The workshop opened with presentations that defined and described powered air purifying respirators (PAPRs) and the current regulatory landscape influencing PAPR design and use. In general, PAPRs can be described as respirators that protect the user by filtering out contaminants in the air and use a battery-operated blower to provide the user with clean air through a tight-fitting respirator, a loose-fitting hood, or a helmet. Use of tight-fitting PAPRs (see Figure 2-1) requires fit testing; use of loose-fitting PAPRs (see Figure 2-2) does not require fit testing.1
The Occupational Safety and Health Administration (OSHA) provides a functional definition of a PAPR as “an air-purifying respirator that uses a blower to force the ambient air through air-purifying elements to the inlet covering” (29 CFR 1910.134(b)). The National Institute for Occupational Safety and Health (NIOSH) definition of PAPRs describes the components in a PAPR—a facepiece, hood, or helmet; a breathing tube; a canister or cartridge with filter; and a blower (42 CFR 84.2(z)).
NIOSH CERTIFICATION STANDARDS
Roland Berry Ann
National Personal Protective Technology Laboratory
OSHA regulates workplace implementation of respiratory protection programs (29 CFR 1910.134) and requires that all respirators used in OSHA-regulated workplaces be certified by NIOSH (42 CFR Part 84).
1Workshop speakers in most cases did not specify the type of PAPR they were talking about, but as depicted in their slides and descriptions, loose-fitting PAPRs were the type that were primarily discussed during the workshop.
FIGURE 2-1 Examples of tight-fitting powered air purifying respirators.
SOURCE: OSHA, 2011.
FIGURE 2-2 Examples of loose-fitting powered air purifying respirators.
SOURCE: OSHA, 2009.
Federal regulations delineate U.S. respirator performance standards (see Box 2-1). Through the National Personal Protective Technology Laboratory (NPPTL), NIOSH tests and certifies that PAPRs and other respirators meet these standards. Among other requirements, NIOSH PAPR testing includes an assessment of airflow, that measures
- Minimum airflow rate: A tight-fitting PAPR must provide a constant airflow of 115 liters per minute; a loose-fitting PAPR must provide 170 liters per minute.
- Maximal operation flow rate: Tests are done for 4 hours of continuous operation with the given PAPR being set for maximal operational flow, which could be up to 250 liters per minute.
- Specific characteristics such as inhalation and exhalation resistance.
One part of NIOSH’s certification testing for PAPR filters is a silica dust loading test, which is a method used to test for filter effectiveness in work conditions found in industrial settings, principally mining. Mining activities typically expose workers to dusty conditions and require workers to engage in moderate to high physical exertion rates, which means that respirators used in these settings must have high airflow rates to meet worker breathing demands. These workplace environments and
U.S. Regulatory Structure for Respirator Certification
The National Institute for Occupational Safety and Health (NIOSH), within the Centers for Disease Control and Prevention of the Department of Health and Human Services, administers regulations for the certification of respiratory protective devices (42 CFR Part 84). For respirators used in mine rescue operations and other mine emergencies, this administrative authority is jointly held with the Department of Labor’s Mine Safety and Health Administration.
42 CFR Part 84 specifies minimum mandatory requirements. Sub-parts A through G of this regulation provide general information and requirements applicable to all respirator types. Included are such topics as application procedures, fees, certificates of approval and disapproval, quality assurance, the classification of approved respirators, and general construction requirements. In addition, subparts H through L and N define minimum design, performance, and test requirements for various devices that provide respiratory protection for fixed periods of time against hazards specified in the certificate of approval.
Common types of respirators certified by NIOSH include self-contained breathing apparatus (subpart H), gas mask air purifying respirators (subpart I), supplied-air respirators (subpart J), air purifying particulate respirators (subpart K), chemical cartridge air purifying respirators (subpart L), powered air purifying respirators (PAPRs) (subparts G, I, L, KK), and special use respirators such as vinyl chloride respirators (subpart N). For respirators that provide combined protections (such as for gas, vapor, and particulates), portions of individual subparts apply.
conditions differ from those experienced by health care personnel, and therefore it may be necessary to reexamine the requirements and testing processes for certifying PAPRs to be used in health care settings.
