the durable elastomeric seal, which eliminates the need to manually conform the seal or the adjustable nosepiece to the face at each use; the ability to carry out an on-the-spot user seal check; and the adjustability of secure headstraps (Lawrence et al., 2006; Vo et al., 2015). Additional research will be required to better understand the correlation between fit, temporary leakage, and stability of the reusable elastomeric respirator during use (Janssen and McCullough, 2010) as well as how these measures compare with those of disposable filtering facepieces.

Impact of Particle Size and Filter Efficiency on Performance

Particle penetration, either through the filter media or through face seal leakage, is another component of the total inward leakage and, by extension, of the performance of a respirator. A variety of well-studied factors affect filter penetration, including filter type, flow rates, and particle size (Shaffer and Rengasamy, 2009; He et al., 2013). The selection of a respirator for use in a respiratory protection program must consider these factors in order to ensure that the respiratory protective device type and filter efficiency selected can safely manage the workplace exposure.

In SWPF studies, filter efficiency has been shown to significantly affect air-purifying respirator performance (Zhuang et al., 2014; He et al., 2015; Vo et al., 2015). A study by He and colleagues (2015) found SWPFs to be significantly different between P100 and N95 class respirators—both disposable filtering facepieces and reusable elastomeric respirators were tested—with the P100 level of efficiency providing better protection for the user. Across all particle sizes (10 to 400 nm), respirators equipped with N95 class filters were found to have generated a mean 5th percentile SWPF of >10, while the respirators with P100 class filters obtained a superior 5th percentile mean of SWPF >100 (He et al., 2015). These findings suggest that P100 filters, regardless of respirator type, provide superior protection in workplaces where contaminants are within the most penetrating particle size range of 40 to 200 nm, as described in this study (He et al., 2015). While there is a lack of research regarding the performance of reusable elastomeric respirators when exposed to influenza aerosols, a study on the performance of N95 disposable filtering facepiece respirators found that the performance of these respirators was, likewise, affected by particle size rather than particle type and that their performance was equivalent or better than OSHA standards in reducing exposure.

Manual Reprocessing

Wipes, which are already available in health care settings, have been suggested as a highly accessible tool for the initial cleaning and disinfection of respirators performed by health care workers between patient visits. However, there are two potential issues related to fomite contamination that may impede the use of wipes: fabric headstraps cannot be effectively wiped, and human error may result in incomplete cleaning and disinfection.

Subhash and colleagues (2014) focused exclusively on the disinfection of the reusable respirator facepiece by comparing the efficacy of three different disinfection methods using wipes. They found that the two-part method using a 0.28 percent quaternary ammonium chloride wipe followed by a 17.2 percent isopropyl alcohol wipe was most efficacious in removing influenza from the surface of the facepiece. The bleach-detergent wipe was found to be next most efficacious. However, the authors point out that the polymerase chain reaction (PCR) method is more sensitive than cell culture in detecting viral RNA, and it may detect the presence of viral RNA that may not be infectious. As the researchers note, “Persistent RNA may simply represent non-infectious viral nucleic acid. None of the disinfectants tested destroys nucleic acid as a primary mode of action” (Subhash et al., 2014, p. 895). As such, PCR is not necessarily an effective surrogate measure for the presence of a viable virus. When the researchers used cell culture instead of PCR, no recoverable influenza virus was found on the facepiece after either the quaternary ammonium chloride-isopropyl alcohol wipe or the bleach-detergent wipe (Subhash et al., 2014). The isopropyl alcohol wipe was found to be least efficacious; 75 percent of the respirators treated by this wipe were found to be positive by cell culture and 83 percent by PCR.

A 2017 study by Lawrence and colleagues specifically considered the effectiveness of the cleaning and disinfecting of fabric headstraps. Their findings suggest that in a controlled environment, cleaning with water and a detergent is as effective as disinfection at removing viruses from the reusable elastomeric respirator. No significant difference was found in the recovery of viral material after cleaning versus after disinfection (Lawrence et al., 2017). This study was the only one to specifically address the efficacy of cleaning and reprocessing the fabric straps of the reusable elastomeric respirators. All instances of recoverable virus were found on the respirator's straps—two instances in the case of cleaning only and one instance using the bleach disinfection method—which suggests that further research is necessary to establish best practices for respirator reprocessing. The researchers hypothesized that the hydrophilic nature of the fabric straps on two of the models of reusable elastomeric respirators tested may have hampered the cleaning process and allowed viable virus to be recovered (Lawrence et al., 2017). The hydrophilic design of the headstraps on these two models, which may be beneficial for use in other industries, may not be suited for use in a health care setting.

