Meeting An Urgent Need
A New Respirator Performance Standard for Canada
BY SIMON SMITH
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Editor’s note: The author is a volunteer committee member with CSA Group (Canadian Standards Association) but does not represent the organization in any capacity.
Compared with many countries, Canada has a complex regulatory structure for occupational health and safety. Rather than a single national agency such as U.S. OSHA, the thirteen Canadian provincial and territorial bodies have different legislation and regulations, as does the federal government for its own workers. For respiratory protection, while the high-level requirements generally match those of OSHA, detailed guidance on implementation of respiratory protection programs is addressed in a national consensus standard.
Canadian standard CAN/CSA-Z94.4-18, Selection, Use and Care of Respirators, is issued and maintained by CSA Group, a not-for-profit standards development organization, one of several in Canada. The standard was first published in 1982 with the latest update in 2018 and covers topics such as establishing and maintaining respiratory protection programs, respirator selection, and fit testing. It is applicable in all workplaces and is either a legal requirement or cited as a best practice.
With limited exceptions, both CAN/CSA-Z94.4-18 and regional regulations require use of NIOSH-approved respirators where protection is required. A regulatory system combining legislation, the CSA standard, and NIOSH-approved products has been in place and working well for fifty years. Canada had never had a national standard defining respirator performance, but this changed during the COVID-19 pandemic.
BEFORE COVID: SARS
Canada had direct experience with a nascent pandemic with the occurrence in two locations of Severe Acute Respiratory Syndrome (SARS-1) in 2003. In Vancouver, quick application of isolation and use of effective PPE limited transmission to only one healthcare worker, while unfortunately in Toronto, multiple healthcare worker infections and three hospital staff deaths occurred. In the report of the commission of enquiry that followed, several actions and practices were identified to improve preparedness for the next pandemic, all following occupational health and safety principles. The next edition of CAN/CSA Z94.4, published in 2011, was augmented with control banding-based guidance for respirator selection for biological aerosols built on consolidation of existing guidance. CAN/CSA Z94.4 was the first respiratory protection standard in the world to introduce control banding.
THE COVID-19 PANDEMIC: STARTING OUT
One conclusion of the SARS Commission report was to build and maintain respirator stockpiles. While stockpiles were started in some jurisdictions, they were inconsistently replenished when products’ shelf-life expired, and by the start of the COVID-19 pandemic, stocks were very low. Canada consequently faced a similar shortage of respiratory protective equipment as many other countries. While there was one indigenous manufacturer of respirator filters, these were not filtering facepieces, the type in greatest demand.
In response to this crisis, several new filtering facepiece production operations were initiated in Canada—some by existing manufacturers of other PPE and some by start-up companies—and some government funding was provided. All new respirators for Canadian workplaces needed NIOSH approval.
The NIOSH National Personal Protective Technologies Laboratory, which supports the agency’s conformity assessment program, undertook a massive effort to accelerate approvals work with a focus on filtering facepieces but also established a multi-level prioritization structure at the start of the pandemic. Because of its duty to support its national needs, the agency prioritized U.S.-based manufacturers, and approvals of products from Canadian manufacturers took months. Without action, Canada faced not only a limited supply of respirators but also a long wait for new supply sources.
HEALTH CANADA INTERIM ORDER
Health Canada, a department of the Canadian federal government, responded promptly to address the problem.
Historically, Health Canada had never addressed respirators, but one of its regular roles is to approve medical devices. Surgical masks and other basic hospital personal protective equipment are considered “Class 1” devices, the designation for devices that present the lowest potential risk, but at the start of the COVID-19 pandemic the approval system for Class 1 did not cover performance, only aspects of business operation such as recordkeeping and recalls.
In August 2020, Health Canada published an interim order setting requirements for filtering facepieces and elastomeric half-mask particle filtering respirators specifically for use in healthcare. Companies could submit products to Health Canada, which organized testing and issued an approval. Health Canada worked with Canada’s National Research Council (NRC), which operates a laboratory network, to add a facility to support test equipment development.
