MASK FIT TESTING AND FIT CHECKING - WHAT’S THE DIFFERENCE?
- Rebekah McCutcheon
- Feb 19
- 13 min read
Understanding the difference between a Mask Fit Test and a Mask Fit Check
At Fit Test Australia, we know the world of mask fit testing and fit checking can all be a bit confusing, and we’re here to explain it all, allay any worries and get rid of any of the myths.
Fit checks often get confused with fit tests or vice versa, it is important to distinguish the difference as both have a place in protecting your respiratory health.
A fit check is also known as a ‘user seal check,’ according to the AS/NZS 1715:2009 standards, which state it as “A very gross determination of fit.” However, it also states that ”The wearer should use these fit checks just before entering the hazardous atmosphere."
What Is Mask Fit Testing and Fit Checking?
As simply as we can get:
A fit test is used to determine if the mask is the correct size, make, or model and if an adequate seal was achieved and maintained during motion.
A fit check is self-conducted by the wearer after donning their respiratory protective equipment (RPE) to ensure they have donned (put it on) correctly and achieved the appropriate seal by feeling for noticeable air leakage each time they wear it prior to entering the hazardous area.
And let’s be very clear: a fit check should never be used in place of a fit test. These should not be confused as they are two completely different things. Mask fit testing is the first step to ensure a respirator is suitable for personal use prior to issue, and fit checking is the ongoing personal check.
The AS/NZS 1715:2009 standards are also quite clear on the requirement for tight-fitting respiratory protective equipment (RPE) to be fit tested initially on issue and annually thereafter.
Mask fit testing should not be confused with a fit check, as they are two completely different checks.
Key Differences Between A Fit Test Versus A Fit Check
A fit test is the only validated method used to properly determine that a wearer has been issued the correct size, make or model of Respiratory Protective Equipment (RPE). The goal is to ensure the respirator is ‘fit for purpose’ for each individual wearer as all our faces are unique, and not everyone will fit the same size, make, or model issued.
A quantitative fit test (QNFT), considered the ‘gold standard’, is an objective method of fit testing RPE, it measures leakage numerically from outside the respirator versus inside the respirator to determine an appropriate fit. If too much leakage is calculated inside a respirator, it will fail the fit test. A poorly fitted respirator has air bypassing the filters, keeping the wearer exposed.
A fit check, aka 'seal check,' is a self-check using either positive or negative pressure to determine you have achieved an adequate seal, most RPE allows you to conduct both positive or negative pressure checks, although with some respirators, it may be easier to use either just a positive or a negative check due to the respirators design.
Once a respirator successfully passes a fit test, a wearer should conduct a ‘fit check’ each time to ensure they have put on the respirator correctly prior to entering a hazardous atmosphere where airborne contamination has been recognised.
A fit check is a brief assessment to ensure that the respirator is correctly positioned on the face and has formed a proper seal, and no overt air leakage should be felt/detected by the wearer. It's a simple but essential aspect of any workday.
Wearing your respirator in line with manufacturer recommendations and how you were trained should result in repeatability of wear.
Repeatability is key.
Note: A fit check is not a validated method to ensure a respirator is ‘fit for purpose’.
Why Do We Conduct a Fit Check?
Despite their simplicity, the AS/NZS 1715:2009 standards state, “These tests have significant limitations. The primary concern is that the wearer might adjust the respiratory protective equipment after it has been positioned on the face, which could compromise the facial seal”.
That being said, you should conduct your mask fit check, otherwise, you may not have it positioned correctly, or the straps may not be as tight as they need to be to firm and hold the seal effectively.
If the respirator has been mask fit tested, it has already been established you are wearing the correct size and that the respirator is deemed ‘fit for purpose’ as it passed ‘mask fit testing.’ The purpose of ongoing ‘fit checking’ is to make sure you have adequately sealed your own mask each time you wear it.
Just as all PPE is subjective, fitted RPE is also subjective post fit testing as it relies on the wearer to wear it correctly each time. The ideal outcome is to ensure the wearer can replicate wearing their respirator to the same standard in which they would have successfully passed their fit test.
What Types Of Masks Need a Fit Check?