The findings of these two studies on manual cleaning and disinfection suggest that there are methods for the cleaning and disinfection of reusable elastomeric respirators that are efficacious in eliminating recoverable influenza viruses from the surface of the device. Particularly, disinfection using a wipe impregnated with quaternary ammonium chloride and isopropyl alcohol or a wipe impregnated with both bleach and detergent may be sufficient for disinfecting the surface of the facepiece and cartridges immediately after doffing (Subhash et al., 2014). Additionally, reprocessing using a full submersion method with a detergent to remove surface buildup, such as oils and dirt, may be as effective at removing viral material as disinfecting with a bleach solution (Lawrence et al., 2017). More research is needed to further understand and confirm the findings of this small body of research on the reprocessing of reusable elastomeric respirators following use in a health care setting.

Automated Reprocessing

Research carried out by Applied Research Associates suggests that automated reprocessing using a machine washer can be effective in removing viable influenza virus from the surface of the reusable elastomeric facepiece and its straps (see Table 2-4). Following disinfection with an automated washer set to 55°C (a temperature within the manufacturer-established temperature limits) and a neutral detergent solution, no viable virus was recovered from any surface of the respirator (Heimbuch, 2018).

The findings of this limited body of research on the reprocessing of reusable respirators in health care suggests that both manual and automated reprocessing are capable of eliminating viable virus from the surfaces of a reusable elastomeric respirator (Subhash et al., 2014; Lawrence et al., 2017). Several processes (manual wiping, submersion in a solution, and automated washing) and disinfectants (bleach and quaternary ammonium chloride) have been shown to be efficacious. However, there is a lack of clarity about when cleaning versus disinfection should be performed and whether straps or crevices not reached by a disinfectant wipe could pose a risk to the user or others.

Fomite Transmission

How well a reusable elastomeric respirator will work in a health care setting remains an unsolved issue. Viruses can remain viable on surfaces for hours and can cause disease through surface-to-hand and hand-to-hand transmission. The severe acute respiratory syndrome (SARS) experience revealed concerns regarding the self-contamination of health care workers during the process of doffing PPE (Casanova et al., 2008); however, the role of fomite transmission for other agents, such as novel influenza viruses, remains unclear. Additionally, little is known about the risk to workers from contact with contaminated elastomeric respirator surfaces during cleaning and disinfection (Lenhart et al., 2004), or about the potential risk of transmission during use over the course of a shift. This lack of clarity concerning fomite transmission and safe use can deter decision makers from considering reusable elastomeric respirators as a component of their respiratory protection program (Barsky, 2018; Petersen, 2018).

Findings and Gaps in the Literature on the Effectiveness of Cleaning and Disinfection

The findings of each of these three studies on the reprocessing of reusable elastomeric respirators demonstrate that several methods of cleaning and disinfection are effective in removing viral material from the surface of reusable respirators, including fabric headstraps. These findings, combined with the overall lack of research on this topic, highlight key gaps in the knowledge base of the infection prevention and control field regarding the use of reusable elastomeric respirators in health care. Specifically, these gaps include whether (1) the fomite contamination of headstraps and other respirator surfaces by influenza and other pathogens represents a significant risk to users, other health care workers, and patients; (2) the methods shown to be effective in eliminating influenza will be similarly successful on other pathogens prevalent in the health care setting; and (3) these processes can be reproduced in the field with similar results.

Health Care–Specific Procedures

Manufacturer instructions for respirator cleaning and/or disinfection are included when the product is purchased. However, these instructions are developed for respirator use across multiple industries and often do not address important issues for the health care setting, including details on what PPE should be worn during cleaning, minimum contact time of the respirator with the disinfectant for effective disinfection against biological contaminants, and how to address logistical issues such as respirators floating during submersion in disinfecting solutions (Bessesen et al., 2015). These issues can be addressed by developing cleaning and disinfecting procedures specifically designed for use by health care workers. A small, 21-participant study conducted in a Colorado Veterans Affairs hospital system found that health care workers demonstrated the ability to implement a novel disinfection protocol by following an iteratively developed standard operating procedure (Bessesen et al., 2015). The study found that the use of the optimized, researcher-created instructions allowed naive participants to carry out the modified procedure with no observed errors. Comparatively, out of 66 attempts with manufacturer instructions, 31 errors were observed. Studies on endoscope processing found similar benefits to the use of iteratively developed standard operating procedures or instructional aids specifically designed for the health care user (Jolly et al., 2013). The value of developing health care worker–specific standardized operating procedures will be particularly high in a surge scenario, where the rapid implementation of a novel reusable respirator may require staff to carry out the reprocessing process without extensive training and to a high degree of adherence. The optimized operating procedure developed by Bessesen and colleagues required a sink with room for two 2-gallon buckets, an immersible thermometer, and a water temperature between 85°F and 100°F. Participants used tongs to turn the submerged facepiece to remove air bubbles and keep the facepiece submerged. Instructions included a request for gentle handling to avoid dislodging important components (Bessesen et al., 2015).