NIOSH has the regulatory flexibility under existing authorities to certify PAPRs that have different performance characteristics than those currently in place. For example, NIOSH has made changes to its certification standards in response to a request to approve a breath-response PAPR. This type of PAPR does not have a constant flow rate, but rather it adjusts to the wearer’s breathing rate (the greater the demand, the higher the rate of air supply). After developing an appropriate test, NIOSH defined and approved the breath-response PAPR as a new class of PAPR (42 CFR 84.60 and 42 CFR 84.63).
In the future, the performance requirements and certification standards for PAPRs used in health care settings could be altered to account for the light-to-moderate exertion requirements of health care workers. Berry Ann suggested that potential next steps for PAPRs for health care could include
- Assessing the potential for a new respirator class structure that would meet different performance requirements;
- Developing strategies for the selection and use of PAPRs with alternate flow-rate levels that could match the respiratory needs of various types of health care workers and could address comfort and tolerability concerns;
- Conducting workplace studies to determine the work exertion rates for different types of health care workers and settings as well as the “net effect of alternative PAPR flow rates on health care worker protection”; and
- Assessing the International Organization for Standardization (ISO) requirements for respiratory protective devices to see if they could be used to inform improvements in NIOSH regulations.
Additionally, workplace studies and improved regulations might enable the development of new products that better “match the capabilities to the user’s needs.”
Deborah Gold, Cal/OSHA
California has 1 of 22 OSHA state plans that cover both public-sector and private-sector workers. State plans must include respiratory protections for workers that are at least as effective as those required by OSHA. California’s Division of Occupational Safety and Health Administration (Cal/OSHA) regulations affecting PAPR use in health care focus on multiple areas:
- Chemical exposure: These standards include permissible exposure limits for various substances, such as formaldehyde, ethylene oxide, and glutaraldehyde. They require the use of respirators to reduce exposure if exposure is not reduced by other means. These standards for respiratory protection programs address program administration, respirator selection, training, medical evaluation, fit testing, and use.
- Blood-borne pathogens: Full facepiece PAPRs and some loose-fitting PAPRs provide face and eye protection against bodily fluids as required by the standard regarding blood-borne pathogens.
- Aerosol-transmissible disease: This California standard generally requires the use of NIOSH-approved respirators for respiratory protection in providing care to patients who are suspected of or confirmed to have an airborne infectious disease.2 The standard requires respiratory protection for novel or unknown pathogens and those for which California’s public health agencies recommend airborne infection isolation. The standard also requires, with some exceptions, the use of PAPRs for high-hazard procedures (such as sputum induction, administration of aerosolized medications, bronchoscopy, and pulmonary function testing) that may involve airborne infectious diseases or aerosol transmissible pathogens.3
2Infectious diseases identified by the Centers for Disease Control and Prevention’s Healthcare Infection Control Practices Advisory Committee that require airborne infection isolation include tuberculosis, severe acute respiratory syndrome (SARS), measles, and varicella.
3California’s Occupational Safety and Health Administration Standards Board adopted this standard in 2009 after a 6-year regulatory development project that included 10 formal public advisory meetings.
Under Cal/OSHA regulations, PAPRs are specified for high-hazard procedures because they can offer assigned protection factors (APFs)4 ranging from 25 to 1,000, which reduce the risk more than the protection factors provided by N95 respirators.5 The improved protection is largely provided by the positive pressure in the head covering or facepiece. PAPRs with loose-fitting hoods provide additional potential advantages in that they do not need to be fit tested and they can be used by health care workers for whom an acceptable seal cannot be achieved due to facial hair or other factors. The hoods of PAPRs can provide splash protection and some degree of eye protection, and some workers have reported that the airflow can keep the shield from fogging and can reduce heat buildup. In the agency’s experience, there have been fewer equipment shortages for PAPRs than for disposable N95 respirators.
