Which Face Fit Testing Method Should I Choose?

02 Oct Which Face Fit Testing Method Should I Choose?

So, which face fit test method should I choose? People are easily confused when it comes to choosing the right face fit testing service.

The first thing to consider, is the person I am employing to do this vitally important job actually competent to do so?

Fit2Fit Accreditation

Anybody who conducts a face fit test must be competent as defined in the HSE’s INDG479 document. Competence can be demonstrated by achieving accreditation by the BSIF (British Safety Industry Federation) Fit2Fit accreditation scheme.

You do not have to use a Fit2Fit accredited tester. But then you have to ask yourself, how do I know this tester is competent?

We are Fit2Fit accredited for both qualitative (taste test) and quantitative (ambient particle counting) face fit testing. We are also proud members of BSIF.

Difference between qualitative and Quantitative

So what is the difference between qualitative and quantitative testing. And which face fit test method should your fit tester use?

A qualitative face fit test is a simple taste test. The test subject is initially tested with a weak version of the test solution (sensitivity solution). Tested without a mask on, to prove that they can detect the test solution. And also to see how sensitive they are to the taste.

Qualitative Face Fit Test

There are 2 options for the taste test. Either bitter or sweet tasting solutions. So, if the test subject can’t taste the bitter solution, there is a sweet one instead.

If neither can be detected by the test subject they must be tested by the quantitative method.

Once the test subjects ability to taste the test solution and sensitivity level has been established, the test subject is asked to drink some water, wipe their hands and mouth. They are then asked to fit their mask.

Once the mask is fitted the tester will explain the test process. And then explain and demonstrate the 7 test exercises:

• Normal Breathing
• Deep Breathing
• Head Side to Side
• Head Up and Down
• Talking
• Bending
• Normal Breathing

Each exercise lasts for exactly 60 seconds. If the test subject detects the test solution, then the test has failed. The entire test has to be repeated after waiting for 30 minutes.

The qualitative test is a valid test method which is approved by the HSE and is relatively easy to do and the test kits only cost about £150.

The qualitative test is not without its problems. Firstly, we are relying on honest responses from the test subject as to if they can taste something or not.

Most people are honest. But in our experience, we have had times where the test subject tells me they can’t taste the solution but their face is telling a different story. After all bitrex tastes pretty disgusting.

Another problem is sensitivity to the solutions. If they can’t taste either of the solutions. Or, have very low sensitivity to them, this can also create issues achieving positive results. We have heard some testers have resorted to using the strong test solution to test for sensitivity.

inadequate Qualitative testing

The test must be conducted properly in the first place. We have witnessed on several occasions over the years testers not doing all 7 exercises. Or not doing them for the full minute, or making up their own!! The test protocol is clearly defined in INDG479 and there is no other way to do the test.

The way the hood is fitted for the test is also an issue to consider. The hoods hold a specific volume of air and should always be fitted properly.  The hood should not have any folds. Or pushed down parts. So as not to decrease the volume during the test. With some masks, the hoods don’t allow for easy head movements during the test.

Qualitative testing can be conducted on half mask respirators only, this method cannot be used to test a full face respirator.

All of this said, most of these issues can be dealt with by a competent fit tester. But this is why we prefer to use the quantitative method of testing instead.

Quantitative face fit test

There are 2 methods of quantitative face fit testing. There is APC (Ambient Particle Counting) or CNP (Controlled Negative Pressure) testing. We are going to look at the APC (PortaCount) method. As this is the method that we are accredited for.

Quantitative Ambient Particle Counting face fit testing uses specialist equipment. Most commonly the TSI PortaCount machine or the AccuFit machine which costs around £7000.

The AccuFit and PortaCount counts particles in the ambient air.  By using adaptors the machine is able to sample the air from inside the test subjects mask while it is being worn. The machine then works out how much cleaner the air is inside the mask compared to the air outside of the mask. The APC machine gives us a numerical result called a fit factor.

This method does not rely on the honesty of the test subject. The machine tells us if it is passing or failing not the test subject. However we do rely on having a high enough particle count in the room to start with. If the air is too clean then we do have methods that we can use to increase the particle count in the room.

There is no issues with sensitivity for the quantitative test. We are not using a test agent, the machine is using the air in the room as the test agent.

The APC machine uses the same 7 exercises that are used for the qualitative test. The only differences are the exercises last for 80 seconds instead of 60 seconds and physical exercise is included (normally an aerobic step).

None of these exercises can be bypassed or the test times altered. The machine tells you on the screen which exercise you should be doing.

There is no hood worn during this test. So no problems with this been fitted correctly. However it is important that the mask adaptors and sampling tubes are used and fitted correctly.

If the test fails we don’t have to wait 30 minutes for a re-test. We can make the necessary adjustments and start a new test so it is much more efficient.

The APC machine can test all mask types: disposable, reusable half mask, full face mask, SCBA etc. However the standard AccuFit and PortaCount machines can only test P3 filters not P1 or P2. But why would you want to use anything but P3 anyway?

face fit testing

I hope the above answers which face fit test method to choose. Any professional face fit testing company should have the ability to competently carry out both qualitative or quantitative face fit testing and should always carry out the most appropriate testing for you. Still have questions? Contact our experienced team for more information today.