On a related note, the lack of standardized disinfection guidance on the type and concentration of disinfectant needed to effectively disinfect reusable elastomeric respirators in health care puts the burden of selecting and then preparing the correct concentration of the solution on the health care facility and workers. This issue is further complicated when the health care facility uses more than one model of reusable respirator, each with its own unique disinfection process and with varying specifications concerning the concentrations of commercially available bleach. Bessesen and colleagues (2015) noted that manufacturer-recommended bleach concentrations for the three models studied ranged from 50 to 400 parts per million (ppm) and that the bleach available for purchase ranged in concentration from 5.25 to 6 percent hypochlorite (hospital supply firms) to 8.25 percent (retail). These variations mean that health care workers, in the absence of a universal disinfection standard for reusable elastomeric respirators, require instructions that clearly identify what bleach concentration should be used and how to achieve the appropriate concentration of disinfection solution (Bessesen et al., 2015).

Centralized Reprocessing

Centralized, automated reprocessing of reusable elastomeric respirators is practiced in general industry, particularly in workplaces where workers share reusable respirators and are not directly responsible for respirator maintenance. In health care, there are some examples of facilities choosing to use a centralized model for reprocessing PAPRs (IOM, 2015), but there is limited experience in working with elastomeric respirators. Both TCID and UMMC, the two institutions known to use reusable elastomeric respirators, delegate cleaning and disinfection responsibilities to the individual user. The WorkSafe BC study, which evaluated the implications of using a centralized disinfection model at three large, acute-care hospitals, found that the manufacturer's cleaning and disinfection requirements differed from the processes used by their sterile processing units. Investigators noted that, per the manufacturer's guidelines, the reusable respirators used by the hospitals were not able to withstand temperatures greater than 120°F, and as such were not able to be dried using the sterile processing units' driers, which dried at 140°F. These temperature differences abruptly ended the hospitals' plans to reprocess reusable elastomeric respirators in the same manner that it handles other reusable equipment, thus substantially increasing the time needed to manually clean and disinfect the equipment. Additionally, other logistical issues such as the lack of robust equipment-tracking systems and inconsistent equipment transportation system practices within each hospital further challenged the feasibility of the centralized model (Ciconte et al., 2013).

Time Burden

The amount of time needed to effectively clean and disinfect a reusable elastomeric respirator also represents a challenge, particularly in scenarios where health care workers are required to perform the reprocessing themselves (Ciconte et al., 2013; Bessesen et al., 2015; Puro et al., 2015; Lawrence et al., 2017). Total cleaning and disinfection times varied depending on the methods used. Of the limited number of studies that have been done, most focused on reprocessing performed by health care workers. In the study by Bessesen and colleagues, cleaning took an average of 16 minutes per respirator, and reattaching the filters and preparing the solution were the most time-consuming parts of the process (Bessesen et al., 2015). In the WorkSafe BC study, respirators were first cleaned—soaked in a cleaning solution, scrubbed, and rinsed—and then disinfected by being soaked in a disinfecting solution and rinsed for a final time before being left to air dry. Investigators reported that the facepieces floated during soaking, which was not addressed by the manufacturer instructions, and this doubled the reprocessing time to 24 minutes per respirator because the facepiece had to be flipped halfway through soaking to achieve adequate contact time on both sides (Ciconte et al., 2013). Lawrence and colleagues (2017) reported that a cleaning-only process based on OSHA recommendations required 2 to 3 minutes per respirator. Cleaning and then disinfection was performed in batches of three devices at a time and required approximately 21 minutes per batch. Neither of these time calculations accounted for the preparation time required to sterilize and prepare the cleaning materials. Average air-drying time was 20 minutes for facepieces and more than 6 hours for elastic headstraps.

Beyond the time required to perform the actual reprocessing, it was reported that having too few dedicated cleaning stations could result in significant wait times at the end of shifts. Such time-related challenges could be lessened in an emergency scenario by having prepared disinfection solution on hand, and exploring alternative models for mass disinfection of reusable respirators.

These findings suggest that while the cleaning and disinfecting of reusable elastomeric respirators is effective in removing viruses from the surface of the respirator, significant logistical barriers exist that may jeopardize the feasibility of reprocessing, particularly during an emergency scenario. Time burdens on the users may be considerable because of the cumulative amount of time required to wash and then air dry the device, including the straps, before storing the respirator in a personal locker or a labeled bag.

