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3 Designing and Engineering Effective PPE Healthcare workers need to feel confident that the personal protec- tive equipment (PPE) they are being asked to use during an influenza pandemic will be reliable in reducing their risk of infection. Further, the equipment needs to be effective in a work environment that involves in- teraction with and examination of patients and long working hours in a crisis pandemic situation. As discussed in Chapter 1, PPE is one compo- nent of an overall systems approach to infection prevention and control, which during an influenza pandemic will also require environmental and policy measures including vaccination of healthcare workers, use of anti- viral medications, isolation precautions, and ventilation and air exchange controls. This chapter begins by setting out a proposed framework for the de- sign and development of PPE for healthcare workers that will facilitate greater interaction between the end users, designers and manufacturers, and standards and certification agencies. The discussion then focuses on specific research opportunities for enhancing the current generation of PPE and concludes by identifying next steps in the design and develop- ment of PPE. The chapter’s recommendations focus on innovative and systematic approaches to the design and engineering of healthcare PPE. FRAMEWORK FOR PPE DESIGN AND DEVELOPMENT A formal framework for the design and development of PPE encom- passes the three phases typically associated with a product’s life cycle: user requirements analysis, design realization, and field use and evaluation. 77

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78 PREPARING FOR AN INFLUENZA PANDEMIC Key Design Drivers The design and development of PPE are influenced by the key factors shown in Figure 3-1. Since meeting the regulatory standards is manda- tory and not optional, the design and development of PPE often involve major compromises while attempting to simultaneously achieve a maxi- mal degree of protection with the highest level of comfort at the lowest possible cost. For example, the degree of protection provided by protec- tive clothing, such as a gown, can be considerably enhanced by the use of polyethylene film without substantial additional expense, but at a sig- nificant loss of comfort for the user. On the other hand, a high degree of protection and comfort can be achieved, but at a much higher cost, by using a breathable impervious nonwoven material (Pasko, 2007). Thus, although materials and manufacturing technologies exist that can maxi- mize any one design driver, designing the product to achieve the appro- priate balance is ultimately dictated by the requirements of the end user. As will be described in Chapter 4, a number of barriers and reasons have been identified by healthcare workers regarding why they choose not to wear PPE. These reasons include not having enough time to don the equipment (particularly in emergency response situations), the equipment is not available or they have not received training, the equip- ment is uncomfortable or difficult to use, the equipment interferes with their interaction with the patient and affects dexterity or the ability to perform a medical procedure, or they do not see the situation as a high risk. Better guidance is required on the unique needs of healthcare work- ers so that appropriate performance requirements can be developed and Degree of Protection Cost Comfort Regulations FIGURE 3-1 The design drivers for PPE.

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79 DESIGNING AND ENGINEERING EFFECTIVE PPE manufacturers can design and supply PPE to meet the specific needs of this workforce. Moreover, since the design (or solution) space is fairly large, it is possible to produce a large number of variations of the same item of PPE, thereby driving up its cost. By developing PPE based on a prescribed set of evidence-based performance requirements or standards, manufacturers will be able to create products that will be less expensive and more effective; such standards will also enhance compliance in the use of PPE since they will minimize, if not eliminate, the errors typically associated either with the selection of PPE by personnel responsible for PPE procurement in healthcare settings or with its use by healthcare workers themselves. Healthcare workers will be assured that they are receiving the right level of protection in the work- place. To realize this objective, there is a need for a structured design and development process for PPE, as well as thorough testing and certification efforts (Chapter 5). User Requirements Analysis—Data Collection for Design In the first phase of the design and development process, the re- quirements of the end user (i.e., the healthcare worker) should be as- sessed. The first step is to gain an understanding of the hazards and risks associated with the use of PPE in specific environments as well as to un- derstand the barriers to PPE use, particularly in emergency response and crisis situations in patient care (Chapter 4). A clear understanding of the threat will help establish the degree of protection the PPE must meet or exceed. In the case of an influenza pandemic, this calls for an under- standing of the nature of the influenza virus, its infectivity, and its modes of transmission (Chapter 2). A related factor that should be considered is the risk posed by the environment in which the healthcare worker must operate. The continuum of risk is not clearly defined for influenza be- cause so little is known about the routes of transmission of the virus be- tween individuals. Further, the many unknowns concerning the nature and level of infectivity of the influenza virus create challenges for de- signing effective prevention measures. Unlike many industrial exposures for which adverse health effects are the result of exposure to large concentrations of a chemical or other hazardous agent, infectious diseases (such as tuberculosis) may be spread by small numbers of bacilli or viruses.

