N95 respirator
An N95 respirator is a disposable filtering facepiece respirator or reusable elastomeric respirator filter that meets the U.S. National Institute for Occupational Safety and Health N95 standard of air filtration, filtering at least 95% of airborne particles that have a mass median aerodynamic diameter of 0.3 micrometers under 42 CFR 84, effective July 1995.
A surgical N95 is also rated against fluids, and is regulated by the US Food and Drug Administration under 21 CFR 878.4040, in addition to NIOSH 42 CFR 84. 42 CFR 84, the federal standard which the N95 is part of, was created to address shortcomings in the prior United States Bureau of Mines respirator testing standards, as well as tuberculosis outbreaks, caused by the HIV/AIDS epidemic in the United States. Since then, N95 respirator has continued to be used as a source control measure in various pandemics that have been experienced in the United States and Canada, including the 2009 swine flu and the COVID-19 pandemic, and has been recommended by the EPA for protection against wildfire smoke.
The N95 respirator is commonly made of a fine mesh of synthetic polymer fibers, specifically a nonwoven polypropylene fabric. It is produced by melt blowing and forms the inner filtration layer that filters out hazardous particles. The N95 standard does not preclude alternative means of filtration, so long as the respirator meets N95 standards and is approved by NIOSH.
"N95" is a trademark of the United States Department of Health and Human Services. It is illegal in the United States to use the term "N95" without the approval of NIOSH.
Regulation
The N95 standard does not require that the respirator be resistant to oil; two other standards, R95 and P95, add that requirement. The N95 type is the most common filtering facepiece respirator. Current filters are an example of a mechanical filter respirator, which provides protection against particulates but not against gases or vapors.An authentic N95 respirator is marked with the text "NIOSH" or the NIOSH logo, the filter class, and, for most filtering facepiece respirators, a "TC" approval number of the form 84A-####, the approval number. All N95 respirators, regardless of type, must be listed on the NIOSH Certified Equipment List or the NIOSH Trusted-Source page, and it must have headbands instead of ear loops.
N95 respirators are considered similar to other respirators regulated under non-U.S. jurisdictions, but slightly different criteria are used to certify their performance, such as the filter efficiency, test agent and flow rate, and permissible pressure drop. For example, FFP2 respirators of the European Union are required to meet at least 94% filtration, and KN95 respirators of China are expected to meet at least 95% filtration. NIOSH found that some products labeled "KN95" failed to meet these standards, some of them filtering out as little as one percent. Both the U.S. Food and Drug Administration and Health Canada require such KN95 products failing to meet the filtration standards to be re-labeled as "face masks" instead of "respirators", when being sold in the U.S. and Canada.
Canadian labor law normally requires NIOSH-approved respirators, like the N95. In 2021, to reduce respirator shortages in Canada, the CSA Group released standard CSA Z94.4.1, allowing for the manufacture of CA-N95 respirators, which are not approved or cleared for use in the United States.
History
Early US respirator standards
Prior to the 1970s, respirator standards were under the purview of the US Bureau of Mines. An example of an early respirator standard, Type A, established in 1926, was intended to protect against mechanically generated dusts produced in mines. These standards were intended to obviate miner deaths, noted to have reached 3,243 by 1907. Prior to the Hawks Nest Tunnel disaster, these standards were merely advisory, as the USBM had no enforcement power at the time. After the disaster, an explicit approval program was established in 1934, along with the introduction of combination Type A/B/C respirator ratings, corresponding to Dusts/Fumes/Mists respectively, with Type D blocking all three, under 30 CFR 14 Schedule 21.The Federal Coal Mine Health and Safety Act establishing MESA, the Occupational Safety and Health Act of 1970, establishing NIOSH, as well as other regulations established around the time, reshuffled regulatory authority for respirators, and moved regulations from Part 14 to Part 11 by 1972, but nonetheless continued the use of USBM-era regulations.
