A tight-fitting respirator only protects the wearer if it seals to their face. Faces differ, masks differ, and a mask that seals on one person leaks on another. Face fit testing is the check that a specific make, model and size of mask fits a specific person, and it is required wherever tight-fitting respiratory protective equipment is relied on to control exposure.
Where the legal requirement comes from
Not from a regulation that names fit testing. It comes from the duty to ensure that respiratory protective equipment provided is suitable and effective, which appears in COSHH regulation 7, and in the equivalent duties in the asbestos, lead and confined space regimes. An unfitted mask cannot be shown to be effective, so relying on one leaves the control measure unproven.
Qualitative and quantitative
Qualitative testing uses a bitter or sweet test agent and relies on whether the wearer can taste it, and it is suitable only for disposable and half masks. Quantitative testing measures particle concentration inside and outside the mask and produces a numerical fit factor, and it is required for full face masks and is better practice for everything. Both follow HSE's INDG479 and the accompanying protocols.
What invalidates a fit
Facial hair in the seal region is the big one, and there is no workaround: stubble breaks the seal and no amount of tightening fixes it. So do significant weight change, dental work that alters facial contours, and scarring. A change of mask model or size means a new test, because the fit was to that mask and not to masks in general.
What the record should show
The wearer, the date, the make, model and size of mask tested, the test method and equipment, the result including the fit factor where quantitative, and the name and competence of the tester. A certificate that names only the person and not the exact mask is not evidence of anything, because it does not say what fitted.
How often it needs repeating
There is no statutory interval. Retest when anything about the wearer or the mask changes, and review periodically as part of the RPE programme. Many employers work to a repeat test every two years as a discipline, which is a convention rather than a legal requirement.
What substances does COSHH include, and which of them bring you here
Chemicals and much more than chemicals: substances used directly, mixtures, substances produced by a process such as wood dust, welding fume, flour or silica from cutting, fumes and vapours, gases, biological agents, and any material carrying a hazard classification. Lead, asbestos and radiation are outside it because each has its own regulations. The reason that list matters on this page is the control hierarchy: respiratory protection is the LAST control, so a face fit test is evidence that you reached the end of the hierarchy for a substance COSHH covers, and it is worth nothing if extraction or substitution was available and skipped.
Questions people ask about face fit testing
Is face fit testing a legal requirement?
In effect yes, wherever tight-fitting RPE is relied on. The duty is to ensure the equipment is suitable and effective, and fit testing is the recognised way to demonstrate that.
Does a beard stop you passing a face fit test?
Facial hair crossing the sealing surface prevents a reliable seal on a tight-fitting mask. The answer is either being clean shaven in the seal area or using loose-fitting powered RPE, which does not depend on a face seal.
What does a face fit testing certificate prove?
That a named person achieved an adequate fit with a specific make, model and size of mask on a given date using a stated method. It does not transfer to a different mask.
Who can carry out fit testing?
A competent person. HSE operates a voluntary accreditation scheme for fit test providers, and using an accredited tester is the simplest way to evidence competence.
Is a face fit test near me search the right way to book one?
It finds the right kind of provider and tells you nothing about the method, which is what matters. Ask whether the test is qualitative or quantitative, since a qualitative taste test is acceptable for some disposable masks and a quantitative machine test is needed for higher protection factors and is better evidence in any case. Ask that the person tests the actual make, model and size the wearer will use, because a fit test is for one mask rather than for a face. And ask for the record, with the date, the mask, the method and the result, since that is what the assessment relies on.