The requirements in the interim order were drawn primarily from the U.S. Code of Federal Regulations—42 CFR 84, familiarly known as the NIOSH respirator standard—but only those for non-oil-based particle filtering non-powered respirators. Requirements were added for strap strength, biocompatibility, and shelf-life and labelling. Manufacturing quality and documentation requirements were established.
Flammability and fluid resistance criteria from ASTM F2100, Standard Specification for Performance of Materials Used in Medical Face Masks, and ASTM F1862, Standard Test Method for Resistance of Medical Face Masks to Penetration by Synthetic Blood (Horizontal Projection of Fixed Volume at a Known Velocity), were incorporated as options beyond basic performance for healthcare worker use. The resulting matrix of 12 respirator classes matched the N95, N99, and N100 efficiency requirements from 42 CFR 84 with fluid resistance and flammability untested or in combination with ASTM levels 1, 2, or 3. Respirator designations indicated the particle filtration efficiency and, if applicable, ASTM fluid resistance level—for example, “95PFE” or “95PFE-L3”—and products were approved through submission to Health Canada.
The interim order was modified slightly in February 2021 with some clarification of text but no change in requirements. Health Canada indicated throughout that its interim order was intended to meet an urgent need. The task of creating a permanent standard was assigned to CSA Group’s standards development organization, which supported a certification program that replaced the Health Canada interim order after December 2022.
Canada had never had a national standard defining respirator performance, but this changed during the COVID-19 pandemic.
THE NEW CSA STANDARD
As soon as the Health Canada interim order was issued, CSA Group began to consider developing a new performance standard. Its consensus-based process is undertaken by committees of expert volunteers from the stakeholder community and has a robust structure to ensure balanced representation from all interests. To minimize start-up time, members of the existing CSA Z94.4 committee covering selection, use, and care of respirators were organized to form a task group to focus on development of a performance standard for respirators. Additional experts from new manufacturers, test laboratories, government (including Health Canada and NRC), and the medical user community were added to form an expert committee. Speed was critical, so the typical development process was accelerated substantially with all committee work being undertaken online.
A first draft of the standard was created in mid-December 2020. It included performance requirements for filtering respirators for particulate matter, industrial gas/vapor, radiological/nuclear, and CBRN (chemical, biological, radiological, or nuclear) capabilities. However, for the subsequent committee work and document development, it was decided to address only particle filtering respirators in the first edition as this was the immediate priority for healthcare applications. Both negative-pressure and powered-air platforms would be covered. Development of a full standard covering all types of air-purifying and atmosphere-supplying respirators would be a future project, with filtering respirators to be covered in the new standard: CAN/CSA Z94.4.1, Performance of Filtering Respirators. Atmosphere-supplying respirators would be covered in a future CAN/CSA Z94.4.2 standard.
Work proceeded on CAN/CSA Z94.4.1 over the next three months. Three sub-groups focused on specific functions: healthcare requirements, fit testing, and document editing. Input was provided in meetings and through a docket process. In late March 2021 a draft for public review was circulated for a period of 60 days, after which the standard was finalized and approved by the full committee. The final standard was published in October 2021, just under a year after work began. This expedited timeframe reflected the urgency of the need during the pandemic.
Requirements for testing and approval to the new CAN/CSA Z94.4.1-21 standard include manufacturer quality program assessment and audits in addition to the performance requirements set out in the standard. Products approved to this standard are accepted in parallel with the historically recognized 42 CFR 84 in all jurisdictions in Canada so that existing approved products are not affected. The standard’s purpose is simply to speed availability of new products for the Canadian market. It is emphasized that product approval to this standard does not confer NIOSH approval.
