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If your company uses tight-fitting respiratory protective equipment (RPE) then a fit test is a legal requirement. The fit test functions to ensure the mask correctly fits the wearer’s face. Therefore it is able to provide its stated respiratory protection. Ill-fitting masks will not have the required tight seal and are leaky and vulnerable to bypass by contaminants. Faces come in all shapes and sizes so it's not realistic to expect one mask to fit everyone.
[caption id="attachment_16250" align="aligncenter" width="300"] The FT30 bitter Fit Test Kit by 3M[/caption]
Mask types that require a fit test are:
- Disposable respirators (Qualitative or Quantitative test)
- Re-useable half face masks (Qualitative or Quantitative test)
- Re-useable full face masks (Quantitative test only)
Fit testing and facial hair
The seal on tight fitting RPE will be compromised if you have facial hair and stubble you cannot carry out a fit test. However if you must keep your facial fair, non-tight fitting RPE alternatives are available which do not rely on the tight facial seal.What’s the difference between a fit test and a fit check?
A fit test is the responsibility of employer. It should be completed before any work is carried out in the hazardous environment, therefore ensuring tight fitting RPE fits the wearer correctly. This differs from a fit check which should be carried out every time the respirator is put on and is the responsibility of the wearer. The wearer uses positive and negative pressure techniques to judge the fit of the mask and whilst not required by law it is good working practise to carry out every time before use. Manufacturers provide their own instructions on how to perform the fit check, but generally once you have put the mask on and moulded the nose piece to your nose if necessary, for a valved respirator you cover the front of the mask with the palms of both hands and inhale sharply. The respirator should collapse slightly on to your face. For an unvalved respirator, cover the front with your palms and exhale sharply, the mask should expand slightly and you should not be able to feel leaks at the seals. If the fit check does not pass, you can adjust the nose piece and the position of the mask slightly. However if you re-perform the fit check and you cannot achieve the sufficient fit, you should not wear the mask for work, as its protection will be compromised.How to perform a fit test
A complete fit test is performed in two parts called the sensitivity test and the fit test and will use two types of solutions:- Sensitivity solution for the sensitivity test. You put the test hood on the subject. Then count the number of squeezes of the nebuliser it takes for them to taste the sensitivity solution without their mask on. This informs the tester of how sensitive the subject will be to the test solution.
- Test solution for the fit test. Get the subject to put on their mask and then put the test hood on the. Add the initial dose (based on the sensitivty test) of test solution. This is then topped up with subsequent doses, again based on the results from the sensitivity test. The subject carries out a number of exercises to see if they can taste the test solution. If they fail, the test can be repeated once. If failure is still recorded, stop the test and try an alternative mask.