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80 PREPARING FOR AN INFLUENZA PANDEMIC As discussed in Chapter 4, research is needed that will provide a haz- ard assessment with insights into whether specific procedures or work situations (e.g., nebulization, endotracheal intubation, bronchoscopy, endotracheal suctioning, cleaning patients’ rooms) place healthcare workers at higher levels of risk of influenza infection. According to the 2006 interim guidelines for an influenza pandemic, N95 respirators are recommended for healthcare workers in caring for patients with con- firmed or suspected influenza or in situations, such as bronchoscopy or resuscitation, that are likely to generate infectious respiratory aerosols (CDC, 2006). McCullough and Brosseau (1999) present a qualitative framework for the selection of respirators for the control of worker expo- sure to infectious aerosols, especially in situations where information on occupational exposure limits, toxicity, and airborne concentrations is absent. As stated in Chapter 2, information on the modes of transmission of the influenza virus is scarce and this type of qualitative approach may be valuable in assessing the risk in the healthcare setting during a pan- demic. The authors urge that assessments be conducted by industrial hy- gienists or other trained professionals. In developing evidence-based performance requirements, the ideal data acquisition process would involve use of the PPE component in the field and assessing the requirements; however, in the event this is not feasible, the data acquisition process should, at the very least, simulate the real-world usage of the specific component of the PPE ensemble. For instance, the healthcare worker will sweat during the course of normal day-to-day activities, and this in turn will affect the performance of the PPE—the respirator may change its position on the user’s face or the gown may become increasingly uncomfortable if it does not effectively wick away perspiration from the user’s skin. Therefore, a treadmill or similar method can be used to simulate the use of PPE components to better understand and determine their performance requirements. The next step is to identify the key characteristics that should be con- sidered in the design of the PPE component. As shown in Figure 3-2, these involve considerations of function, use, comfort and wearability, durability, maintenance and reuse, aesthetics, and cost.

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81 DESIGNING AND ENGINEERING EFFECTIVE PPE Evidence-Based Performance Requirements Functionality Usability Comfort and Wearability Durability • Protect against • Maintain biomechanical • Comfortable—no skin • Adequate wear life • Strength—tear, influenza virus efficiency and sense of touch irritation or pressure • Guard against and feel points tensile, burst • Odor-free • Abrasion resistance • Prolonged use contact with • Hypoallergenic • Corrosion contaminated without discomfort • Accommodate wide range of • Breathable—air resistance fluids and aerosols users (face and body profiles) permeable • Compatability across various • Moisture absorbent— elements of the PPE wickability • Low bulk and weight ensemble and with other • Dimensional stabiltiy equipment (e.g., stethoscope) • Non-startling to patients and • Easy to put on and families take off (don and doff) • Facilitates communication with others (verbal, facial) Cost • Product cost Maintenance and Aesthetics • Total life-cycle Reuse • Variety of styles cost • Easy to • Minimal environ- and colors • Customizable decontaminate and mental impact discard disposable elements • Easy to clean and replace parts in reusable PPE FIGURE 3-2 A structured approach to evidence-based performance requirements. For example, protection against the influenza virus and guarding against splashes and contact with bodily fluids are the major functional requirements of PPE. However functionally effective the PPE may be, it is unlikely to be used regularly in the field if the efficiency of the user in carrying out his or her task is impaired by the PPE. PPE should not affect the biomechanical efficiency (work and energy) of healthcare workers, especially since they rely on extensive interaction with the patient and must be able to hear the patient’s respiration and heartbeat, touch and feel the patient’s body, and so on. The PPE should be odor-free and hy- poallergenic and should comfortably fit a variety of body forms includ- ing facial profiles. Its appearance should not startle patients, especially younger children. It should also facilitate verbal and facial communica- tion with patients. User instructions that accompany PPE products should clearly specify appropriate practices to promote their correct usage. In terms of comfort and wearability, the PPE should be comfortable to wear during work activities and should not have any pressure points or cause skin irritation. It should be breathable and have good moisture absorp-

