WHAT IS A MASK SEAL CHECK? AND ARE THEY RELIABLE?
- Rebekah McCutcheon
- Feb 25
- 5 min read
Updated: 6 days ago
If you've ever been fit tested or trained to wear a respirator, you've probably heard the term mask seal check - or fit check. But what actually is one, how do you do it, and most importantly: can you trust it?
In this article, we break it all down clearly so you know exactly what a mask seal check is, when to use it, and what it can and can't tell you about your respiratory protection.
What Is a Mask Seal Check?
A mask seal check (also called a user seal check or fit check) is a quick, self-conducted check that a respirator wearer performs each time they put on their mask. The goal is to confirm that the mask has been donned (put on) correctly and that there are no obvious air leaks around the face seal.
It is important to understand that a seal check is not the same as a mask fit test. A fit test is a formal, validated procedure conducted by a trained professional using specialist equipment - it determines whether a specific mask is the right size and model for your face. A seal check is a quick daily check you do yourself.
Under the Australian/New Zealand Standard AS/NZS 1715:2009, a user seal check is defined as "a very gross determination of fit" and should be performed just before entering a hazardous atmosphere.
The Two Types of Mask Seal Checks
There are two methods: positive pressure and negative pressure. Depending on your mask type, you may use one or both.
1. Positive Pressure Seal Check
Used for: N95s, P2 masks and most disposable respirators without exhalation valves.
How to perform it:
Place both hands over the respirator, covering the facepiece without pressing it flat against your face.
Exhale sharply and firmly.
The mask should balloon outward slightly and fill with air.
If no air escapes around the edges, the seal is good.
If you feel air leaking around the nose, cheeks, or jaw - re-adjust, re-mould the nose piece, and repeat.
Important: If your mask has an exhalation valve, do not use a positive pressure check - air will simply escape through the valve. Use a negative pressure check instead.
2. Negative Pressure Seal Check
Used for: Reusable elastomeric respirators and masks with exhalation valves.
How to perform it:
For disposable masks: place both hands over the mask and inhale sharply. The mask should collapse inward against your face and stay there while you hold your breath.
For reusable masks: cover the filter cartridges or inlet openings with your palms and inhale. The facepiece should collapse inward with no air rushing in around the edges.
If the mask caves in and holds - the seal is working.
If air rushes in around the edges - re-adjust and try again.
Are Mask Seal Checks Reliable?
This is where it gets important - and where we want to be straight with you.
Seal checks are a useful daily habit, but they have significant limitations. Here's what the research and Australian standards tell us.
What They Can Tell You
Whether you've donned your mask correctly - straps in the right position, nose piece moulded properly.
Whether there's an obvious air leak around the face seal.
That you're in the habit of checking your mask before entering a hazardous environment, which does reduce poorly fitted donnings over time.
What They Can't Tell You
Whether the mask is the right size or model for your face - only a formal mask fit test can determine this.
Whether very small or slow leaks are occurring - seal checks are not sensitive enough to detect minor leakage.
Whether the mask is truly fit for purpose - the AS/NZS 1715:2009 standard itself calls it "a very gross determination of fit."
In our experience working with thousands of people across Australia, many wearers genuinely believe their mask is sealed when it isn't - and vice versa. We've seen people confidently pass their own seal check and then fail a quantitative fit test, and others who feel uncertain about their seal only to achieve an excellent fit factor score.
Research supports this. A 2025 study published in Scientific Reports found extremely low levels of agreement between user seal check results and quantitative fit test results among healthcare workers - with agreement rates no better than chance. Similar findings have been reported consistently across multiple published studies.
The bottom line: Seal checks are a valuable daily habit and are required under AS/NZS 1715:2009, but they are not a substitute for a proper mask fit test. They catch obvious errors - not subtle ones.
Seal Check vs Fit Test - What's the Difference?
Seal Check | Fit Test | |
Who performs it? | The mask wearer (self-check) | A trained fit test operator |
When? | Every time the mask is donned | Before first use, then annually |
Equipment needed? | None | PortaCount or AccuFit machine |
What does it measure? | Obvious leaks from poor donning | Whether the mask is right for your face |
Is it validated? | No - gross check only | Yes - recognised under AS/NZS 1715:2009 |
Can it replace the other? | No | No - both serve different purposes |
When Should You Perform a Seal Check?
You should perform a seal check every single time you put on your respirator, without exception. This is a requirement under AS/NZS 1715:2009 and is standard practice in workplaces and healthcare settings across Australia.
This includes:
Before entering a clinical area or hazardous work environment
Each time you re-don your mask during a shift
After any adjustment to the mask, straps, or nose piece
If you've been touching your face or the mask during use
Frequently Asked Questions
Is a mask seal check the same as a fit test?
No. A seal check is a quick self-check you do each time you wear your mask. A fit test is a formal assessment conducted by a trained professional to confirm your mask is the right size and model for your face. Both are important and serve different purposes.
Can a seal check replace a fit test?
No. The AS/NZS 1715:2009 standard is clear that seal checks cannot replace a formal fit test. A seal check only catches obvious donning errors - it cannot tell you if a mask is fundamentally the wrong size or model for your face.
What if I feel air leaking during the seal check?
Re-adjust the mask. Re-mould the nose piece, reposition the straps, and repeat the seal check. If you cannot eliminate the leak, the mask may not be the right fit for your face. You should speak with your supervisor and consider booking a formal mask fit test.
How long does a seal check take?
Less than 30 seconds. It should be done every single time you put on your respirator before entering a hazardous environment.
Do I still need a fit test if I always pass my seal checks?
Yes. Fit testing is mandatory under Australian workplace health and safety standards for all workers required to wear tight-fitting respirators. Consistently passing a seal check does not confirm your mask is correctly sized or fit for purpose - only a formal quantitative fit test can confirm that.
Where can I get a mask fit test in Australia?
Fit Test Australia provides quantitative mask fit testing across Sydney, Perth, Randwick, Fairfield, Leederville, and throughout Australia. You can book online or find your nearest location here.
Ready to get properly fit tested? Don't rely on a seal check alone.
Related reading