The most common concern Cal/OSHA receives regarding the use of PAPRs has been their effect on the sterile field, such as during surgery, as PAPRs do not filter the discharged air. Some health care facilities have tried using surgical masks under the loose-fitting head coverings or placing the ends of the PAPR hood under the surgical gown, but neither is a tested or certified configuration. There appears to be little reliable information on infection risks from using a standard surgical ensemble, which includes a surgical cap and facemask, compared to the risks from using a PAPR, nor is there much information about how those risks can be reduced. Another concern with PAPRs is the vulnerability of the external connections, such as hoses, cords, and filters, which may become dislodged in congested emergency environments where many people may be moving quickly. Concerns have also been raised about the level of protection that is achieved and the ability of the PAPR to remain in place in different work postures, such as when workers need to bend or stoop to provide care. Challenges in disinfecting the external working parts as workers move from patient to patient were also noted. Additionally, some health care institutions may not provide training for those who use loose-fitting PAPRs because often respiratory protection training is
4The assigned protection factor (APF) of a respirator denotes the level of protection that the respirator is expected to provide to users who are properly fitted and trained. For example, an APF of 10 “means that a user could expect to inhale no more than one tenth of the airborne contaminant present” (OSHA, 2014).
5N95 particulate filtering facepiece respirators filter at least 95 percent of airborne particles and have APF of 10. In addition to certification by NIOSH, some N95 respirators have also been cleared by the Food and Drug Administration to meet additional requirements; these are called surgical N95 respirators.
conducted in the same session as a fit test, and for these types of PAPRS a fit test is not required.
Gold said that she has found that employers and employees support PAPR use when the PAPRs are part of a well-devised respiratory protection program. The deployment of PAPRs has been carried out in various ways. One hospital in California set up a program in which the hospital’s central supply, on request, sends a PAPR system to the designated patient care unit. The system, which is on a rolling rack, includes multiple PAPRs and charging stations, a place to put each individual worker’s head covering, disposable items, and equipment for disinfection between uses. When the PAPR is no longer needed, it is returned to central supply for reprocessing, including decontamination and disinfection. Other hospitals have equipped airborne infection isolation rooms with multiple PAPRs, batteries, charging stations, and disinfecting equipment. The equipment is maintained during maintenance rounds. Some hospitals maintain PAPRs in respiratory therapy or similar units. Successful programs are those in which all affected workers are trained on how to use the PAPRs, with the training refreshed periodically and reinforced by unit-based champions for PAPR use. However, PAPRs are often not used in cases where the onus is on the individual health care worker to request the PAPR and there are no effective procedures to mobilize the resource.
“We need NPPTL to develop criteria that satisfy infection control goals as well as employee protection in order for these respirators to be broadly accepted in health care,” stated Gold. She continued by saying that improvements to PAPRs and PAPR certification for use by health care workers should consider the following issues:
- Examine and define the impact of various PAPR designs on infection prevention. Questions include
- Can PAPR design be improved to direct and/or filter exhaust air?
- What is the standard of filtration that a PAPR should be expected to meet for discharged air? For example, many existing surgical masks do not provide a high level of filtration.
- What are the appropriate procedures for the disinfection of PAPR components? Which components need to be disposable?
- Aim for an APF higher than 25 for common health care PAPRs while increasing usability, and provide information on the
- specific APF range as confirmed by NIOSH in the respirator certification. A higher level of respiratory protection needs to be available for aerosol-generating procedures and for exposure to more hazardous pathogens.
- Include durability criteria in PAPR certification, such as the ability of the device to maintain configuration, flow, and protection in different postures. At a minimum, PAPRs should have a label stating for which postures they have been certified for use.
- Written materials included with respirator certification should have clear, plainly written statements to facilitate employer selection and employee training on the use, advantages, and limitations of specific equipment. Distinctions between different types of respirators need to be made.
