Respiratory protection: Face fitting
Although personal protective equipment (PPE) should only be used as a last resort, respiratory protective equipment (RPE) still has an important role in protecting employees from inhaling hazardous substances.
The RPE is generally of two types:
- Respirators that rely on filtering harmful substances
- Breathing apparatus (BA), which gives an independent supply of breathable air, for example fresh-air hose, compressed airline and self-contained BA.
Both types are available with a range of face-pieces: masks, hoods, helmets, visors and blouses. Masks are tight fitting face-pieces which cannot protect the wearer if they leak. A major cause of leaks is poor fit and, consequently, essential that a mask is tight-fitting.
The person
Tight-fitting face mask RPE relies on a good seal to the face and, therefore, must be of the right size and correctly fit the wearer. If it does not fit correctly the protection is wasted. Faces come in all shapes and sizes, as do face-pieces, and for each individual wearer a suitable face-piece must be selected, which is capable of fitting their face and sealing adequately to their face.
Facial hair — both stubble and beards —– can break the seal on tight-fitting face-pieces allowing the user to breathe in hazardous substances. Workers who are not clean-shaven cannot use face mask RPE and so must be clean-shaven at the start of their shift. If possible, facilities for shaving before the shift should be provided. Workers who have beards, or are unable to be clean-shaven, should be provided with appropriate loose-fitting RPE rather than RPE that relies on a tight-fit.
The compatibility of other personal protective equipment, particularly safety glasses, can break the seal on tight-fitting face-pieces. Steps have to be taken to ensure the other personal protective equipment does not interfere with the seal. One way this can be achieved is by the use of combination products, for example, face masks that incorporate goggles.
The requirement for a fit-test
Face-piece fit testing is a method of checking that a tight-fitting face-piece matches the wearer’s facial features and seals adequately to their face. The Approved Codes of Practice (ACOPs) for the Control of Substances Hazardous to Health Regulations 2002 (COSHH), the Control of Lead at Work Regulations 2002, the Control of Asbestos Regulations 2012, and the Confined Spaces Regulations 1997, all require that tight-fitting face-piece RPE should be fit tested.
The fit test
A fit test measures of how effectively a tight-fitting face-piece seals to an individual wearer’s face. It should be included in the initial selection of the mask, to ensure the mask fits the wearer and provides a good seal to their face. It is good practice to have a system to ensure repeat fit testing is carried out on a regular basis, especially when RPE is used frequently as a key element of exposure control, e.g. workers involved in licensed asbestos removal.
Fit testing should be repeated when changing to a different model of RPE or to a different sized face-piece. It should be repeated — if there have been significant changes — to the facial characteristics of the individual wearer, such as the consequence of significant weight change, scars or changes caused by dentistry. The fit test should not be performed on personnel who have facial hair in the area of the seal.
It should be noted that the fit test just assesses the effectiveness of the mask’s seal to the face and is not indicative of the amount of protection it provides the wearer with in the workplace. Other factors, such as the characteristics of the filter and the way the RPE is used by the worker, must be considered.
Fit tests require the wearer to perform various exercises during the test. These exercises generate a physical workload on the wearer that simulates working activities and work rate. This tests the fit of the face-piece better than if the wearer is at rest.
The fit test: The competent person
The RPE fit testing should be conducted by a competent person, e.g. a person who is appropriately trained, qualified and experienced, and is provided with appropriate information to undertake each particular task. The British Safety Industry Federation has introduced the Fit2Fit RPE Fit Test Providers Accreditation Scheme, ensuring that the fit tester is appropriately accredited by the Fit2Fit scheme, is one way for employers to provide proof that the tester was competent in the event of an incident.
The test: qualitative
The fit test can be qualitative or quantitative. The qualitative test can be used for tight fitting respirators, with the exception of full face masks. It is a pass/fail test method that does not measure the actual amount of leakage.
The test uses a hood to create a small test chamber around the user’s head, a test solution, and makes use of the wearer’s sense of taste or smell, or reaction to an irritant, in order to detect leakage into the respirator face-piece. Most tests are based on detecting the taste of Bitrex or saccharin.
The first step in the qualitative fit test is the sensitivity test, which checks whether the wearer can taste the sensitivity test solution. This is carried out before the face mask seal is tested. A few drops of the sensitivity test solution are placed into the sensitivity nebuliser, and then the test hood is put on the person, before they wear the face mask. The person is instructed to indicate as soon as they taste the solution. Anyone who cannot detect the test solution will need to use a different fit test method, either using an alternative solution or a quantitative test. The test itself cannot be carried out until the person being tested can no longer detect the sensitivity test solution.
After a successful fit test, the wearer should reach up into the hood and break the seal between the mask and the face with their finger. They should then be able to taste the test solution. If not, the test should be repeated.
The test: quantitative
Quantitative fit testing can be used on all tight-fitting respirators including full face masks. The test is based on a portable particle counting device, which compares the particles outside a wearer’s mask, with those inside the mask that have got past the face seal. This quantitative result contrasts to the yes/no result given by the qualitative test.
Qualitative v quantitative
The qualitative fit test makes use of the wearer’s ability to detect the taste of a test solution, and due to this, holds an advantage over the quantitative test methodology, since it stops the challenge particles from passing through the filtering material in a form which can be detected. However, being a subjective method, the qualitative fit test is dependent on the wearer’s taste response and therefore is open to abuse. Some organisations have decided to accept only quantitative test certificates, as evidence of successful face-fit test.
Alternatively, RR1029: Review of fit test pass criteria for Filtering Facepieces Class 3 (FFP3) Respirators, a report by the Health and Safety Executive’s Health and Safety Laboratory, concluded that, “The Bitrex qualitative fit test method has been shown to give a good determination of fit in this study”.
User check
A fit test should not be confused with a user fit-check, which is a quick check performed by the wearer when the respirator is put on. A fit test involves placing a hand over the filter or inlet valve(s), and breathing in. If there is a good seal, the wearer will experience the mask sucking in toward their face. On holding breath (for 10 seconds), the face-piece should not loosen. If it does, the face-piece should be readjusted and the seal checked again.
In RR1029, it was demonstrated that the fit-check was of very little value as a substitute for a fit test.
Failure to meet the current HSE pass criterion
The RR1029 report compared results from fit tests on nine face-piece Class 3 (FFP3) respirators, using four fit test methods. Some FFP3s used in this study, were found to readily fit a significant proportion of the test subjects, with a range of face sizes, across all four fit test methods. Other FFP3s were poor at fitting all of the test subjects. It was concluded that there is room for significant improvement in the design of some FFP3s towards better wearer fit, which could be aided by more stringent standard requirements for FFP3.
The report illustrated the importance of fit testing, before relying upon a FFP3 for respiratory protection. It concluded poor attention to design detail of some FFP3s, with insufficient focus on the importance of good wearer fit, is a significant factor leading to poor fit.
Training
An appropriate training programme for workers who use tight-fitting face mask RPE should include how to wear and check the RPE correctly and why fit testing is required. The fit test itself can be used as a training opportunity, as it provides an opportunity to highlight to the wearer, the consequences of poor fit and improper use on the effectiveness of the RPE device.
The importance of fit testing
As faces come in an infinite variety of shapes and sizes, there is no chance of one particular type or size of tight-fitting face-piece will fit all persons. That being so, it is important that fit testing is carried out to ensure that the face-piece selected provides a good seal.