Demystifying fit check vs fit test

Despite the constant conversation around the importance of face fit testing for RPE during the selection and validation process, we are still seeing evidence that health and safety professionals are confusing this with fit checking. When it comes to 3M respiratory protection, we have incorporated various methods of fit checking into our products depending on their design. But what is fit checking and how does it differ from fit testing? 

 

The Health and Safety Executive (HSE) outlines both procedures within its guidance document ‘Fit testing of respiratory protective equipment facepieces’. It is important that people working with respiratory equipment fully understand the two types of examination. 

 

Fit testing is a requirement across all industries where RPE with tight-fitting facepieces, such as disposable respirators and half and full face reusable respirators, are used as a control measure. The HSE describes it as “a method for checking that a tight-fitting facepiece matches the person’s facial features and seals adequately to the wearer’s face. It will also help to identify unsuitable facepices which should not be used.” This robust process is to ensure that a worker is equipped initially with RPE that can achieve an adequate fit to their face whereas fit checking is a quick judgement on the quality of fit at each time of use.

There are a number of recommended ways to implement fit testing. Whichever method is used it must be carried out by a competent person.  The competencies expected are laid out in the HSE’s fit testing guidance and there are various ways of demonstrating competency. One way is through the British Safety Industry Federation’s (BSIF) ‘Fit2Fit RPE Fit Test Provider Accreditation Scheme’.

 

The two methods of RPE fit testing used routinely are a qualitative taste test and a quantitative particle counting test. Qualitative fit testing is a simple pass/fail test based on the wearer’s subjective assessment of the inward leakage of a test agent via the face seal region. The test kits are relatively inexpensive and are typically used by employers performing ‘in-house’ testing. Quantitative fit testing provides a numerical measure of the fit achieved that is called a ‘fit factor’ giving an objective measure of face fit. This method uses specialised electronic equipment and is often used by fit testers offering a chargeable service to employers.

 

It is important to ensure that the fit of a respirator is checked every time it is put on, to be confident it is properly positioned.  A fit check helps the wearer idenify gross errors in fitting and will detect some possible faults with products each time the respirator is worn. It does not detect the fine leaks that will be identified through fit testing.

 

Fit checking is not a regulatory requirement, but it should be regarded as good practice and built into the routine of wearers, to the degree that it becomes an automatic action each time the respirator is put on – even if that occurs several times a day. A fit check is never a replacement for undertaking face fit testing. Face fit testing should always be carried out for every wearer of tight fitting respirators and on each model of mask they wear. 

 

Fit checking uses various techniques to create either negative or positive pressure inside the facepiece depending on the model of respirator. The wearer then judges the quality of fit by how the pressure is maintained or alters. To test for positive pressure the exhalation valve needs to be closed off and the user should exhale into the facepiece. It will be considered satisfactory if a slight positive pressure can be built up inside the facepiece without any evidence of outward leakage of the air at the seal. In order to test for negative pressure a similar process is carried out by covering the inlet(s) of the facepiece and if it remains in its slightly collapsed condition with no noticeable inward leakage of air then this again is satisfactory.

 

RPE is used in a number of industries including metal processing, food and beverage and construction to name but a few. It is important that employers implement a fit testing programme and train their staff in fit checking and other apsects of RPE use, for example filter life and care and maintenance of products where it is required. 

 

 

3M will be at Health & Safety North on Stand D2.