42 CFR 84
Historically, respirators in the US had generally been approved by MESA/MSHA/NIOSH under federal regulation 30 CFR 11. Plans for overhauling Part 11 regulations had been discussed since the late 1980s, with the first proposed rule being published in the Federal Register in August 1987. From the start, respirator regulations were planned to be moved from Title 30 to Title 42, Part 84 in the Code of Federal Regulations, along with the elimination of joint-approval between NIOSH and MSHA. Respirator assigned protection factors were also to be updated, along with chemical cartridge requirements.TB outbreak during the HIV epidemic
In 1992, the multidrug-resistant tuberculosis task force within the CDC was tasked with reducing the incidences of hospital acquired TB infections. TB infections had traditionally occurred mainly in underserved groups and areas, as well as the very young and elderly, and usually had around a 10% chance of turning into an active TB infection in a given person's lifetime.HIV/AIDS, was noted to be one of the strongest factors for TB activation, since most TB outbreaks and mortalities reported at the time involved healthcare workers and patients infected with HIV. Respiratory protection and the performance of respirators were emphasized in the 1994 guidelines to controlling TB, which, at the time, were limited to respirators equipped with HEPA filters.
To quickly address the HEPA-only respirator requirement for TB controls, stemming from the lack of biological protection in the existing 30 CFR 11 standards, NIOSH aimed to have the proposed 42 CFR rule changes finished by the end of 1994. The proposal at the time would drop the HEPA classification for non-powered respirators, and add three respirator types, at the time called Type A, B and C, with filtration efficiencies of greater than or equal to 99.97%, 99%, and 95% respectively, with Type C corresponding to the current N95 standard.
According to NIOSH, all the new respirator types proposed in 42 CFR 84, including Type C, would meet the CDC's requirement for protection against TB, and would provide avenues for cheaper NIOSH-approved respirators without the need for HEPA or NIOSH class-100 filters.
After the passage of 42 CFR 84, a 1999 NIOSH guide for health care administrators noted that respirators selected for TB prevention under 42 CFR would likely be N95 respirators.
Approval of Part 84 and replacement of 30 CFR 11
In July 1995, in response to respirators exhibiting "low initial efficiency levels", new 42 CFR 84 standards, including the N95 standard, were enforced under a three-year transition period, ending in July 1998. The standard for N95 respirators includes, but is not limited to, a filtration of at least 95% under a 0.3 micrometer 200 milligram test load of sodium chloride. Standards and specifications are also subject to change.Once 42 CFR 84 was in effect, MSHA, under a proposed rule change to 30 CFR 11, 70, and 71, would withdraw from the approval process of rated respirators.
Use
Voluntary respirator use
When in an environment where no designated hazards are present, OSHA mandated respirator requirements are limited to Appendix D of 1910.134. Voluntary respirator users under Appendix D are only obligated to follow manufacturer instructions for maintenance, use, and warnings, and to keep track of the respirator. OSHA encourages the use of respirators, even if only voluntarily.OSHA advises voluntary respirator users receive a copy of 1910.134 Appendix D, as well as verify that the respirator used, be it powered-air purifying, self-contained, or facepiece-filtering, is not a potential health hazard.
During wildfires
The EPA recommends wearing a N95 or P100 respirator during a wildfire for protection against smoke. Masks to avoid are those with a single strap or a mask with earloops.In addition to recommending NIOSH-approved respirators, the EPA also recommends building air purifiers to improve indoor air quality when commercial air purifiers are unavailable or unaffordable.
NIOSH is in the process of developing a hazard review on smoke exposure among outdoor workers. The current draft, as of 2024 advises the use of N95 respirators, as well as engineering and administrative controls.
When mandated by employers
is a critical component to a respiratory protection program whenever workers use tight-fitting respirators in a hazardous environment. OSHA requires an initial respirator fit test to identify the right model, style, and size respirator for each worker; as well, as annual fit tests. Additionally, tight-fitting respirators, including the N95, require a user seal check each time one is put on. Facial hair at the sealing area of the respirator will cause it to leak.When use of a respirator is mandated by an employer, OSHA regulations require a medical evaluation. In the United States medical evaluation is required once, prior to initial fit testing and use, although it may need to be repeated if any adverse signs or symptoms are observed. Correct use of the respirator decreases the chances of airborne contamination by viruses.
For persons who are medically disqualified from negative-pressure respirators, or who cannot pass a fit test due to facial hair or other reasons, a powered air-purifying respirator is a possible alternative.
The rules on wearing respirators are similar in Canada. SOR 86-304 dictates that, when employees are expected to do work in a hazardous environment, they must wear respirators approved by NIOSH, and must follow the procedures in CSA Z94.4 when fitting respirators.