ISO RESPIRATORY PROTECTIVE DEVICE STANDARDS
Craig Colton, 3M
In 2001, the ISO Technical Committee on Personal Safety—Protective Clothing and Equipment (TC94) formed a subcommittee (SC15) to develop ISO standards for respiratory protective devices. The American National Standards Institute, through an accredited technical advisory group administered by NIOSH, represents the United States on ISO SC15, which develops standards for filtering devices (including PAPRs) dependent on the ambient atmosphere (as opposed to respirators that supply breathable gas independent of the ambient atmosphere).
In the United States, respirators are classified based on the type of device (e.g., half-facepiece, PAPR or full facepiece, PAPR). By contrast, ISO standards classify respirators based on performance criteria (see Table 2-1). When considering whether NIOSH should adopt a regulatory framework that better parallels ISO classifications, Colton suggested that manufacturers would argue for performance specifications rather than design specifications to allow them to develop a PAPR that can do what it needs to do. ISO assigns respiratory protective devices to one of six classes based on the results of a total inward leakage (TIL) test.6 One of
6In the TIL test, a person wears the PAPR in a chamber into which particulates (such as sodium chloride) are introduced at a specific concentration. The particle levels inside the PAPR are compared with the particle levels in the chamber to determine the total
TABLE 2-1 Comparison of Key Differences Between Current Standards and Proposed ISO Standards
|Current NIOSH/European Union (EU) Standards||Proposed ISO Standards|
|Basic classification||Type||Total inward leakage (TIL) laboratory test|
|Work rates||Not classified: some validation (e.g., firefighting SCBA)||Four work rate classes|
|Particle filters||NIOSH: 9 particle filters EU: ~6 particle filters||Potential for 20 particle filters (four work rates, each with five efficiencies)|
|Gas and vapor||Classified by capacity||Classified by capacity and work rate|
|Selection and use||Varies by region or country but generally based on protection factors||Based on ISO classification, the protection level is linked to the TIL|
NOTES: ISO = International Organization for Standardization; NIOSH = The National Institute for Occupational Safety and Health; SCBA = Self-contained breathing apparatus.
the areas needing further exploration is the correlation between how a device performs in the TIL test and how it performs in real work experiences. For health care settings, it will be important to know the level of airflow needed to determine an acceptable protection level for work in that setting.
One of the major ISO performance requirements for a respirator is based on the work rate that the respirator is designed to support. Proposed ISO standards include four ISO work rate classifications, with the
inward leakage of the respirator; the TIL level is then extrapolated to set the protection level.
W1 work rate classification covering approximately 90 percent of industrial workplaces. The work rate represents the level of airflow that is needed by the worker to meet the job requirements. A manufacturer can, therefore, design a PAPR to meet desired performance criteria. However, for many workplaces, including health care settings, much remains to be learned about work rate classification.
Another way in which ISO classifies respirators is by the respiratory interface—how much of the face or the nose and mouth area the respirator covers and the respirator’s fit (tight or loose). Using ISO classifications, similar-looking devices could have different levels of protection, and devices that appear different could have similar classifications—a PAPR could be classified the same as a half-mask respirator, for example, if the TIL test performance is the same.
Filters are classified by ISO based on performance, work rate class, and whether they are usable for only a single work shift or are reusable. Whereas NIOSH has 9 particle filter categories, ISO has some 20 options. Special applications also are considered in the classification (e.g., mining operations, firefighting, CBRN [chemical, biological, radiological, and nuclear]), and there are requirements for respiratory protection device noise levels and for warning indicators for battery life and airflow. NIOSH uses a silica dust loading test for PAPR certification, but this may not be relevant to the health care setting.
DISCUSSION ON STANDARDS AND REGULATION
The discussion among the workshop participants focused on four major issues: (1) acceptable protection levels and how these levels should be determined for health care workers, (2) performance criteria and the determination of the protection factors of PAPRs, (3) the extent to which ISO standards can be incorporated into U.S. regulatory standards, and (4) the specific needs for health care PAPRs and health care workers using PAPRs.
