02 Oct Which Face Fit Testing Method Should I Choose?
People are easily confused when it comes to choosing the right face fit testing service. So, which face fit testing method should you choose?
The first thing to consider, is the person I am employing to do this vitally important job actually competent to do so?
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?
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) without a mask on, to prove that they can actually detect the test solution and also to see how sensitive they are to the taste.
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 we can use the sweet one instead.
If neither can be detected by the test subject then they have to be tested by the quantitative method.
Once the test subjects ability to taste the test solution and sensitivity level has been established then 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 then explain the test process then explain and demonstrate the 7 test exercises:
- Normal Breathing
- Deep Breathing
- Head Side to Side
- Head Up and Down
- Normal Breathing
Each exercise lasts for exactly 60 seconds and if the test subject detects the test solution then the test has failed and the entire test has to be repeated after waiting for 30 minutes.
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 my experience I have had times where the test subject is telling me that they can’t taste the test solution but their face is telling me 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, then this can also create issues with achieving positive results and I have heard that some testers have resorted to using the strong test solution to test for sensitivity.
The test not being conducted properly in the first place. I have witnessed this on several occasions over the years where testers are not doing all 7 exercises, 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 with no folds or pushed down parts so as not to decrease the volume during the test and 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.
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 which costs around £7000.
The PortaCount counts particles in the ambient air and by using adaptors is able to sample the air from inside the test subjects mask while it is been worn, the machine then works out how much cleaner the air is inside the mask compared to the air outside of the mask then 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 but 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 PortaCount uses the same 7 exercises that are used for the qualitative test, the only differences are that 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 on the PortaCount and 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 PortaCount can test all mask types: disposable, reusable half mask, full face mask, SCBA etc. however the standard PortaCount can only test P3 filters not P1 or P2 but why would you want to use anything but P3 anyway?
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. Contact our experienced team for more information today.