The best fit

10 May 2021

The use of respiratory protective equipment (RPE) is on the increase, and with many of us using this type of equipment for the first time, Neil O’Regan takes this opportunity to explain the different options and tells you what you need to know about Fit Testing.

FACE MASKS are required in every-day life now like never before and we’re all aware that washable and reusable face coverings help to prevent the spread of the COVID-19 virus when we’re out and about.  

But many of us have also either started to wear, or noticed others wearing, other types of respirators - known as respiratory protective equipment (RPE) - over the last 12 months.  Examples of types of tight-fitting facepieces are shown below:

Disposable Filtering Facepiece (FFP)

Reusable half mask

Reusable full-face mask.

For those new to wearing RPE, there has been a lot of discussion regarding the differences between the respirators and how to wear them correctly. There is also growing momentum to switch from disposable respirators to reusable ones, for economic as well as sustainability reasons.

RPE such as disposable filtering facepieces (FFPs), reusable half-masks and full-face masks have been standard pieces of protective equipment within many working environments for years. However, according to the BSIF, research indicates that a significant amount of the RPE in use does not offer the user the expected level of protection because it does not fit properly.

People come in various shapes and sizes, so there is no ‘one size fits all’ solution. If the RPE leaks it may be down to poor fit, so ensuring it is properly assessed for each individual is a vital and legally required step in the UK. This process is known as Fit Testing.

Who regulates Fit Testing?

The Health and Safety Executive (HSE) is the UK government agency responsible for the encouragement, regulation and enforcement of workplace health, safety and welfare. RPE fit testing is the subject of the HSE’s INDG 479 guidance document and it must be carried out by a competent person.

Working closely with the HSE, the BSIF developed the Fit2Fit Accredited RPE Fit Test provider scheme to improve the health of those wearing tight-fitting RPE by providing a list of accredited and competent providers. The list shows the tester’s geographic location, the area they cover and the method/s of fit testing they have been accredited against. 

Who needs a Fit Test?
A fit test should be carried out on any individual who is required to wear tight-fitting RPE which relies on a good seal between the mask and the wearer’s skin. The test should be carried out at the mask selection stage, before a particular type of respirator, whether a disposable mask, half mask or full mask is used for the first time. A range of suitable mask options should be on offer for the wearer to try.

Respiratory devices that include a loose-fitting hood or constant-flow airline breathing apparatus do not need to be fit tested, but separate appropriate measures should be taken to make sure it is being worn correctly. 

How often should I Fit Test?

Statement from the HSE:
“In preparing the Fit2Fit RPE fit testers accreditation scheme, BSIF and other industry stakeholders have worked closely with the experts in Health and Safety Executive (HSE). Following this scheme is not compulsory and employers are free to take other action to comply with the law. But if you follow this scheme, you will be doing enough to demonstrate good practice.”​
A fit test should be repeated whenever there is a change to the RPE type, size, model or material or whenever there is a change to the circumstances of the wearer that could alter the fit of the RPE for example: weight loss or gain, substantial dental work, any facial changes (scars, moles, effects of ageing etc) around the face seal area, facial piercings, introduction or change in other head-worn personal protective equipment (PPE).

The Health and Safety Executive (HSE) does not stipulate a frequency of testing, however the Fit2Fit RPE Fit Tester Provider Accreditation Scheme recommends that a suitable interval for repeat fit testing is two years. In some situations, more frequent repeat fit testing may be appropriate, particularly where RPE is being used as a primary or sole means of control.

Is Fit Testing a legal requirement?
It is a legal requirement that workers using tight-fitting respiratory protective equipment (facepieces/masks) must be fit tested by a competent person. 

The Health and Safety at Work Act 1974 and the Management of Health and Safety at Work Regulations 1999 require employers to provide and maintain a safe working environment. In addition to the COSHH Regulations 2002, RPE may need to be used to satisfy requirements in the following pieces of legislation:

  • Control of Asbestos Regulations 2012

  • Control of Lead at Work Regulations 2002

  • Ionising Radiations Regulations 1999

  • Confined Spaces Regulations 1997.

These Regulations are supported by Approved Codes of Practice (ACOPs), give practical guidance on compliance and have a special status in law. For RPE use that is not covered by any of the above Regulations, employers and employees have duties to follow under the Personal Protective Equipment at Work Regulations 1992.

Who can perform a Fit Test?
RPE fit testing should be conducted by a competent person who is appropriately trained, qualified and experienced in providing appropriate guidance to respiratory wearers. A list of Fit2Fit-accredited fit testers can be can be found at the Fit2Fit website:

A pre-use wearer seal check should be carried out each time a fit-tested facepiece is worn and before entering a hazardous environment. This check is to determine whether the wearer has correctly donned a facepiece before entering a contaminated work area. This pre-use seal check is not a substitute for a fit test.

What are the different types of Face-Fit Test?
There are two types of RPE fit testing - qualitative and quantitative methods.

Qualitative Fit Testing (QLFT) 
The Qualitative method is a pass/fail test based on the wearer’s subjective assessment of any leakage through the face seal region by detecting the introduction of a bitter- or sweet-tasting or fragranced aerosol as a test agent. The test subject will wear a hood for the duration of the test and the process relies on manual record-keeping and has a risk of operator error or subjective results based on an individual’s sense of taste and smell.

QLFT methods are suitable for disposable and reusable half respirators but are not suitable for full-face. This type of test is based on individual responses by the RPE wearer, and it is important that it is administered by a fit tester competent in using this method.

Quantitative Fit Testing (QNFT) 
A Quantitative method provides a numerical measurement of how well a facepiece seals against a wearer’s face, which is known as a Fit Factor. There are two types of QNFT methods: Controlled negative pressure (CNP) and ambient particle counting (APC).

CNP fit testing can be carried out in any environmental conditions, clean or dirty air, indoors or outdoors, as it measures the amount of air leaking out of the respirator when controlled negative pressure is applied to create a vacuum. CNP tests full- and half-face respirators but not disposables. It has no contamination issues or consumables and therefore offers low maintenance and cost of ownership.

APC requires specific indoor test conditions as the instrument counts the number of particles inside the respirator, compared to the number of particles external to the mask. If there is not enough particulate in the air, the tester will introduce artificial particulate by using consumables such as salt fog or alcohol wicks. APC is suitable for testing full- and half-face masks as well as disposable FFPs. It requires a certain level of maintenance due to particulate contamination of the unit as well as a need for consumables, so incurs an ongoing cost of ownership.

What are the pros and cons for each type of fit test?

Each method of fit testing offers different advantages, so it’s a matter of understanding the options available and selecting the right mask type and test method for applications on a case-by-case basis. The BSIF’s Fit2Fit scheme has produced a series of guides clearly explaining the different methods in detail, which are available on their website: The HSE also has extensive information on Fit Testing, which can be accessed on their website:

Shawcity is a distributor of the OHD QuantiFit2 CNP Fit Testing system in the UK and Ireland and is a member of the BOHS, BSC, BSIF and their Registered Safety Supplier Scheme (RSSS). 

Neil O’Regan is managing director at Shawcity, a member of the International Society for Respiratory Protection (ISRP) and is active within the UK fit testing community. For more information, visit