Access to Dedicated Facilities

The cleaning and disinfection of reusable elastomeric respirators requires a dedicated space, and this has been cited as a significant barrier to the feasibility of using these respirators in health care facilities (Ciconte et al., 2013; discussed in Chapter 3). Furthermore, cross-contamination between used and cleaned respirators needs to be avoided, which requires clearly demarcated spaces. The limited amount of space available in clinical care units makes it difficult to identify where and how dedicated and accessible spaces could be allocated for reprocessing and storage (Ciconte et al., 2013).

Durability

Few studies have been conducted to quantitatively assess the impact that repeated reprocessing using detergents and disinfectants has on the durability of reusable elastomeric respirators; however, experience with reusable elastomeric respirators in general industry has demonstrated that these respirators can handle regular reprocessing—provided that manufacturer instructions are followed and dedicated maintenance is performed. In one study performed by Applied Research Associates, reusable elastomeric respirators were evaluated for changes in fit, inhalation resistance, and valve leakage after 150 cycles of manual cleaning and disinfection (bleach solution) and 100 cycles of automated reprocessing. No significant changes were reported following 150 cycles of manual cleaning and disinfection (Heimbuch, 2018). Of the five reusable elastomeric respirator models examined in the study, all maintained adequate inhalation resistance and valve leakage, and all but one maintained adequate fit. Bessesen and colleagues also specifically assessed changes in the elasticity of headstraps from three different models of reusable elastomeric respirators following 45 cycles of disinfection using a bleach disinfectant solution. Compared to the length of the strap at baseline, one model showed no decrease in elasticity, while the other two models stretched by 7.1 and 3.9 percent (Bessesen et al., 2015).

OSHA

Unlike the FDA system, OSHA's guidance is not based on how the device is used or its risk. Rather, OSHA requires all worksites using reusable respirators, regardless of exposure, to have an established reprocessing procedure that uses cleaning and disinfection procedures as recommended by OSHA (see Box 2-6) or to use a procedure that follows the manufacturer instructions (at least equivalent to the minimum standards set by OSHA) (Lawrence et al., 2017).⁵

BOX 2-6

OSHA Procedures for Cleaning Respirators.

The OSHA regulation does not specify the frequency of cleaning and disinfection required, other than to require that respirators exclusively used by a single employee “be cleaned and disinfected as often as necessary to be maintained in a sanitary condition.”⁶ The OSHA standard further specifies that respirators that are specifically for emergency use “be cleaned and disinfected after each use.”⁷ Beyond the frequency of reprocessing, the OSHA regulations, as well as many manufacturer instructions, fail to describe the PPE that should be worn to protect the user from detergents and biological contamination during cleaning and disinfection, a consideration that is particularly important given the risks associated with health care exposures.⁸

Manufacturer Instructions for Use

Given the complexities of safely carrying out cleaning and disinfection at the appropriate times, health care workers need clear instructions for safely and effectively reprocessing elastomeric respirators (Lawrence et al., 2017). However, as this clear guidance is lacking, reprocessing must follow the established processes documented in the manufacturer instructions for use. These instructions are specific to each respirator model and can have varying levels of detail (i.e., unspecified contact times), materials required, and processes (varying concentrations of non-specific or manufacturer-supplied disinfecting solutions) (Lawrence et al., 2017). Hospitals and other health care organizations must use manufacturer instructions for all equipment cleaning and disinfection in order to meet the Joint Commission and the Centers for Medicare & Medicaid Services standards, or they must perform a comprehensive risk assessment that supports their alternative methods of cleaning and disinfection. Table 2-5 provides examples of instructions provided by manufacturers on cleaning and disinfection.

Temperature Discomfort and Skin Irritation

When a user must wear a respirator for extended periods, the feeling of the device on the face and the comfort of the materials during use become important considerations. As described in Chapter 1, reusable elastomeric respirators and filtering facepiece respirators each require a tight face seal to function. However, the materials that create this seal, as well as the microenvironment that forms in the air pocket around the nose and mouth, can feel different for the user in different respirator types and models. The limited porosity of the elastomeric seal and facepiece can impair the radiation of heat and evaporation of moisture from exhaled breath, thus limiting the dispersal of heat and humidity inside the air pocket (Roberge, 2018). Users of reusable elastomeric respirators have specifically cited feelings of warmth, facial sweating, and skin irritation as contributing factors to user discomfort (Roberge et al., 2013). Users of disposable filtering facepiece respirators have cited similar complaints related to temperature and discomfort during use (Baig et al., 2010; Ciconte et al., 2013; Chen et al., 2017). In one qualitative study, 54.4 percent of respondents reported that filtering facepiece respirators were never or rarely comfortable to wear (Baig et al., 2010).

Despite these reports, there has been very little research conducted to better understand the differences in comfort during the actual use of these respirators in a health care setting, particularly during periods of prolonged use (Shenal et al., 2012). Several laboratory-based studies found that during physical exertion that mimicked the activities of the workplace, the temperature and humidity of respired air inside the disposable filtering facepiece was greater than inside the reusable elastomeric respirator (Roberge et al., 2010; Chen et al., 2017).