CONCEPTS IN DEVELOPMENT
The NIOSH approval structure has been used in Canada since health and safety legislation was formalized. Respirator users and the respiratory protection manufacturer, supply, guidance, and training community therefore have half a century of familiarity with this structure. In the pandemic crisis, it was important to ensure that the new standard was recognized and accepted by these communities. Substantial changes in the classification of respirators covered or performance requirements would be problematic. A standard that appeared to lower protection requirements would not be trusted by the user community, while one that added too many additional base performance requirements could face rejection by manufacturers.
These factors were considered in drafting the standard along with the opportunity to introduce lessons from work on ISO respirator standards. One such aspect was minimization of design restrictions, following the principle of basing requirements only on human performance factors and protection levels needed, so that manufacturers could apply maximum innovation in product development.
PERFORMANCE NEEDS
The development task group included medical professionals who were regular users of respiratory protection during the pandemic and who could share knowledge about respirator use in healthcare facilities under pandemic conditions. Factors raised included breathability, comfort, facility for communication while wearing, cleaning and decontamination, shelf life, extended use, and practical performance evaluation. The standard addressed some of these; for others, inclusion was deferred to later updates. On communication, for instance, there was extensive discussion of criteria and test methods, but more time for analysis was needed. Cleaning was also reviewed intensively, but it was concluded that cleaning needs are so design- and contaminant-specific that only a very general requirement could be set. Extended use and re-use criteria for single-use respirators were also not included as these are very dependent on the design and manufacturer recommendations and were therefore left to manufacturer guidance.
CONTENT OF THE STANDARD
The importance of acceptance and recognition drove retention of the respirator classifications and associated performance requirements in 42 CFR 84. For example, the familiarity of the term “N95” meant that not offering a recognizably equivalent class in Canada could affect adoption of the standard. Therefore, all the particle filtering options in 42 CFR 84 are represented in CAN/CSA Z94.4.1-21. The standard also incorporates the long-standing powered air-purifying respirator “HE” level and the PAPR100-N and -P requirements introduced by NIOSH in April 2020.
Terminology diverges slightly from 42 CFR 84. In the Canadian standard, “type” is used for one design and mode of operation of the respirator, while “class” is used for the combination of type with a specific performance level. “Series” as used in 42 CFR 84 is absent. “CA” is appended to classes; for example, “CA-N95” matches “N95” as used in 42 CFR 84.
The Health Canada interim order had incorporated sets of fluid resistance criteria corresponding to ASTM F2100 Levels 1 to 3 as an optional tested capability on top of base N95, N99, and N100 equivalents. The NIOSH/FDA (U.S. Food and Drug Administration) practice for such “surgical respirators” is to offer an unspecified fluid protection level on class N95 only. A middle ground was chosen for the CSA standard to offer the capability but to keep selection guidance simple. ASTM F2100 Level 3 fluid protection and flammability criteria may be offered on the three N-type filtering facepieces, creating classes designated “CA-N95F,” “CA-N99F,” and “CA-N100F.” The “F” represents fluid/flammability protection.
The standard differs from 42 CFR 84 in the following respects:
Fit testing for filtering facepieces. For all respirator models that seal to the face, quantitative fit testing is required using sodium chloride aerosol in a chamber and human subjects matching the NIOSH bivariate panel with standard movement exercises. Filtering facepieces that NIOSH does not currently fit test are included. Two to five test subjects per panel cell are required, with a total of 25 and a minimum of 30 percent of one sex represented. Minimum fit factors of 100 are required for filtering facepieces and quarter/half-masks. The minimum fit factor for full-face respirators is 500.
A consequence reflecting the minimization of restrictions on design basic to the standard is that ear-loop-type respirators can be approved if they meet fit requirements.
Securing mechanism strength. While 42 CFR 84 has a qualitative requirement for the strength of facepiece straps, the CSA standard includes quantitative force tests on securing mechanisms, adopting criteria from European standards. A minimum 10 newton (N) force test applies to filtering facepiece respirators as in the Health Canada interim order.