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82 PREPARING FOR AN INFLUENZA PANDEMIC tion. It should be lightweight and have excellent dimensional stability since it will be subjected to extensive stresses and strains during wear. It should be easy to put on and take off (don and doff), especially in a very short period of time. It should be durable, with the wear life depending on the type of ensemble (e.g., gown, respirator), and should be of sound construction to prevent or minimize damage due to tear, tensile, and puncture deformations. Careful consideration should be given to the trade-offs between disposable and reusable PPE, particularly given the extreme demands that would be placed on a disposable PPE supply in an influenza pandemic. Maintenance and reuse are key factors for consid- eration in developing performance requirements (IOM, 2006). Minimiz- ing the environmental impact of PPE cleaning or discard should also be considered. The PPE should be customizable to meet the wearer’s aes- thetic needs including those of style and color. Finally, the product cost and the total life-cycle cost should be specified as part of the require- ments analysis. A similar user requirements analysis process has been employed successfully in the design and development of the Wearable Motherboard or Smart Shirt, an intelligent garment for biomedical moni- toring (Rajamanickam et al., 1998; Park and Jayaraman, 2003). Design Realization—Design and Engineering The second step in the framework is realization of the design by translating the evidence-based performance requirements into the spe- cific design of the PPE component in light of the regulatory requirements as shown in Figure 3-3. This part of the process begins with making appropriate trade-offs between the design drivers of degree of protection, comfort, and cost for the specific PPE component being designed. Once this “degree of protection-comfort-cost” solution space has been established, appro- priate materials and manufacturing processes need to be chosen. For example, the level of required filter efficiency will determine the choice of materials and specific treatments during the manufacturing process for a respirator. Similarly, appropriate finishing treatments should be chosen

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83 DESIGNING AND ENGINEERING EFFECTIVE PPE Evidence-based Manufacturing processes performance requirements FMEA Degree of protection- Field-testing of comfort- cost solution space PPE component Regulations Materials Determines the Define the Results in the selection of Failure modes and effects analysis FIGURE 3-3 PPE design life cycle: evidence-based performance require- ments through field testing. to provide the required degree of thermal comfort for gowns to ensure the comfort of the healthcare workers who are using them. The potential modes of failure of the PPE component in the field should be anticipated and the product suitably designed to guard against such failures. A for- mal failure modes and effects analysis process should be adopted to en- sure the robustness of the resulting design. This process is aimed at proactively identifying where and how equipment and processes might fail and focusing on where changes are needed (IHI, 2007). Field Use and Evaluation: Product in Use As shown in Figure 3-3, and discussed in Chapter 5, in the final phase of the framework, the developed PPE component should be tested and evaluated in the field for a realistic assessment of its performance and to monitor any unintended consequences of use. For respirators, this will necessitate the integration of field testing into the certification proc- ess. During this field testing, the product should be subjected to the vari- ous failure modes identified earlier as part of the FMEA process. Protocols should be put in place to obtain feedback from users during the testing, and these inputs should be used to refine and enhance the design. For example, an ongoing study of the tolerability of various respirators and respirator-mask configurations should provide valuable insights into real-world usage (Radonovich, 2007). Once the product has been placed in service, appropriate mechanisms should be established to obtain continuous feedback on its performance. Programs should be instituted to ensure compliance with the right use of the right PPE for the right level of risk.