Users have also noted other types of discomfort as well. The use of reusable elastomeric and other tight-fitting respirators on a freshly shaven face has been reported to result in instances of skin irritation (Floyd et al., 2018). Additionally, some users have reported discomfort when wearing the reusable elastomeric respirator with glasses, due to the positioning of the glasses and the respirator on the face (Ciconte et al., 2013).

Respirator Weight, Harness, and Size

The weight of the respirator is another important factor in comfort for users; generally speaking, the heavier a respirator is, the greater the likelihood that it will contribute to the fatigue of the user. Weight may be a more significant consideration with prolonged use and higher exertion rates (Roberge et al., 2010; Johnson, 2016). Also, the size of the respirator has been reported by some users to interfere with the downward visual gaze of the user (Brinker et al., 2007; Johnson, 2016), although there are few published qualitative or quantitative data available that elaborate on the level and extent of interference.

In addition to supporting the respirator's weight, the straps must stabilize the respirator on the face, and how well they perform this job, combined with the design of the straps, collectively affects the overall comfort of a respirator during use. Thinner straps are thought to exert more pressure on the face, whereas wider straps can better distribute the respirator's weight. Additionally, comfort can be affected by whether or not the strap position or material pulls on the user's hair, or whether the straps can be adjusted easily (Birkner, 2012). Reusable elastomeric respirators typically feature these wider, adjustable headstraps, as compared to many disposable filtering-facepiece respirator models, which are equipped with thin elastic straps that must be adjusted at every use. Furthermore, some reusable elastomeric respirators are equipped with head cradles that consistently position the top strap at the crown of the head, thus allowing for a more consistent fit. Importantly, adjustable straps of the reusable elastomeric respirator may create a more customized seal for the user (i.e., having one strap tighter than the other strap) and, therefore, provide greater protection and comfort (Lawrence et al., 2006) (see section Efficacy and Effectiveness of Half-Facepiece Reusable Elastomeric Respirators). However, the tight seal provided by the respirator straps has been reported by some users to cause headaches due to pressure on the sinuses (Ciconte et al., 2013), although complaints relating to pain and pressure are not exclusive this respirator type (Lim et al., 2006; Radonovich et al., 2009).

Work of Breathing

Breathing patterns are predictably altered by the use of respirators, as the inhalation and exhalation of breath requires the expenditure of energy (work), which increases when using a respirator (Johnson, 2016). Implicitly, the easier it is for the user to inhale and exhale, the less fatigued they will be after use. Although research is limited, the use of a reusable elastomeric respirator in simulated health care working conditions over a 1-hour period has been demonstrated to decrease breathing rate (p = 0.02) and increase tidal volume (p = 0.009) compared to controls among 10 healthy volunteers (Roberge et al., 2010).

Per NIOSH's requirements, respirators must meet inhalation and exhalation resistance criteria; however, NIOSH only sets a maximum resistance level (35 mm water column height pressure for initial inhalation, 25 mm water column height pressure for initial exhalation).¹¹ The lower the breathing resistance, the more comfortable the user is when using the device and the more likely that the user will comply with using the respirator when required. Research has demonstrated that increased breathing resistance can result in the user feeling out of breath or claustrophobic (Wu et al., 2011; Johnson, 2016).

Carbon Dioxide Buildup

The buildup of carbon dioxide in the respirator's dead space is a concern and a potential cause of discomfort for respirator users in general, as there have been some reported instances of headaches and rapid breathing after the use of N95 disposable filtering facepiece respirators (Lim et al., 2006; SARS Commission, 2006; Rebmann et al., 2013). Past research has primarily focused on disposable filtering facepiece respirators because of their widespread use in health care. In one survey, more than one-third (37.3 percent) of health care workers (n = 212) who wore filtering facepieces for extended periods of time during the SARS outbreak reported that they experienced headaches. Further analysis found that the continuous use of the filtering facepiece respirator (>4 hours of continuous wear) was associated with the development of headaches (p = 0.053) (Lim et al., 2006).

