What is a respirator fit test?

What is a respirator fit test?

Using specialised equipment, a fit test is undertaken to determine if a tight-fitting respirator is capable of forming an adequate seal to the wearers face and checks that the seal is maintained through movement, deeming it suitable to be worn on the job. A fit test performs a range of exercises such as head movement, bending, talking or jogging to emulate an individual at work and challenge the seal in motion.   

Why do we need to fit test?

Fit testing is required by Australian New Zealand Standard AS/NZS17:15,2009 before a user wears a respirator on the job and should be assessed at least annually. In addition, fit testing should be undertaken whenever the wearer is issued another size, make or model, or if the wearer has had any significant weight fluctuation, changes in their facial features e.g. major dental work, facial reconstruction or a broken nose.

We undertake fit testing to determine how well our Respiratory Protective Equipment (RPE) forms a seal to our skin. If the respirator does not form an adequate seal, the wearer will potentially still be exposed to the very contamination they are trying to gain protection from. Air will always take the path of least resistance, if the wearer does not achieve an adequate seal, each breath the wearer takes, air will pull through any gap or leak present. The respirator should be selected in consultation with the worker to ensure individual fit, medical and psychological factors have been considered.

• Seal Obstructions

The AS/NZS17:15,2009 states that nothing is to obstruct the respirators’ ability to make contact with the wearers skin.

Possible seal obstructions that are preventable include jewellery, heavy makeup and facial hair. Facial hair can be detrimental when trying to obtain an adequate seal, it is especially important to not only be clean shaven (within the mask seal zone) for a fit test, but it is more important to maintain clean shaven skin whenever RPE is to be worn on the job.

• Compatibility with other PPE

Your respirator should not interfere with other Personal Protective Equipment (PPE) required on site such as, safety glasses, hearing protection, hard hats, face shields and coveralls. If your PPE is not compatible with your respirator it may obstruct the masks’ ability to form or maintain a seal whilst being worn on the job.

All PPE that is a requirement on site is to be worn during the fit test.

• Respirator Stability 

The better a respirator fits, the more stable the mask is likely to be on the wearer’s face at work. Fit testing determines the respirator’s ability to retain its seal when the worker is in motion. That’s why fit testing is made up of several exercises to emulate an individual at work. A respirator that shifts during movement may not be able to retain its seal.

• User Seal Check 

Individuals should perform a user seal check each and every time they don their tight-fitting respirator before entering into environments requiring the use of RPE. Fit testing ensures that the respirator is able to fit and provide an adequate seal, but a user seal check is an essential everyday test that ensures that the user has donned their mask correctly and is secure.

Users can either perform a positive-pressure or negative-pressure seal check:
 

A positive-pressure check means blocking the exhalation valve on a half or full facepiece respirator or covering the respirator surface on a filtering facepiece, usually by using your hands, and trying to breathe out. If slight pressure builds up, that means air isn’t leaking around the edges of the respirator.

A negative-pressure check involves blocking the intake valves on a half or full facepiece respirator or covering the respirator surface on a filtering facepiece, typically using your hands and trying to breathe in. If no air enters, the seal is tight.

It is always advised to follow the product User Instructions for more details.

The different methods of fit testing

Qualitative Fit Test Method (QLFT) 

A qualitative fit test is performed using a challenge agent within a controlled hood. This method replies on the uses senses to either taste or smell the test agent, to determine if a seal is achieved on disposable and half face reusable respirators. This method can be subjective.

Quantitative Fit Test Method (QNFT)

A quantitative fit test can be used to fit test all types of tight-fitting respirator. Using specialised equipment, it measures leakage around the face seal and produces a numerical result called a “fit factor.” The fit factor is the ratio of contamination air outside versus contamination air inside the mask. This method is objective.

• Controlled Negative Pressure (CNP) machine – using air pressure to determine if a seal has been achieved on half face and full-face reusable respirators.

• Condensation Nuclei Counter (CNC) uses ambient aerosol to measure particles inside the mask vs outside the mask to determine if a seal has been achieved on all P1, P2 disposable, half face and full-face respirators. e.g. PortaCount or AccuFit.

A fit factor of at least 100 is required for disposable and half-mask respirators and a minimum fit factor of 500 or 1000 for a full facepiece negative-pressure respirator depending on the protection factor required in use.  

When should you Fit Test?

When air monitoring has been carried out by an Occupational Hygienist and a contamination in the ambient atmosphere of the work environment is over the Work Safe Exposure standards (WES) that cannot be removed or replaced, RPE should be issued as part of the workplace Personal Protective Equipment (PPE) in order to minimise exposure to respiratory risk factors.

If the risk of exposure remains in the work environment above the Occupational Health and Safety recommendations, only your RPE will be able to provide the level of protection required to work in such contaminations. Your respirator will rely on an airtight seal in order to be effective, so it is necessary to ensure that tight-fitting respirators fit the user correctly in order to receive the masks intended protection.

Organisation in such circumstances, are required to implement a Respiratory Protective Equipment (RPE) program when issuing RPE within the workplace.

According to the applicable WHS Regulation, an RPE program should include:

• providing suitable RPE – 
  • the level of protection provided by the respirator must be suitable for the level of air contamination in the environment.
  • the filter in the respirator must be suitable for the type of airborne contaminants in the environment.
• medical screening of users of RPE
• training in the use, maintenance, and repair policy
• fit testing (if relevant to the RPE used).
• a facial hair policy for tight fitting respirators – facial hair can interfere with respirator fit by preventing some types of respirators from properly sealing to the skin.
• wearing of RPE (where required)
• correct cleaning and disinfection
• inspection, repair and maintenance
• storage of RPE to protect them from the elements
• record keeping
• program evaluation

To comply with the current Australian regulations, respirators must be made in accordance with AS/NZ17:16,2012 (the standard number should be displayed somewhere on the respirator or its packaging) and fit testing should be performed by a competent fit test specialist.

