The Standards Behind Masks: EN 149, EN 14683, NIOSH and Others

A mask label such as FFP2, Type IIR or N95 is shorthand for a test that someone ran on a sample. Knowing what the test measured, and what it did not, makes the label far more useful. This sheet covers the European standards EN 149 and EN 14683, the US NIOSH respirator rules in 42 CFR Part 84, and the standards for barrier face coverings and community face coverings, each described only as the opened pages state it. Standards are summarised here, not quoted.

EN 149: filtering half masks and the FFP classes

EN 149 covers filtering half masks, the disposable respirators sold as FFP1, FFP2 and FFP3. A 2021 peer-reviewed review in Annals of Work Exposures and Health lists minimum filtration efficiency of 80, 94 and 99 percent for the three classes, and mean total inward leakage limits of 22, 8 and 2 percent. Total inward leakage means everything that gets in: through the face seal, through any valve and through the filter itself. EN 149 certification includes tests on human subjects for that leakage, and the filtration testing is done by the manufacturer according to the review.

The UK Health and Safety Executive (page dated 7 August 2024) says respirators for work must be CE marked and marked with the standard, EN 149:2001 in its wording, plus the FFP class. It adds that the FFP1, FFP2 and FFP3 classes can reduce the amount of dust breathed by factors of 4, 10 and 20, if the respirator fits well and is used correctly.

EN 14683: medical face masks

EN 14683 covers medical masks, which the US calls surgical masks. According to the 2021 review, its three types are defined by bacterial filtration efficiency (BFE): at least 95 percent for Type I, and at least 98 percent for Types II and IIR. Only Type IIR also requires fluid resistance (at least 16 kPa) for splash protection. The review adds that Type I is meant for patients and the public during epidemics, and Types II and IIR for protecting hospital staff and patients in procedures.

The test is run on a piece of mask material of 4.9 square centimetres at 8 litres per minute, not on a mask on a face. The UK regulator MHRA (page last updated 1 July 2023) says a transparent mask may state Type IIR only when it has met EN 14683:2019 in full.

NIOSH and 42 CFR Part 84

In the United States, NIOSH tests and approves respirators under 42 CFR Part 84. Its page on identifying approved respirators (21 January 2025) says an N95 must not allow more than 5 percent of a near worst-case penetrating aerosol through, and that every approved respirator carries an approval number beginning TC. NIOSH's 2009 bulletin adds that the test uses a salt aerosol of about 0.3 micrometres at 85 litres per minute after humidity conditioning. The 2021 review notes that, unlike EN 149, US fit testing is the employer's responsibility under a separate rule (29 CFR 1910.134) and is not part of certification.

Barrier and community face coverings

For masks made for the public, NIOSH (25 March 2025) says barrier face coverings meet the ASTM F3502-21 standard and are tested by a laboratory, with filtration of at least 20 percent at the base level and 50 or 80 percent at enhanced levels. In Europe, the CEN Workshop Agreement CWA 17553:2020 gave minimum requirements for community face coverings. CEN (22 November 2022) says a workshop agreement is not an official standard, and that it was followed by the technical specification CEN/TS 17553:2022, published on 2 November 2022. CEN states that community face coverings are neither PPE nor medical devices. The 2021 review reports that the workshop agreement used filtration testing with 3.0 micrometre particles.

What a standard does not tell you

• Your fit. The HSE says the only way to know a disposable respirator seals well enough is a proper fit test. A standard tests samples on test subjects, not you.
• Protection of others. NIOSH says there is no standard test of the protection a respirator or mask gives to people around the wearer.
• Quality control. NIOSH says international standards often do not require manufacturers to demonstrate quality in the way NIOSH approval does.
• Comparability. Test aerosol, airflow and what is tested (a mask or a piece of fabric) differ between standards, so a percentage from one is not directly comparable with another.

A marking therefore says a product was designed and tested to a rule, and is not the same as a good fit on your face. For how to check the seal, see fit and seal. For markings that are copied or misused, see counterfeit and misdescribed respirators. For the product groups themselves, see types of masks and respirators. This is general information, and an occupational-health adviser can say what a particular workplace requires.

The short version

EN 149 sets the FFP classes for respirators, EN 14683 sets types for medical masks by bacterial filtration, NIOSH Part 84 approves respirators such as the N95, and ASTM and CEN documents cover coverings for the public. Each tests something different in a different way. None replaces a fit check on your own face.