Few studies have tracked changes in carbon dioxide levels within the dead space of reusable elastomeric respirators and symptoms of hypercapnia among health care workers. In one study, transcutaneous carbon dioxide levels were elevated (>45 mm Hg) after 45 minutes of activity at a simulated work rate (2.5 mph on treadmill) among 5 out of 10 participants (range, 45.4 to 62.8 mm Hg) wearing elastomeric respirators equipped with an exhalation valve. The dead space concentrations of oxygen (17.85 percent) and carbon dioxide (2.5 percent) generated at this simulated work rate failed to meet OSHA's standards for ambient air in the workplace (<19.5 percent oxygen is considered to be oxygen deficient, 0.5 percent carbon dioxide is the threshold for maximum exposure over an averaged 8-hour period). However, it should be noted that these standards are not specifically applicable to respirator dead space. Despite increased carbon dioxide levels, no participants reported experiencing symptoms of hypercapnia (Roberge et al., 2010). More research is needed to better understand whether the extended use of reusable elastomeric respirators over lengthier periods is associated with an increased exposure to carbon dioxide or to user discomfort (Roberge et al., 2010; Ciconte et al., 2013).

Anxiety and Distress

Considerations about the psychological response of health care workers to the introduction and use of reusable elastomeric respirators in the workplace are critical for decision making, as compliance is essential for protection. However, little is known about psychological responses to the use of reusable elastomeric respirators among health care workers experiencing the unique demands of a health care environment (Roberge et al., 2010; Wu et al., 2011). What is known is that many members of the general population live with general anxiety or panic disorders, which can be triggered by the perceived or actual physiological outcomes of respirator use (Morgan, 1983; Wilson et al., 1999). The known triggers of anxiety or distress for reusable elastomeric respirators include increased breathing resistance, increased carbon dioxide levels in the facepiece's dead space, and visual and communication limitations (Roberge, 2018).

Wu and colleagues (2011) found a statistically significant increase in state anxiety during the use of reusable elastomeric respirators by participants and no significant increase during the use of disposable filtering facepiece respirators. This small study involved 12 subjects in a simulated work environment performing set tasks that ranged from sedentary to requiring moderate levels of exertion. Anxiety was measured at baseline and during respirator use with the State-Trait Anxiety Inventory, which measures the more constant anxiety characteristics of the individual (trait anxiety) and the specific level anxiety at the instance of measurement (state anxiety). The participants experienced a 2.92 unit increase (p = 0.01) in state anxiety when using the reusable elastomeric respirator, while there was no effect on state anxiety observed in participants wearing the filtering facepiece respirator (Wu et al., 2011).

Although the evidence is limited, preexisting anxiety may make some users more likely to experience distress while wearing a respirator; however, this has not been sufficiently tested among users of reusable elastomeric respirators in a health care setting. Additionally, Wu and colleagues (2011) comment that the physiological impacts of general respirator use (shortness of breath or overheating) may themselves play a more direct role in instigating an anxiety response among users, and these responses could be mirrored in the use of reusable elastomeric respirators in health care. Given the importance of user compliance and the significant role that psychological responses play in achieving high levels of compliance, respirator design and training should be developed with anxiety reduction in mind (Wu et al., 2011).

Accessibility

The accessibility of reusable elastomeric respirators at the moment they are required by staff is a critical component of compliance with respiratory protection guidelines. However, the availability and accessibility of respiratory protection at the point of care has been cited by health care workers, specifically mobile staff, as a significant barrier to the use of these respirators. TCID and UMMC, both of which use reusable elastomeric respirators, have highlighted the difficulties associated with respirator availability. At UMMC, while the majority of respirator users (94 percent) report that they usually or always have access to their respirator when they need it, as many as 40 percent of this group store their respirator in a location that is not readily accessible or is suboptimal (Hines, 2018). This is especially true of mobile groups such as respiratory therapy staff and medical residents who may travel to multiple units during the day (Hines et al., 2017). Furthermore, these mobile staff members were less likely than non-mobile staff to adhere to reusable elastomeric respirator use (when so designated) and more likely to prefer the use of the more accessible filtering facepiece respirators (Hines et al., 2017; Chang, 2018). Of their experience in Vancouver, British Columbia, the investigators wrote,

Regarding availability, subjects identified challenges in obtaining an EHFR [reusable elastomeric respirator] when doing break relief, having to re-enter the patient room without time to complete the wipe of the EHFR and others noted that since there was an adequate supply of N95 FFRs they did not have to use an EHFR. (Ciconte et al., 2013)

While there are a variety of logistical and storage options available, such as keeping the respirators in a central location such as a nurses station or locker or requiring staff to carry their assigned respirators with them (Radonovich, 2018), no option entirely eliminates issues with accessibility while balancing acceptability. TCID overcame this issue by having respirator users carry their reusable elastomeric respirators with them in a backpack (Kizilbash et al., 2018). However, this requirement has been viewed in other organizations as a nuisance (Hines et al., 2017).