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84 PREPARING FOR AN INFLUENZA PANDEMIC In summary, the proposed formal PPE development framework calls for a greater degree of input and collaboration between the various stakeholders associated with PPE—the users (i.e., healthcare workers), the designers and manufacturers, and the regulatory or certification agencies (i.e., the National Institute for Occupational Safety and Health [NIOSH], the Food and Drug Administration [FDA], and the Occupa- tional Safety and Health Administration [OSHA]) responsible for certify- ing and approving PPE. Such a systems and iterative approach will lead to the development and deployment of effective and wearable PPE that can be used in the range of healthcare settings from patients’ homes to hospitals to long-term care facilities. The remainder of this chapter identifies a set of research opportunities to enhance the current genera- tion of PPE and spur the innovations that will result in a new generation of protective equipment. RESPIRATORY PROTECTION: RESEARCH NEEDS The fundamental principle for making decisions regarding the selec- tion and use of respiratory protection is to understand the nature of the hazard and the risks that the wearer is expected to encounter when wear- ing that protection. While there is extensive knowledge regarding the efficacy of respiratory protection, little is known about the extent to which aerosol transmission contributes to the overall risk of infection by the influenza virus. Therefore, the most critical research need regarding respiratory protection for healthcare workers, as discussed in Chapter 2, is accurately defining the modes of transmission of the influenza virus and the likelihood of infection by each route. Lacking this knowledge, the selection and use of appropriate respiratory protection is qualitative and subject to opinions regarding acceptability of risk. Respiratory protection will be necessary in an influenza pandemic if there is a likelihood of aerosol transmission. If properly selected and used, respiratory protection has been demonstrated to significantly re- duce hazardous exposures. However, much of this work has been con- ducted in industrial settings and has focused on chemical exposures. When compared to no respiratory protection, Barnhart and colleagues (1997) estimated that the use of respiratory protection reduces risks of skin test conversion for tuberculosis by the following proportions: surgi- cal mask, 2.4-fold; disposable dust, fume, mist, or high-efficiency par- ticulate air filtering (HEPA) mask, 17.5-fold; elastomeric HEPA

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85 DESIGNING AND ENGINEERING EFFECTIVE PPE cartridge respirator, 45.5-fold; or powered air-purifying respirator (PAPR),1 238-fold. Teleman and colleagues (2004) found that the consis- tent use of N95 filtering facepiece respirators by healthcare workers for contact with severe acute respiratory syndrome (SARS) patients was strongly protective regarding risk of SARS infection (OR [odds ratio] 0.1, 95% CI [confidence interval] 0.02 to 0.86). A limited number of studies have looked at the effectiveness of PPE in other infectious dis- ease situations (Table 1-4). As discussed in Chapter 1, NIOSH has authority to define the con- struction and performance of respirators and to certify respirators for use that meet those requirements (NIOSH, 2004a); OSHA regulates the use of respirators in the workplace (OSHA, 1998). The FDA has regulatory authority to provide manufacturers with the approval to market respirators and other PPE (e.g., gowns, gloves) that will be used in patient care. Additionally, the American National Standards Institute (ANSI) has issued a consensus standard on the use of respira- tory equipment that is relevant to the use of respirators in the healthcare setting (ANSI, 2001). Respirators approved by NIOSH for protection from aerosols are broadly categorized by whether they are air purifying or air supplying.2 The types of respirators that have been designated for use against in- fluenza (CDC, 2006; OSHA, 2007b) are negative-pressure3 air-purifying respirators or PAPRs. For negative-pressure air-purifying respirators, the level of protection from aerosol exposure is primarily a function of leak- age through the faceseal due to the negative pressure created inside the facepiece of these respirators when the wearer inhales. Penetration may also occur through the respirator filter media. For a PAPR, the level of protection is primarily a function of the flow rate of air into the facepiece and secondarily of the efficiency of the filter. Respirators worn by healthcare workers will not only protect them, but may also reduce the spread of disease from one patient to another (via the healthcare worker) or from an infected but asymptomatic healthcare worker. Determining whether exhaled air from workers needs to be filtered is a critical re- 1 In this report, the term PAPR is used to refer to loose-fitting devices unless otherwise specified. 2 Air-purifying respirators use a filter, cartridge, or canister to remove air contaminants (ambient air passes through the air-purifying element). Air-supplying respirators supply the user with breathable air from a source independent of the ambient air (OSHA, 2007a). 3 Air pressure inside the facepiece during inhalation is lower than the ambient air pres- sure; this allows air to flow through the filter and into the facepiece.

