Qualitative and Quantitative Face Fit Testing: What You Need To Know
Face fit testing for RPE (Respiratory Protective Equipment) is essential for those who use tight-fitting respiratory equipment to stay protected from respirable hazards. Fit testing ensures that the facemasks and/or respirators worn by workers are capable of providing adequate protection against respiratory hazards within the workplace.
Qualitative Vs Quantitative Face Fit Testing
The UK has specific requirements for face fit testing established by the HSE.
To ensure the RPE is up to the required standards, face fit testing must be conducted by a competent person, according to either qualitative or quantitative methods. Here is everything you need to know about the difference between qualitative and quantitative face fit testing.
Qualitative Face Fit Testing: The Taste Test Method
Qualitative face fit testing uses the subject's own perception (usually taste, hence “taste method”) to determine whether a mask fits correctly. This should not be confused with a “pre-use seal check” where a trained tester will show the user how to properly wear their mask and then ask them to rate the fit based on comfort, breathing resistance, and more. A successful test requires that all criteria be met before the worker can continue using their RPE.
A correct qualitative fit test uses the wearer’s sense of taste to ensure there is not too much leakage from around the face seal of a facemask when in use, by asking the wearer to detect the presence of a harmless challenge agent, usually an aerosolised test solution to replicate the presence of airborne contaminants in a live use situation. They should be asked to undertake a series of movements and “exercises” to challenge the mask seal, the extent and duration of which are documented in the fit test protocol being followed (HSE INDG 479 in the UK).
Pros of Qualitative Face Fit Testing
- Apparent lower cost than quantitative testing. Qualitative fit test kits are readily available, cheap, and relatively easy to use; however, to ensure the test is conducted accurately the operator should undertake some training and demonstrate competence in the ability to perform a fit test.
- The test result is a pass or a fail based on the person's taste response. No complicated calculations are required, the wearer tastes the challenge or they don’t, simple!
- No power is required; qualitative fit testing can be undertaken anywhere, and the kit is very light, compact and portable.
Cons Of Qualitative Face Fit Testing
- Cannot be used to verify the fit of full-face masks due to not being sensitive enough to measure the small amount of leakage, so to confirm that a full-face mask fits adequately.
- The wearer may not be able to taste the challenge agent, leading to a false pass. This can be for many reasons as individuals' taste sensations are variable and often influenced by other factors such as illness, past head trauma, covid-19, or if the person is a smoker.
- Lack of accuracy due to human error and/or insufficient training. If the fit tester does not generate enough challenge, then the wearer will not taste it; the assumption is likely to be that there is no leakage when in reality there was nothing to leak in. The risk of a false pass result is very high.
- The qualitative fit test provides a subjective impression of a correct fit (or not) and not an exact numerical analysis. The Fit is “assumed” based on the null response to the challenge agent, which is assumed to be a result of a correct fit.
Quantitative Face Fit Testing: The APC Method
An alternative to the qualitative test method - and some may say a more accurate means, is a quantitative method which quantifies (measures) the fit and does not rely on the wearer’s taste response. The most common means of doing this is by using an Ambient Particle Counting device, such as an AccuFIT or PortacountTM.
The APC method is conducted using an ambient particle counting device (APC). If particles are detected inside the face mask, this indicates that there are leaks in the seal between the skin and RPE.
Other technologies use changes in pressure to measure changes in mask leakage. Look out for future blog articles around this method to learn more.
Quantitative testing depends on objective particle measurements and real-world data, and for this reason is preferred by many industrial users, as it doesn’t require the subjective input of the wearer as to how well their mask fits their face.
Pros of Quantitative Face Fit Testing: The APC Method
- Can be used with all types of face masks such as N95, FFP1, FFP2, and FFP3 as well as full and half facemasks.
- Does not depend on the subjective perception of the wearer. The APC device measures and reports an objective leakage measurement that does not need to be based on taste.
- Results can be determined quickly or immediately, displayed on a screen, and the effects of any adjustments to the fit of the mask are reported in seconds.
- Some see this as a more accurate means of testing than qualitative tests.
- Tests can be repeated without needing additional preparation time due to not having to rely on cleaning the wearer’s palate between each test.
Cons of Quantitative Face Fit Testing: The APC Method
- Results may vary due to environmental factors – e.g., the presence of insufficient airborne particles may lead to void results or false passes in some lower-end devices.
- More expensive setup – quantitative testing requires an investment in technology, software, and training to deliver the required results.
Making The Right Choice
Achieving an effective seal between the user’s skin and their respiratory protective equipment (RPE) requires careful assessment that meets UK health and safety regulations for workplace safety. An inadequate RPE fit can expose the user to severe safety risks from respirable hazards in their work environment.
Qualitative or quantitative face fit tests should therefore both be considered when assessing RPE. However, despite the higher setup costs, quantitative methods ultimately provide better value and accuracy by removing the variables of individual sense perception and human error from the process, allowing better risk mitigation and operational safety.
If you have any enquiries about face fit testing and how to get the best results for your workers, please contact us today.
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