First, health care workers face a variety of pathogens and hazards, which affect acceptable protection levels for PAPRs. Lewis Radonovich, Department of Veterans Affairs, noted that upper thresholds for acceptable exposure levels have not been set, and setting those limits would be difficult because so little is known about the necessary inoculum size for respiratory viruses to cause infection. He also suggested that discussion is needed about which exposure levels are acceptable and achievable.
Second, more information is needed to determine whether PAPR performance criteria translate to appropriate protection factors in practice. For example, does a device’s acceptable amount of inward leakage (which determines the protection factor) protect workers against a highly infectious disease? Richard Metzler, NPPTL, remarked that research is needed on how the laboratory TIL test relates to the performance of a PAPR in real-life workplaces. Stating that it is important to understand the level of protection needed and the workplace performance requirements in order to assess lower flow rate products, Metzler also commented that further efforts are needed to determine if the TIL test used in Europe is “equivalent to and predictive in a manner that OSHA’s assigned protection factors are.” OSHA has determined APFs that apply to all respirators of a specific type or class (e.g., the APF for loose-fitting PAPRs is 25 and for full facepiece tight-fitting PAPRs is 1,000); ISO standards would base the protection factor on the results of the TIL tests for a specific product.
Third, the extent to which ISO standards can be incorporated into U.S. regulatory standards remains unclear. Bill Kojola questioned how the ISO approach would work with OSHA’s respiratory protection programs and wondered if the approach would help or hinder respirator selection by employers. Would it be confusing to employers? Maryann D’Alessandro noted that NPPTL is taking a modular approach to the incorporation of the ISO standards and will start with PAPR-related standards. Metzler stated that selection and industrial hygiene issues are being carefully examined and that ISO standards could lead to different APFs within a specific class of respirator.7 Dan Shipp, International Safety Equipment Association, noted that the ISO standards would require a much different approach to certification testing. He added that currently NIOSH certifies respirators as a complete unit (rather than by performance of their component parts) with tests and standards for the nine different classifications of respirators, but it will be challenging to move to a certification system that could have 40 different combinations of work rates, filter efficiencies, and other performance measures.
Colleen Miller, NPPTL, noted that NPPTL is building TIL testing chambers according to the ISO standards. The TIL tests will involve three different challenges: corn oil, which is also used for CBRN respirators; sodium chloride aerosol; and a sulfur hexafluoride challenge for respirators that may be tight-fitting but have some kind of a porous barri-
7Currently, all half-mask respirators have an APF of 10.
er that needs to be evaluated. NPPTL also is exploring other new respirator tests, including a breathing test to develop work rate classes.
Fourth, health care workers may have special needs that should be considered when designing regulations for PAPRs used in health care settings. While PAPRs are not recommended for use during surgery, Gold noted that some surgical teams would like to use PAPRs but there are concerns that the unfiltered exhaust from the respirator might contaminate the sterile field. She added that NIOSH could provide leadership in this area by examining how to assess the contamination of the sterile field and standards regarding air exhaust. Larry Green, Syntech International, commented that surgical helmet systems have filtration systems for the exhaust air but that these systems are not approved for employee respiratory protection. Gold stated that “we have to figure out how we are going to address employee protection as well as the protection of the sterile field.”
Discussions of respiratory protection for health care workers should encompass the education and training of those workers. Frank Califano, North Shore–Long Island Jewish Health System, noted that the use of respirators by health care workers is complicated because the workers may not use respirators as part of their daily routine and therefore respirator use is “out of the norm,” suggesting that “maintaining the equipment, maintaining the training level, [and maintaining the] proficiency level [will] be the hard part.” Califano contrasted the health care workers’ experience to that of firefighters, who are more familiar with, and often rely on, SCBA (self-contained breathing apparatus) devices. These issues were discussed in greater detail later in the workshop.