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86 PREPARING FOR AN INFLUENZA PANDEMIC search item. For filtering facepieces, this is accomplished by the elimina- tion of an exhalation valve, but there is no current solution for PAPRs. Medical masks are not designed to offer respiratory protection to the wearer (Chapter 1). These masks protect patients from droplets in the wearer’s exhaled breath and are not intended to fit tightly on the wearer’s face or to be constructed of high-efficiency filter media. Medical masks may serve to provide a barrier to infectious droplets but are not consid- ered respiratory protection. In the aftermath of the SARS outbreaks, re- searchers have conducted several studies to examine the level of protection that medical masks may provide to the wearer (for example, Balazy et al., 2006b; Li et al., 2006b). Further research is needed to clar- ify the role of medical masks in providing barrier protection during an influenza pandemic as these masks are widely available and will be ac- cessible to healthcare workers and to the general public. Enhancing the Fit Faceseal leakage is the most critical factor in the ability of a respira- tor to protect the wearer from exposure to airborne contaminants. OSHA requires that respirators be qualitatively or quantitatively fit tested before they are used (OSHA, 1998). Three important components of a respira- tory protection program are selecting the right size and shape for the wearer’s face, confirming fit by testing, and proper and consistent use of the respirator when worn. The fit factor (FF) is the fundamental parame- ter describing the effectiveness of the quality of the seal between the res- pirator and the wearer’s face and is defined as the reciprocal of the fraction of the contaminant concentration entering a respirator through leaks. The fit factor is measured and determined by fit testing, which can be conducted using quantitative or qualitative methods. Qualitative methods rely on the wearer to detect the presence of the challenge agent inside the respirator by smell or taste. Quantitative testing methods measure the amount of leakage of the contaminant into the respirator facepiece and include test aerosol, ambient aerosol, and dynamic nega- tive-pressure tests. Filtering facepiece and half-mask respirators can be tested by both methods. However, full-face respirators and tight-fitting PAPRs must be tested by quantitative methods. Fit testing and training on how to don, wear, and doff a respirator have been shown to increase the protection provided by the respirator while in use. One-on-one and classroom training significantly increase fit test pass rates compared to no training at all (Hannum et al., 1996).