User Perceptions of Protection

Among many users, reusable elastomeric respirators are perceived to be more protective due in part to a perception that it is easier to achieve a good and reliable fit with a reusable elastomeric respirator (Hines et al., 2017). A study of 1,152 health care workers found that users of reusable elastomeric respirators overwhelmingly felt that their respirator protected them well—significantly more than users of filtering facepiece respirators and PAPRs (p = 0.0001). This confidence in the protection provided by their respirator is likely related to the secure fit of the flexible elastomer seal, confidence in the ability to be fit tested, and continued confidence in the ability to achieve a good fit during regular use, as the fit can be easily checked at any time by performing a user seal check. Despite overall dissatisfaction with comfort and communication characteristics, elastomeric respirator users continued to prefer the use of this respirator in certain risk scenarios (Chang, 2018). Reusable elastomeric respirator users did not have different inherent perceptions about specific threats than did users of filtering facepiece respirators (Hines, 2018). Furthermore, support and promotion of the use of reusable elastomeric respirators by the institution was perceived by some workers at UMMC as a demonstration of an institution's commitment to worker safety (Hines et al., 2017).

Patient Perceptions and Visual Aesthetics

Concerns have been raised about patients' perceptions of the use of reusable elastomeric respirators (as well as concerns about perceptions by family members and other visitors); however, there are only limited data available to empirically assess their perceptions of respirator use. There does not appear to be strong evidence of widespread patient anxiety triggered by the use of reusable elastomeric respirators by health care workers. With the 2009 pandemic deployment of reusable elastomeric respirators at the University of Maryland, concerns were expressed that these respirators may cause anxiety, especially among children, as well as among intensive care unit patients with delirium. However, as discussed at the committee's workshop, this fear largely proved to be an unfounded concern, and there were no documented instances where respirator appearance interfered with patient care. The committee could identify only one published article relevant to this topic. Forgie and colleagues (2009) surveyed 80 pediatric patients (ages 4 to 10 years old) and their parents or guardians to ask their preference (through the use of pictures) for care to be provided by a physician wearing a medical mask or by wearing a transparent face shield. Just over half (51 percent) of parents preferred that their child be cared for by physicians wearing a face shield. Sixty-two percent of parents stated that they thought the children would choose a provider wearing a face shield often noting that they thought it would preferable to see the face. The children did not have a strong preference with 49 percent choosing the physicians in the face shields and 39 percent choosing the medical mask. Fifty-nine percent of the children did not find either option frightening. This study provides important initial insights into how patients and their family members perceive the use of protective facial coverings by health care providers.

Decision-Making Process

The need for reusable respirators was identified during pandemic planning for H5N1 avian influenza. Using a conservative model and assumptions, UMMC estimated that it would need almost 400,000 disposable filtering facepiece respirators to protect 1,800 front-line staff for the projected pandemic period of 42 days. Caching this many disposable filtering facepiece respirators was not considered reasonable, and it was thought that the supply chain would not be able to meet this spike in demand. Instead, the organization decided to purchase 1,100 reusable elastomeric respirators with P100 cartridges for its stockpile cache. A number of respirator models were considered using such criteria as ease of fit, comfort, and cartridge selection. The model that was eventually selected was chosen due to its comfortable, fault-tolerant design and the enclosed, low-profile high-efficiency particulate air filter cartridge, versus the traditional open-face cartridge design of other models. The initial purchase cost for the models selected was approximately $19–$33 per respirator and $5–$6.50 per P100 cartridge. The presenter noted to the committee that the use of one reusable elastomeric respirator per health care worker was considered cost effective, as a worker can use an excess of 20 disposable filtering facepiece respirators over the course of one shift (Chang, 2018).

Usage During the H1N1 Pandemic

In March 2009 the first cases of H1N1 pandemic influenza surfaced in the southwest United States and Mexico. By September 2009 supplies of disposable filtering facepiece respirators were extremely limited. When it became apparent that the supply chain was not going to provide sufficient PPE for staff, UMMC began deploying its reusable elastomeric respirator cache preferentially to high-risk units and staff—the medical intensive care unit, the pediatric intensive care unit, emergency departments, respiratory therapists, and other specialties. A cadre of unit-based volunteers, who were trained en masse, performed qualitative fit testing for the new respirators.

Users were provided with instructions for use and with alcohol wipes for facepiece cleaning and were told to store their assigned respirator in a gallon plastic reclosable bag. Protocol required that users wash their assigned respirator weekly. Acceptance of the new respirator was high and undoubtedly influenced by the pandemic. The primary complaint heard from health care workers was the difficulty the patients had in hearing and understanding the provider when wearing the respirator. There were also some concerns that the respirator would be frightening to pediatric patients and disoriented patients; however, these concerns proved largely unfounded (Chang, 2018).