It is only practical to fit check tight-fitting respirators, as you can only fit test tight-fitting respirators, these include N95 and P2 disposable filtering facepieces, half-face and full-face elastomeric respirators, and tight-fitting Powered Air Purifying Respirators (PAPR), Self Contained Breathing Apparatus (SCBA) and Airline Respiratory Protection.
Let us be clear again: Fit checks are not a substitute for a fit test.
Positive and Negative Pressure Fit Checks
Respirators can be classified as either "positive-pressure" or "negative-pressure." Most air-purifying respirators are negative-pressure, whereas supplied-air respirators and self-contained breathing apparatus (SCBA) can be either positive or negative-pressure.
In a positive-pressure respirator, the air pressure inside the face piece is consistently higher than the surrounding atmospheric pressure. In contrast, a negative-pressure respirator relies on the user's inhalations to create a lower pressure inside the face piece compared to the outside air and pulled into the airways.
For reusable masks, you will be blocking the air entry or exit points to conduct either a positive or negative fit check.
Negative Pressure Fit Checks P2/N95
Disposable Respirators
In the healthcare sector, some states may have minor variations in how they perform their N95/P2 fit check. Fit Test Australia will be referring to the NSW HealthShare way of conducting a fit check.
Fit checks vary slightly between brands and styles, please be reminded this is a general guide, and you should always refer to the manufacturer's recommendations on how to fit check your P2/N95 respirator.
To perform a negative pressure fit check with a disposable respirator:
Don the respirator and ensure the top strap is above the ear placed on the crown and the bottom strap below the ear on the nape of the neck.
Make sure no straps are twisted, and conform the metal bar over the bridge of the nose to have no gaps. Mould with both hands using your fingers; don’t use one hand to pinch the nose bridge.
Completely cover the respirator with both hands cupped, try not to disturb the fit.
Gently move hands towards the respirator's edge.
Inhale sharply and hold your breath for a few seconds, feel for the air leakage.
If the face piece collapses noticeably with a vigorous breath, this indicates an adequate seal.
If you feel air leaking through any gaps, re-adjust the respirator, check the straps, remould the nose-piece again, and perform another fit check until you achieve a proper seal.
If after readjusting and remoulding you continue to fail the fit check, do not go to your clinical/work area, speak with your supervisor. View helpful tips here.
Positive Pressure Fit Checks P2/N95
Disposable Respirators (without exhalation valves)
Positive pressure fit checks are suitable only for tight-fitting respirators. The following methods outline how to perform these checks:
Fit checks vary slightly between brands and styles.
Please be reminded this is a general guide, and you should always refer to the manufacturer's recommendations on how to fit check your P2/N95 respirator.
To conduct a positive pressure fit check on disposable respirators, follow these steps:
Don the respirator and ensure top strap is above the ear placed on the crown and the bottom strap below the ear on the nape of the neck
Make sure no straps are twisted and conform the metal bar over the bridge of the nose to have no gaps. Mould with both hands using your fingers, don’t use one hand to pinch the nose bridge.
Completely cover the respirator with both hands cupped at the front, try not to disturb the fit.
Breathing in and out, gently move hands towards the edges of the respirator.
Start by placing your hands above the nose bridge, exhale, move hands to either side of the facepiece, exhale again and then move hands under your jaw, exhale again. Each hand movement should have the wearer exaggerate their exhaled breath to fit check all the edges, feeling for the leak.
During the exhalation, the mask should expand and inflate with air. If no air escapes around the edges, the seal is effective.
If you feel air leaking through any gaps, re-adjust the respirator, check the straps, remould the nose again perform another fit check (user seal check) until you achieve a proper seal.
Persistent air leakage felt as a light sensation of air in the wearers eyes or a whisper across the skin, and the mask does not inflate, the respirator has failed the positive pressure fit (seal) check.
If a fit cannot be achieved, do not go to your clinical/work area, speak with your supervisor.
Another great example of how to perform a fit check can be found in the Queensland Government Metro North Hospital Service.
Some disposable respirators fit check differently, an example is the 3M 1860 cup as it is stiff and will not inflate or deflate with a fit check, the wearer will rely solely on feeling the leakage.
If you want to know how to don and fit check P2 and N95 respirators, or how to fit check P2 and N95 respirators we can help guide you at one of our mask fit testing appointments.