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87 DESIGNING AND ENGINEERING EFFECTIVE PPE After conducting aerosol ventilation studies using technetium-99 (99mTc), Huff and colleagues (1994) found that personnel wearing fit-tested respi- rators had significantly lower counts from radiation contamination (disin- tegrations per minute) on nasal swabs than those wearing respirators that were not fit tested or medical masks. Other studies have shown that fit testing increases simulated workplace protection factors for elastomeric and filtering facepiece respirators (Coffey et al., 1999, 2004; Lawrence et al., 2006). In focus group discussions, healthcare workers during the SARS outbreaks expressed concerns about the variability be- tween fit testing and training methods used by different healthcare facili- ties (Yassi et al., 2004). Increased standardization of fit testing and training methods should be explored as should simpler, more efficient methods of fit testing. In use, the efficacy of the faceseal can vary greatly and may not nec- essarily be related to the fit factor as determined by fit testing. The mini- mum acceptable level of fit under these use conditions is the assigned protection factor (APF). The APF is defined as the anticipated level of protection provided by the respirator (based on supplying properly fitted and functioning respirators to a given percentage of trained users) (Bollinger, 2004). APFs are based on the analysis of workplace protec- tion factor (WPF) and simulated workplace protection factor (SWPF) studies (Coffey et al., 2004); the higher the APF value, the greater is the expected level of respiratory protection. OSHA, NIOSH, and ANSI have defined APFs for classes of respirators based on facepiece type and res- piratory inlet covering (Table 3-1; OSHA, 2006). The actual level of protection provided by respirators when worn un- der various work conditions is measured by the total inward leakage (TIL). This is the sum of the leakage through filters, respirator compo- nents (exhalation valves), and faceseals—faceseal leakage being the most critical and variable factor. The TIL for various models within a respirator class or type has been shown to vary significantly, and some models have measured penetration values greater than 10 percent. Coffey and colleagues (1999) found significant variation in SWPFs of 21 N95 filtering facepiece respirators. Similarly, a study of 18 N95 filtering facepiece respirators found that 5th percentile SWPFs without fit testing ranged from 1.3 (indicating virtually no protection) to 48.0; fit testing was found to increase protection (Coffey et al., 2004). A TIL study using a standard European test method (EN 13274-1) found that half-mask elastomeric facepiece respirators had less leakage than filtering facepiece respirators and that leakage was significantly different between classes of

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102 PREPARING FOR AN INFLUENZA PANDEMIC Currently, fit testing is a critical requirement for ensuring the efficacy of respirators. However, it may not always be complied with for various reasons, including time and cost. Moreover, current methods preclude the fit testing of individuals with facial hair, and respirators are not designed specifically for young children. Therefore, the use of shape memory polymers in the design of respirators should be investigated to enhance ease of fit and comfort and potentially to minimize fit testing. A short- term goal should be to develop respirators that would be easy to fit, while a longer-term goal should be to find a way to obviate the need for fit test- ing of respirators while being efficacious for all individuals. Chemical Treatments on PPE with Biocidal Properties There are times when the fit of a respirator is compromised and pathogens can gain entry to the face (Li et al., 2006a). Moreover, the pro- tective effect of N95 respirators and medical masks is maintained only when the surface layer is hydrophobic and dry. Therefore, when the PPE is wetted, protection is reduced significantly. Also, if the surface is con- taminated with infectious agents, pathogens may penetrate the protective layers along with the droplets. The use of biocidal compounds as coatings for PPE is being explored (Sun and Xu, 1998; Li et al., 2006a). Li and colleagues (2006a) have de- veloped an antimicrobial nanoparticle coating from a mixture of silver nitrate and titanium dioxide and demonstrated its effectiveness against common hospital pathogens. In addition, Baker and colleagues (2005) have demonstrated that complete cytotoxicity to bacteria cells was possi- ble at low concentrations of silver nanoparticles. These promising studies highlight the value of such finishing treatments in enhancing the protec- tion afforded by PPE to healthcare workers. Therefore, research should be directed to investigate the use of chemical treatments (e.g., using nanoparticles) to impart biocidal properties to PPE to enhance their pro- tection capability and possibly extend their useful life. User safety is the primary consideration; testing standards will be needed to ensure that biocidal materials do not pose hazards to PPE wearers.