Breathability designation. Designations of class CA-N95/N95F respirators are appended to indicate which of three bands of inhalation airflow resistance the product matches based on the maximum of the set submitted. This designation indicates if the airflow resistance maximum at 85 L/min is less than or equal to 100 Pascals (Pa, 10.2 mm water gauge, WG), 175 Pa (17.8 mm WG), or 343 Pa inhalation/245 Pa exhalation (35 and 25 mm WG). These levels are at or below 42 CFR 84 maximum inhalation resistances. This designation (for instance, “CA-N95-175Pa”) assists purchasers in selecting more breathable products if desired and gives targets for manufacturers. The 100 Pa target corresponds with an outcome of Project BREATHE, a program that investigated respirator needs for healthcare workers, which was conducted in the U.S. in the late 2000s.
Shelf life. 42 CFR 84 sets no shelf-life requirement for non-CBRN respirators, but it is common practice for manufacturers to provide a shelf life for filters and certain other components. The CSA standard specifies that the manufacturer must, at a minimum, state a shelf life for filtering components and provide details of the method used to determine it. The standard does not set a requirement for lifetime itself or specify how it is to be established.
Cleaning and decontamination. As noted, this was a point of considerable interest to the user community, but it was found best to leave details to the manufacturer and specify only that a cleaning method must be stated.
Biocompatibility. While 42 CFR 84 states a general requirement to be nonirritating to the skin, the CSA standard references ISO standards for biocompatibility testing for skin-contacting components for all respirator types.
Assessment of reliability. A documented assessment of reliability, which is often undertaken in a Failure Modes Effects Analysis, is required.
Other differences. Minor differences are the addition of nonpreconditioned samples for particle efficiency testing, since research in Canada indicated this could be the worst-case scenario; an additional hydration device flow check consistent with ISO standards; a requirement for a maximum airflow resistance differential for filters used in parallel, matching European requirements; and inclusion of a flow-checking device for powered air systems. Rules on uncertainty of measurement are added, matching ISO requirements, and eye protection performance must be consistent with CAN/CSA Z94.3-20, Eye and Face Protection.
FOR THE FUTURE
The urgency of publication meant that certain points considered for inclusion could not be completed by the original technical committee and will be reviewed when the standard is updated. Communication—both speech clarity and recognition—are important for users. Practical performance testing involves various exercises undertaken by test subjects wearing the respirator and representing the activities and movements of workers. The intent is to assess any impedance in capability such as restriction of motion or dislodging by routine tasks; manufacturers could use the results as an optional but standardized performance claim. A bioburden (cleanliness) test requirement for surgical respirators may be of interest to healthcare users.
CAN/CSA Z94.4.1:21, Performance of Filtering Respirators, is available for purchase online; free access is available for users in Canada. CAN/CSA Z94.4-18, Selection, Use and Care of Respirators, is also available and is now being updated to incorporate the new performance standard and for other needs highlighted during the pandemic. A new edition is expected in 2024.
SIMON SMITH, PhD ARCS CChem, FRSC(UK), is retired from a career in respirator filter design with 3M Canada. He contributes voluntarily in working group leadership roles for the International Organization for Standardization (ISO) and the Canadian Standards Association (CSA Group). He has served as president of the International Society for Respiratory Protection and chair of the AIHA Respiratory Protection Committee.
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RESOURCES
CSA Group: CAN/CSA Z94.4-18, Selection, Use and Care of Respirators (2018).
CSA Group: CAN/CSA Z94.4.1:21, Performance of Filtering Respirators (2021).
Government of Canada: “Guidance on Safety and Performance Specifications for Filtering Facepiece Respirators (FFRs) during COVID-19: Background” (February 2021).
Government of Ontario: The SARS Commission (December 2006).
NIOSH: Title 42, Chapter I, Subchapter G, Part 84, Approval of Respiratory Protective Devices.