Adherence and Current Usage

As the pandemic situation ameliorated and the supply chain caught up with demand, UMMC elected to continue with the use of reusable elastomeric respirators as its first choice for respiratory protection. This choice was largely due to the perception of greater safety by users, fault-tolerant designs, ease of fit testing, and the ability to do a user seal check (see Table 2-6). Changes were made to the respiratory protection program in response to user requirements (e.g., perioperative users were fit-tested in surgical N95 filtering facepiece respirators). However, concerns regarding the ability of the supply chain to provide adequate stocks of disposable filtering facepiece respirators (and other products) remain (Chang, 2018).

TABLE 2-6

Benefits and Limitations of the Use of Reusable Elastomeric Respirators at the University of Maryland Medical Center.

Currently, respirators in use at the medical center include N95 disposable filtering facepieces as well as reusable elastomeric respirators with P100 or chemical cartridges and PAPRs. However, the medical center is now beginning to shift away from reusable elastomeric respirators as the preferred respiratory protective device because of the burdens of and poor adherence to cleaning and disinfection protocols as well as issues with accessibility for mobile staff (Chang, 2018).

Research on User Acceptance

UMMC recently participated in a research study to assess user acceptance of the reusable elastomeric respirator (Hines et al., 2017). Concurrently, direct feedback on the program from users indicated that mobile staff (staff not assigned to one location such as respiratory therapists and residents) did not travel with their reusable elastomeric respirator and instead were using the nearest available disposable filtering facepiece respirators. Furthermore, manufacturer instructions for cleaning were not consistently followed. As a result, many users were converted to disposable filtering facepiece respirators during their annual fit-testing cycle, and employees new to the UMMC respiratory protection program were provided with disposable filtering facepieces preferentially. Currently, users may continue to opt for reusable elastomeric respirators on a request basis (Chang, 2018).

Decision-Making Process

Prior to 1986, the facility did not have an infection prevention and control program other than annual tuberculin skin testing (TST). The testing showed that 40 to 50 percent of their staff had converted to TST positive after employment, and 1 to 2 percent of staff had TB disease. There were multiple reasons for this high seroconversion rate. Prior to 1995, only medical masks were used for employee protection. In response to the need to better protect its employees, TCID implemented its respiratory protection program in 1995 (Kizilbash et al., 2018). TCID's respiratory protection program evaluated a number of respirator options and settled on a reusable elastomeric respirator (over the use of disposable filtering facepieces) with loose-fitting PAPRs as an alternative option for staff who cannot wear a tight-fitting respirator. Factors that influenced this selection included the perceived reliability, better protection, comfort, cost effectiveness, and ease of fit testing and user seal check experienced with the reusable elastomeric respirators (see Table 2-7). In a comparison of the initial purchase costs, the use of reusable elastomeric respirators was noted as cost effective (approximately $30 to $35 per device) compared to the estimated use of 20 N95 disposable filtering facepieces (approximately $17 for a box of 20) over the course of a single day of patient care. Following the TB test conversion of seven employees in 1992, the facility has not had a TST conversion since 1994.

TABLE 2-7

Benefits and Limitations of the Use of Reusable Elastomeric Respirators at the Texas Center for Infectious Disease.

Adherence and Current Usage

Given the severity of TB and other diseases treated at TCID, adherence to the use of respiratory protection is highly prioritized, and fit testing is available to all employees at all times through the cardiopulmonary department, in addition to the yearly required fit test (Joint Commission, 2014). Of 173 employees working at TCID, 138 wear reusable elastomeric respirators with an N95 cartridge, and two wear PAPRs (Kizilbash et al., 2018). All staff who enter patient rooms are required to undergo respirator qualitative fit testing and training. TCID differs from many other health care centers in that it does not need to select specific clinical staff to undergo fit testing. Additionally, TCID staff carry their assigned respirators with them at all times in a TCID shoulder bag and therefore do not have the same issues with accessibility as described by UMMC and in the Canadian study (Joint Commission, 2014).

Filter cartridges are changed annually or when dirty, saturated with fluids, damaged, or difficult to breathe through (Joint Commission, 2014). Staff are required to leave their assigned respirators at the facility and to wipe the respirators after every use with an alcohol wipe. Cleaning is performed by removing the filter cartridges and submerging the facepiece in a soap and water solution (Kizilbash et al., 2018).

TCID has developed training led by registered nurses that is specific to the hospital's respiratory protection needs. Additionally, the correct usage and maintenance of reusable elastomeric respirators is routinely reinforced among the staff through equipment checks, written testing of infectious disease control knowledge, and documentation of respirator use. TCID reports high staff compliance with respiratory protection program policies, including the correct usage of reusable elastomeric respirators. The effectiveness of the respiratory protection program is evaluated through TB skin test conversions and incidence of active TB infection or other communicable diseases among staff (Joint Commission, 2014; Kizilbash et al., 2018). A summary of the benefits and challenges of elastomeric respirators as identified by TCID staff is provided in Table 2-7.