Coming Soon:
New Respirator​ Classifications

Will the ISO Respirator Standards Do Away with Assigned Protection Factors?

By Craig Colton ​​
In October 2002, a subcommittee of the International Organization for Standardization (ISO) met in London to begin developing performance standards for respiratory protective devices (RPD). Now, after 12 years of meetings, the end of this long process appears to be in sight. Forthcoming guidance from ISO could standardize the performance requirements for RPD used by wearers in hazardous environments and make the standards more “wearer centric” than existing standards.
If adopted in the U.S., the ISO guidance will replace the RPD classification and terminology used by NIOSH, and could result in the elimination of OSHA’s assigned protection factors (APF). The changes will impact more than just respirator manufacturers; anyone using respirators will be affected by new selection procedures and different RPD classification. HARMONIZATION Many countries have their own performance standards and methods for assessing RPD conformity. The existence of multiple standards has several implications that can make respirator selection confusing. For example, respirator manufacturers around the world may have similar (though perhaps not identical) products, and identical products may exist that have different performance claims. To attain the same respirator performance in multiple locations, it may be necessary to select multiple products. For example, RPD particle filters may differ between countries. Sometimes the filter efficiency requirements for two products might be the same but measured differently, resulting in slightly different laboratory performance.
This lack of harmonized standards can cause challenges when trying to make a global recommendation for a common hazard. During the 2002–2004 outbreak of Severe Acute Respiratory Syndrome (SARS), health authorities recommended that healthcare workers wear NIOSH-approved filtering-facepiece N95 particulate-
removing respirators. The recommendation of this specific product—perhaps due to the Centers for Disease Control and Prevention’s (CDC) involvement with SARS in Asia—contributed to a product shortage as the disease spread. Other potentially acceptable respirators were available that were similar to the N95, such as the FFP2, a particle-filtering half mask with a filter meeting P2 requirements in the European standard Respiratory protective devices – Filtering half masks to protect against particles – Requirements, testing, marking (EN 149). Only after the World Health Organization became aware of the similarities of the N95 and the FFP2 was the recommendation broadened to include FFP2 where it was available.
Today’s system also creates challenges for multinational companies trying to standardize on the same RPD in their facilities for the same task or hazard. While a respirator sold around the world may be identical in its manufacture, different countries can assign a different level of protection to it. The ISO system could eliminate these disparities by leading to greater harmonization worldwide. WEARER-CENTRIC FOCUS Because the ISO requirements have tried to focus on human factors and the wearer’s tolerance and ability, much of the ISO subcommittee’s initial work consisted of developing technical specifications for the standard writers. Many of the documents address issues where RPD may create burden for the wearer, including anthropometrics, wearer work rates, work of breathing, and effects of atypical levels of carbon dioxide, oxygen, and temperature as a result of wearing an RPD.
To accomplish the task, thirty-two subcommittee outputs have been identified. The first standard (ISO16972:2010) developed addressed the terminology used for the forthcoming RPD. Fourteen outputs have been completed, and the others are nearing completion. The sidebar below shows the list of work items, their completion status, and my estimate of the likely completion date for items in progress. These work items include two performance standards: one for filtering RPD (also known as air-purifying respirators) and one for supplied breathable gas RPD (atmosphere-supplying respirators). In addition, three related documents cover RPD selection, use, maintenance, and fit-testing of respirator wearers. The ISO RPD classification is described in 16973.
One result of this wearer-centric approach is to classify an RPD based on its performance rather than design. Table 1 provides examples of possible ISO RPD classifications; as is evident, the ISO RPD classifications could result in a big change to the way we refer to RPD today around the world.
