What is Respirator Fit Testing?
Respirator fit testing is designed to detect air leaks around the seal of the respirator and the wearer’s face. If the respirator doesn’t fit correctly, it won’t provide the intended level of protection and will leave the wearer exposed to contaminated air. This could result in immediate or long-term health effects.
Why is Respirator Fit Testing Important?
Respirator fit testing is essential for ensuring adequate protection. Fit testing is used to check that a respirator forms an effective seal on an individual's face, minimising the potential for contaminated air to pass through gaps or leaks. A proper fit is crucial for the respirator to perform its intended function of protecting the wearer from hazardous airborne contaminants.
Fit testing is also a requirement under the Australian New Zealand Standard AS/NZS1715:2009 for employees wearing tight-fitting respirators, including disposable and reusable respirators.
Types of Respirator Fit Tests
People’s faces differ drastically in terms of both shape and size, which is why there are different styles and sizes of respirators. Respirator fit testing is to be carried out by a competent person and is used to identify a suitable respirator for an individual. A competent person could be an occupational hygienist, manufacturer, supplier, consultant, or a trained in-house person. Workers must pass a respirator fit test before wearing a tight-fitting respirator on the job for the first time. It is worth noting that a fit test should not be confused with fit checking. Fit checking is the process of ensuring that the respirator is properly positioned on the wearer’s face to create a good seal. A fit check is a quick check that should be carried out each time the wearer dons their respirator.
There are two fit test methods that meet the Australian New Zealand Standard AS/NZS1715, quantitative fit testing and qualitative fit testing. Here’s how these two approaches work.
Quantitative Fit Test (QNFT)
The quantitative method is the most reliable method of fit testing, making it the gold standard fit test. The quantitative fit test provides a numerical measure of how well the respirator fits against the wearer’s face, known as a ‘fit factor’. This method is suitable for tight-fitting respirators, including single-use and re-usable half-face respirators, full-face respirators and powered air-purifying respirators (PARPs). Quantitative fit testing procedures use specialised equipment, like a laboratory test chamber or a portable fit testing device, to conduct the test.
The most common technique is known as the ambient aerosol condensation nuclei counter (CNC) method. It uses a particle-counting device to measure the concentration of particles both inside and outside the respirator while the wearer performs various exercises. By comparing the particle concentrations, an objective numerical fit factor is calculated, which determines the respirator's fit.