Reusable Half and Full Face Respirator Fit Checks
Reusable respirators also known as 'elastomeric masks', come in half face or full face options.
The principles that apply to the fit checking half-face respirators also apply to full-face respirators.
Don (put on) the respirator, position the respirator to be comfortable with your chin cupped in the facepiece, place the top head strap on the crown above the ear, the bottom strap always below the ear on the nape of the neck. Tighten the straps enough to ensure the respirator will be securely held onto your face, it should be tight enough to hold it study in place but not too tight otherwise it may cause discomfort. Over-tightening can also lead to headaches, one would naturally loosen the straps which may result in the seal no longer being appropriate.
The desired outcome is to block either the air entry or exit point/s, this action will result in either a positive or a negative fit check depending which point you block.
Fit checks vary slightly between brands and styles, please be reminded this is a general guide, and you should always refer to the manufacturer's recommendations on how to fit check your elastomeric respirator.
Negative Pressure Fit Check
Reusable Respirators
Follow these steps for a negative pressure fit check:
To conduct a negative pressure check, you need to block the intake of air by covering the filter/s or cartridges.
The wearer shouldn’t be able to inhale momentarily, hold your breath for a few seconds.
The facepiece should collapse slightly.
If the facepiece stays slightly collapsed and you do not detect any inward leakage or hear the air pass, the respirator is adequately sealed/fitted, and the fit check is complete.
If you experience the sensation of air passing or the respirator does not collapse appropriately, readjust the respirator's position on your face, and/or tighten the straps ever so lightly, and conduct another fit check.
If the respirator is unable to demonstrate an appropriate seal and fails after multiple fit check attempts, inspect the respirator to ensure all membranes are on correctly and in working order, check the respirator has no visible damage, nor is the seal distorted/warped from poor storage which may result in an inadequate seal being able to be achieved (see image).
Damaged Seal vs New Seal
Do not wear your respirator in a hazardous atmosphere. If it cannot pass a fit check, speak to your supervisor.
Tips to be mindful of:
If you do not properly close/block the filters, the respirator may not collapse as expected and display the desired ‘fit’ outcome, as air may still pass through the improperly blocked/closed filters.
Use the palm of your hand for a Sundstrom (see below image) for 3M squeeze
closed 3M 6035 hard case filters (as pictured above), for pancake filters push firmly on the filters surface blocking the intake of air (where the filter connects to the respirator).
A Negative Pressure Fit Check on a Sundstrom SR100
Positive Pressure Fit Check
Reusable Respirators
Follow these steps for a positive pressure fit check:
Close off the exhalation valve with the heel of your hand or palm. Never use your fingers, as air can still pass through the gaps between your fingers.
Exhale sharply into the facepiece.
The facepiece should expand slightly.
If you experience air passing or the respirator does not expand appropriately, then readjust the respirator's position on your face, and/or tighten the straps ever so lightly and conduct another fit check.
The fit is considered satisfactory if a slight positive pressure builds up inside the facepiece without any outward leakage.
If the respirator is unable to demonstrate an appropriate seal and fails after multiple fit check attempts, inspect the respirator to ensure all membranes are on correctly and in working order, check the respirator has no visible damage, nor is the seal distorted/warped from poor storage which may result in an inadequate seal being able to be achieved.
Do not wear your respirator in a hazardous atmosphere. If it cannot pass a fit check, speak to your supervisor.
Tips to be mindful of:
It is important to note this is an initial check, and if the wearer persists to exhale after the initial indication of pressure built up, you may eventually force air through, which may have the wearer think the fit is not satisfactory when it may have been adequate.
If you push too hard on the respirator, trying to block the exhalation outlet, you may distort the seal/fit and fail the fit check as air passes through the gaps from the unnecessary pressure applied.
Positive Pressure Fit Check 3M 6000 Half Face
Why You Shouldn’t Substitute Mask Fit Testing with a Fit Check
A fit check should never be used as a substitute for mask fit testing.
Just to drive it home, mask fit testing validates the use and issue of a particular size, brand, or model RPE, while a fit check ensures you are wearing it correctly each and every time in the workplace.