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103 DESIGNING AND ENGINEERING EFFECTIVE PPE OPPORTUNITIES FOR ACTION As discussed throughout this chapter, there are a number of areas in which research is needed to improve the wearability, functionality, and other critical aspects of healthcare PPE. The committee has identified several key actions that if addressed expeditiously (in the next 6 to 12 months) could have a significant impact on improving the nation’s readi- ness for pandemic influenza; longer-term opportunities and research questions abound and need to be explored for improving healthcare PPE products so that they can be used more effectively, with greater ease and comfort, and for longer periods of time. Immediate Opportunities There is an immediate need to examine the design of PPE for health- care workers, to improve coordination and expedite approval, and to un- derstand the efficacy of various decontamination techniques (e.g., bleach, microwave radiation, ultraviolet light) that could be employed on PPE in a healthcare setting. Questions of interest include the following: • For what period of time does PPE remain contaminated with in- fectious influenza viruses, and what improvements can be made in doff- ing and decontamination procedures given that information? What are the appropriate PPE decontamination strategies that would not compro- mise the integrity of the PPE while being easy and cost-effective to im- plement in a healthcare setting? • What are the differences in protection of N95 versus N100 or other respirators if exposed to human and avian influenza aerosols? • Current PAPRs are designed to provide extremely high flow rates to protect the worker in an industrial setting. While appropriate to protect from significant dust exposures, they present serious design im- pediments for the healthcare worker. What are the flow rates and maxi- mum noise levels that would be required for NIOSH to certify a PAPR that would provide adequate protection for healthcare workers? What is the risk to patients from healthcare workers wearing PAPRs (from unfil- tered exhaled air), and what design modifications would be needed to eliminate such risk as well as facilitate interactions with patients? • Could a nondisposable respirator be designed that could be eas- ily decontaminated and cost-effective?

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104 PREPARING FOR AN INFLUENZA PANDEMIC • What immediate systemic or strategic measures can be taken to facilitate closer collaboration between healthcare workers (end users), PPE manufacturers, and certification or regulatory agencies on the design and development of PPE for healthcare? Long-Term Key Research Needs • What protective roles do gloves, gowns, and face shields or other eye protection play in preventing influenza transmission? What protec- tion would medical masks provide to the wearer during an influenza pandemic? • Do specific procedures (e.g., nebulization, endotracheal intuba- tion, bronchoscopy, cleaning of patients’ rooms) place healthcare work- ers at higher levels of risk of influenza infection? To what extent do various types of PPE offer protection during these procedures and processes? • What technologies can improve fit to circumvent the need for fit testing? • What innovative designs can improve wearability issues regard- ing PPE? • Can the protection levels of the PPE worn by healthcare workers (e.g., N95 respirators) be continuously monitored during use to provide an alert to change the PPE when it is no longer effective? • How does the penetration risk of N95 respirators made of differ- ent materials and designs change with high inhalation rates? • How does the level of protection afforded by N95 change with and without fit testing? • What is the impact of masking influenza patients on transmission risk? If effective, how long before the medical mask needs to be changed? • What are the best practices for PPE removal to minimize risk of self-inoculation? • What are the risks of self-inoculation when changing PPE (i.e., is the true acquisition risk the same when wearing a medical mask and changing to an N95 for high-risk procedures versus wearing an N95 throughout the shift)?

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105 DESIGNING AND ENGINEERING EFFECTIVE PPE SUMMARY AND RECOMMENDATIONS Healthcare workers need PPE that provides protection against influ- enza transmission and that can be worn while working without adding undue physiological burdens. Designing and engineering effective PPE that will meet the needs of healthcare workers during an influenza pan- demic will require careful consideration of three key factors: protection, cost, and comfort, while also achieving certification and approval criteria established by FDA, NIOSH, and other relevant agencies and organiza- tions. Critical to the design and development of PPE are a more thorough understanding of the threats posed by the influenza virus (see Chapter 2) and greater engagement of healthcare workers in the design and testing processes to provide information on the risks and the workplace envi- ronment. Innovative designs and materials are needed for the next gen- eration of PPE for healthcare workers. For respirators, the filter and the faceseal are the critical issues; other types of PPE provide barrier protec- tion and require innovations particularly regarding the interface between PPE (e.g., between eye protection and respirators). The development of design and performance standards is envisioned as an iterative process that will lead to more effective and wearable PPE products based on evolving technologies and feedback from all stake- holders including data from researchers on the transmission of influenza and input from healthcare workers on performance requirements. Based on an in-depth analysis of the design and engineering of effective PPE for healthcare workers, the committee has developed the following set of recommendations: Recommendation 2 Define Evidence-Based Performance Re- quirements (Prescriptive Standards) for PPE NIOSH, through the National Personal Protective Technology Laboratory (NPPTL), in collaboration with extramural re- searchers, manufacturers, and regulatory agencies, should de- fine a set of evidence-based performance requirements or prescriptive standards for PPE to facilitate their design and development that optimally balances the cost, comfort, and degree of protection of PPE and enhances compliance with their use in the field.

