According to the requirements laid out in the Health & Safety Executives (HSE) guidance note HSE INDG 479 and HSG53 care must be taken to ensure that respirators fit perfectly. By performing fit tests, you can be sure that you meet these requirements.

The seal fit must be rechecked for the following changes in mask or wearer:

• weight changes
• major dental treatments
• facial piercings
• new PPE that may affect the seal fit
• change of mask types, models or materials

The so-called fit factor confirms when a tested mask meets the requirements for the desired sealing at the time of the test. 

Loose-fitting respiratory protection such as hoods for air purifying respirators or escape devices which use a mouthpiece do not require a fit test.

In addition to fit tests, proper training of the wearer plays a fundamental role.

Important factors are:

• the visual inspection of the mask
• correct donning
• the performance of fit checks before each use

• incorrect fit of the mask
• beard growth
• speaking, sneezing, laughing and other facial movements
• an unsuitable shape or size of mask for the test person

A Fit Test uses test substances and/or a device to check the sealing of a mask when performing certain exercises, while a Fit Check ensures that the mask fits properly before each use. A Fit Check does not replace a Fit Test.

The passing or failing of a qualitative fit test depends on whether the test person can taste or smell the test substance or not and thus provides subjective results. A quantitative fit test provides objective results by using a particle counter or controlled negative pressure to measure the sealing of the mask. Both methods are acceptable. So you can choose the method that is most appropriate for the respirator being used and its wearer.