Respirator use in the workplace

Respirators are required in many workplaces within many industries and sectors. The CPBU and/or employers have an obligation to provide their employees with the necessary Respiratory Protective Equipment (RPE) to meet the requirements of their job. Safe Work Australia guidelines outline mandatory requirements for the use of respiratory protection in certain industries such as:

• Gas and Oil
• Concreting/stone works
• Building, construction and demolition
• Spray painting
• Coal mining
• Utilities
• Farming and agriculturalists
• Industries that deal with hazardous chemicals or fumes
• Healthcare sector
• Firefighters

Types of RPE

The types of Respiratory Protective Equipment (RPE) required in the workplace include N95, P100 and N99 masks, FFP1, FFP2, FFP3, half face and full-face elastomeric respirators, hood or helmet type full-face and half-face powered and non-Powered Air-Purifying Respirators (PAPR) and supplied-air respirators.

The respirators are divided into 2 main types

Air Purifying Respirators – Also known as filtering devices. These remove contaminants from the air using filters and can be powered or non-powered. These include the disposable, half face and full-face respirators.

Breathing Apparatus (BA) – This type of RPE provides an independent supply of air to the wearer, e.g. from a cylinder or compressor. These include the Powered Air Purifying Respirator (PAPR), Supplied Air Respirator (SAR), Self-Contained Breathing Apparatus (SCBA).

The selection of RPE will be influenced by the following factors:

• Contamination
• Task
• Operator
• Equipment limitations
• Special response HAZMAT incidents

The RPE should also be task related:

• Is the device for regular use or for emergency or rescue purposes?
• The probable length of time during which the wearer will be in the contaminated atmosphere
• The expected level of activity and mobility required of the worker
• The access to, and nature of the working environment and its location with respect a source of air suitable for breathing
• The need for clear vision and communication
• The facilities available to maintain the device if necessary

With many pathogens and contaminations in the workplace, choosing the correct mask and filters for the task are critical for workers health and safety.

Filtering facepieces (disposable respirators), also referred to as dust masks, are particulate filters, they are usually FFP1 or FFP2. Disposable masks only cover the wearers mouth and nose. It is important to note appropriate use of your P1 or P2 and what contaminations they should be used for. Some airborne contaminants include dust, mists, liquids and some fumes, but not gases or vapours.

Disposable dust masks are not suitable when:

• Contaminant concentrations are Immediately Dangerous to Life and Health (IDLH), if they are unknown or exceed the relevant exposure standard set by WES
• Not to be worn if toxic gases or vapours are present
• If a satisfactory fit cannot be achieved due to facial hair within the mask seal zone or other characteristics that prevent an effective seal between the edge of the mask and the wearer’s face
• If the atmosphere is deficient in oxygen (containing less than 19.5% oxygen by volume), within confined spaces or poorly ventilated areas

If there is a smell or taste of a contaminant and/or if persons in the area experience nose and/or throat irritation – some dust masks do have an active carbon layer added to reduce nuisance levels of organic vapours that can create unpleasant smells

An IDLH parameter is not considered an exposure standard. It is a concentration that may cause harm, rather than a concentration with no adverse effects expected. 

Types of contamination

Mechanically Generated Particles –

Examples of processes which would result in the mechanical generation of particles:

• Grinding
• Blasting
• Sanding
• Mixing powders
• Chipping
• Spraying

Some examples of mechanically generated particulates:

• Silica dust
• Coal dust
• Asbestos fibres
• Lead dust
• Sodium
• Hydroxide mist

P1 filters protect against mechanically generated particles. P1 filters are available as the powered type, replaceable filter type and disposable type.

Thermally Generated Particles –

Examples of work processes that would thermally generate particles:

• Smelting
• Welding
• Brazing
• Heating

Some examples of thermally generated particles:

• Lead fume
• Zinc Oxide fume
• Chromium fume
• Manganese fume
• Welding fume
• Bushfire smoke

P2 filters protect against mechanically or thermally generated particles (or both). P2 filters are available as the powered type, replaceable filter type and disposable type.

Gas and Vapours

Some examples of gases and vapours:

• carbon monoxide (CO)
• chlorine
• nitrogen dioxide
• phosgene
• hydrogen sulphide (H2S)

P3 filters are to protect against highly toxic or irritant particles. Protection against gases and vapours may be obtained by the use of air-purifying RPE or by a supplied-air device. To achieve P3 filter classification a full-face piece is required (for non-powered air), or a head covering or full-face piece for a Powered Air Purifying Respirator (PAPR). P3 filters are available as the powered type and replaceable filter type.

It is important to note that if a P3 filter is used in conjunction with a half face piece, the protection level is equivalent to a P2 filter.

Protection against oxygen-deficient atmospheres

Entry to places where oxygen levels have been depleted or is unknown requires either the wearing of

• a Self-Contained Breathing Apparatus (SCBA) of sufficient operational duration; or
• air-line RPE with escape SCBA attached to the person

It is advised that particular care should be taken when choosing an air-line or air-hose equipment, limitations should be considered along with working in confined spaces.

If you are ever required to wear any form of respiratory protection, please ensure you get fit tested by a RESP-FIT accredited fit tester.

References

AS/NZ17:15,2009 Standards, ISO 16975-3:2007, SafeWork Australia