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106 PREPARING FOR AN INFLUENZA PANDEMIC Recommendation 3 Adopt a Systems Approach to the Design and Development of PPE NIOSH should promote a systems approach to the design, de- velopment, testing, and certification of PPE using evidence- based performance requirements or prescriptive standards and fostering closer collaboration between users, manufac- turers, and research and regulatory agencies. Recommendation 4 Increase Research on the Design and En- gineering of the Next Generation of PPE NIOSH, the Department of Homeland Security, the Depart- ment of Defense, manufacturers, and other relevant organiza- tions and agencies should fund research directed at the design and development of the next generation of respirators, gowns, gloves, and eye protection for healthcare workers that would enhance their safety and comfort by • utilizing innovations in materials such as shape mem- ory polymers (e.g., to obviate fit testing and enhance fit of respirators and comfort of gowns) and finishing treatments (e.g., safe antimicrobial or biocidal finishes); • developing more effective and consistent faceseals for respirators, including examination of the effect of wear and repeated donning and doffing on the qual- ity of the faceseal of filtering facepiece respirators, and research on the effect of respirator filter effi- ciency on faceseal leakage and degree of protection; • providing a seamless interface between PPE (e.g., eye protection and respirators); • designing respirator facepieces to integrate medical devices such as a stethoscope and to improve commu- nication between the user and others; • establishing a new set of performance requirements for PAPRs and for reusable filtering facepiece respi- rators that meet the needs of healthcare workers; and • incorporating sensors into PPE to detect breaches and notify users of end of service life and other pro- tection information.

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107 DESIGNING AND ENGINEERING EFFECTIVE PPE Recommendation 5 Establish Measures to Assess and Compare the Effectiveness of PPE NIOSH, through NPPTL, should develop and promote a vali- dated set of measures for comparing the effectiveness of PPE products. The goal is a set of measures that would allow users to compare and select appropriate PPE commensurate with the assessed risk and desired level of protection. Particu- lar attention should be paid to disseminating information to healthcare workers on PPE effectiveness relevant to influenza. These efforts require: • expedited efforts to finalize a standardized method for measuring the total inward leakage of respirators as part of the NIOSH respirator approval protocols; • clear measures of filter efficiency; and • clear measures for comparing the effectiveness of respirators, gowns, gloves, eye protection, and other types of PPE based on evidence-based performance requirements. REFERENCES ANSI (American National Standards Institute). 2001. ANSI Z88.2—American national standard for respiratory protection. Washington, DC: ANSI. Baker, C., A. Pradhan, L. Pakstis, D. J. Pochan, and S. I. Shah. 2005. Synthesis and antibacterial properties of silver nanoparticles. Journal of Nanoscience and Nanotechnology 5(2):244-249. Balazy, A., M. Toivola, T. Reponen, A. Podgorski, A. Zimmer, and S. A. Grinshpun. 2006a. Manikin-based performance evaluation of N95 filtering- facepiece respirators challenged with nanoparticles. Annals of Occupational Hygiene 50(3):259-269. Balazy, A., M. Toivola, A. Adhikari, S. K. Sivasubramani, T. Reponen, and S. A. Grinshpun. 2006b. Do N95 respirators provide 95% protection level against airborne viruses, and how adequate are surgical masks? American Journal of Infection Control 34(2):51-57. Barnhart, S., L. Sheppard, N. Beaudet, B. Stover, and J. Balmes. 1997. Tubercu- losis in health care settings and the estimated benefits of engineering controls and respiratory protection. Journal of Occupational and Environmental Medicine 39(9):849-854.

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