DIFFERENCES IN CLASSIFICATION Today in the U.S., RPD are classified by type—for example, half-facepiece organic vapor respirator, or 30-minute pressure-demand self-contained breathing apparatus (SCBA). The type determines which NIOSH requirements need to be met and its assigned protection factor from the OSHA respiratory protection standard. (The half-facepiece RPD has an APF of 10, while the required APF for the SCBA is 10,000.) Under the ISO framework, however, classification would likely be based on many factors, including the work rate the RPD is designed for and tested at; the particle filter efficiency or the chemical cartridge type and capacity; respiratory interface (for example, facepiece, hood, helmet, and so on); and the ISO protection class it meets based on a laboratory test. Table 1 shows possible classifications for three hypothetical half-facepiece particulate-removing RPD. Assuming these respirators are NIOSH approved, they would have an APF of 10 when an employer implements a continuing effective respiratory protection program meeting the OSHA respiratory protection standard. Depending on how they are built, all three could have different classifications under ISO. One RPD could be classified PC2 W1 bT F2 RPD. Such a classification indicates that the RPD meets requirements for protection class 2 for workers performing at work rate 1, and has a tight-fitting type-b respiratory interface (in other words, it covers the mouth and nose) with a class 2 particle filter (95 percent efficient in the laboratory test). The third RPD in the table could be another half-facepiece RPD classified as PC4 W1 bT F4 RPD. This device is similar to the first except that it meets protection class 4 with a class F4 particle filter (99.9 percent efficient in the same laboratory test). Under the U.S. system, all three examples would offer the same level of protection; under ISO, three devices that look almost identical could offer three different levels of protection. CHALLENGES Once these standards are completed and have achieved consensus, several challenges will remain, including adoption by countries around the world, determination of the protection levels, and the complexity of the classification scheme. Adoption Many countries have existing national regulations for RPD performance. In the U.S., these regulations are established by NIOSH. Some have existing RPD selection and use standards; in the U.S., these standards are covered in OSHA 29 CFR 1910.134. It seems unlikely that countries with existing standards will be able to adopt the forthcoming ISO standards without change. For instance, the U.S. government’s rulemaking process involves public notice and comment. NIOSH is currently evaluating options on how to adopt or incorporate the ISO performance requirements. How do these standards fit in? OSHA has its own regulation for selection and use that includes the APF of RPD. Will OSHA accept “ISO RPD” in addition to the NIOSH-approved respirators? Having completed the respiratory protection standard in 2006, is OSHA likely to want to change it? As these questions indicate, there is a great deal of uncertainty regarding U.S. adoption of any ISO guidance.
In Europe, the ISO respiratory protection standards will not automatically replace the Committee for European Standardization (CEN) respiratory protection standards. In November 2012, the European standards committee (CEN TC79) proposed a six-year evolution period for ISO standards. If countries do not adopt these ISO standards, this could prevent the broad harmonization of RPD performance requirements. Protection Level Many countries use the APF or another protection factor term to describe the protection level provided by an RPD. In the U.S., OSHA went through extensive rulemaking that included reviewing workplace protection factor studies, and, where they did not exist, simulated workplace protection factor studies to establish its APF.
The protection level for RPD that meet ISO requirements is presently based on a Total Inward Leakage (TIL) test. This test involves a person donning the respirator and performing various exercises in a laboratory test chamber. A test agent is generated and measured inside and outside the RPD. The inside measurement may include filter penetration. ISO proposes to use this test to identify the protection class the RPD meets.
A TIL test has been used in Europe for years to establish the nominal protection factor (NPF) for RPD, and the NPF has been used as the protection level for RPD in Europe. With ISO considering the TIL test as a potential harmonizing measure across RPD in various countries, three different test methods have been proposed to be used interchangeably for measuring TIL, and none of them have been correlated to the workplace. Several issues remain for ISO to address, including the appropriate number of people to test, the test aerosol, the number of RPD donnings, what constitutes an independent data point (for example, a single donning or a single exercise), which movements should be included in the test exercises, and what relevance those exercises should have to the workplace.
Some examples provide context for the challenges that lie ahead. In Europe, for full-facepiece air-purifying respirators with P3 filters, which are similar to the 100-level filters in the U.S., the NPF based on a TIL test is reported as 1000 in EN 529, Respiratory protective devices – Recommendations for selection, use, care and maintenance. However, in workplace protection factor studies, full-facepiece respirators with P3 or high-efficiency filters have not come close to performing at this level, and in the U.S., the OSHA APF for these RPD is 50. It seems as though ISO will want to consider ways in which the protection level of ISO RPD should be evaluated or correlated to the workplace before they are published. Complexity of Classification At a minimum, the new classification will require RPD users and wearers to learn a new system for referring to the respirator. Will employers and workers be able to make the transition from using a half-facepiece N95 respirator to, for instance, a PC3 W1 bT F2 RPD?
TO LEARN MORE In attempts to publicize the ISO standards, the AIHA Respiratory Protection Committee sponsored roundtables at AIHce in 2011 and 2014. Despite these efforts, and even though the ISO activity has spanned the past decade, few industrial hygienists seem aware of it. To learn more about the coming ISO changes, talk with a member of the U.S. Technical Advisory Group (TAG) for ISO TC 94 SC15. To get more information on the U.S. TAG, contact Colleen Miller, USTAG Administrator, at or (412) 386-4956. The U.S. TAG welcome page can be found at AIHce and the International Society for Respiratory Protection (ISRP) hold conferences with roundtables and technical papers on the ISO standards. CRAIG COLTON, CIH, is division scientist for regulatory affairs for 3M in St. Paul, Minn. He can be reached at (651) 733-6297 or