Passionate about your respiratory health, Fit Test Australia’s preferred method of mask fit testing is quantitative fit testing (QNFT), which maintains an objective test result for the wear's best respiratory protection. The equipment is designed to calculate the ambient air per cubic centimeter. The equipment’s scientific name is a Condensation Nuclei Counter (CNC). This objective measurement of leakage is sensitive enough to ensure the wearer achieves the respirator's full level of intended protection. Controlled Negative Pressure (which can only be used for elastomeric respirators) is another form of quantitative fit testing; both instruments have a bonus ability to fail poor-quality or damaged respirators.
Again, a fit check is not a validated method to ensure a respirator is ‘fit for purpose’.
A wearer may never detect the subtle micro leaks that quantitative fit testing may flag. It is the respirable particles that cause the most damage to your lungs.
As Australia’s leading fit test service provider, our data reflects wearers that may pass a ‘fit check and a fit test,’ but the results can sometimes be dismal and display a pass, but sometimes only just. From our experience, wearers are not always the best judge of a ‘good fit.’
Measuring a leak allows a competent ft tester to make an educated decision to accept low results or retest alternative sizes or styles to ensure a more suitable fit is achieved to safeguard the workers’ health. This is another reason why FTA will not encourage or endorse qualitative fit testing; there is no way of knowing if someone may only be ‘just’ passing or if a more suitable size or style should be tested to achieve a better fit factor result (final leakage score) for the wearer.
Left: A 3M 6000 half-face respirator scoring a satisfactory but rather low fit factor result (335).
Right: The same 3M 6000 half-face respirator, although FTA tested the wearer into a smaller size, achieving an outstanding high fit factor result (49358).
What is a Seal Check?
A “seal check” is effectively the same as a fit check. You may have heard of doing 'seal checks' (aka fit checks) on respirators such as N95s, P2s, and reusable elastomeric masks.
A user seal check (not to be confused with a fit test) is performed to determine if the respirator has been donned (put on) properly and check for overt air leakage around the facepiece.
The user seal check can be a positive pressure or negative pressure check - or both.
Are Seal Checks a Reliable Way to Check the Fit?
Just so we’re totally clear, sometimes you will hear the phrase “seal check” - this is exactly the same as a “fit check”; a different phrase but the same meaning!
Remember: seal checks are never a substitute for mask fit testing.
Fit testing is a requirement for all tight-fitting respirators under the AS/NZS 1715:2009. You can book in for a quantitative mask fitting test at Fit Test Australia- we have offices for fit testing in Victoria and New South Wales.
Know Your Fit Factors
Check our respirator fit factors blog to get some more details about what fit factors mean.
Fit checking is designed to determine an obvious misfit so that the wearer can adjust according to the obvious leak detected. Again, once fit tested into the respirator, a fit check is a step implemented to aid the wearer in that the seal is or isn’t appropriate so they can adjust and correct the fit/seal accordingly.
Relying on a fit check in place of a fit test may have workers still exposed, working with a false sense of health and safety in a hazardous atmosphere.
Research consistently demonstrates that seal checks are unreliable, particularly for disposable respirators, and offer little predictive value. With offices in Victoria and New South Wales, we conduct thousands of mask fit tests across Australia each year. So when we say that seal checks are not an accurate way to determine whether someone will pass or fail a quantitative fit test, we speak from extensive experience being specialists in this fit testing.
Many people struggle to detect air leaks during positive or negative pressure seal checks. Time and again, we’ve seen individuals who are certain their mask fits perfectly fail a quantitative fit test, while others who suspect a leak pass without issue. It’s a bit like judging a car’s performance just by listening to the engine—what seems fine on the surface isn’t always an accurate measure. This unpredictability highlights why seal checks alone aren’t sufficient. A proper fit test is the only reliable way to ensure your respirator is protecting you effectively.
Fit Test Australia - Leading Education in Mask Fit Testing
At Fit Test Australia, we pride ourselves on educating individuals on performing seal checks according to international fit testing standards, including AS/NZS 1715:2009. Our training also covers correct donning, doffing, filter change, cleaning, and storage. It’s crucial to remember, however, that seal checks should never replace a proper fit test. Fit testing remains the only reliable method to ensure that a respirator provides the necessary protection.
Your health and safety is our priority
Call: 0403 064 064 or 0407 487 422
Email: info@fta.net.au
FTA fit test Melbourne Victoria and Sydney NSW
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