Qualitative v. Quantitative Respirator Fit Testing

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6 December 2022 >> , , , ,

Qualitative v. Quantitative Respirator Fit Testing

Qualitative v. Quantitative Respirator Fit Testing

TAKEAWAY: Delve into the differences between qualitative and quantitative respirator fit testing including the pros and cons of each test and tips for choosing the right test for your workforce.

By Jennifer Crump

Fit testing is critical to ensuring the health and safety of your workers. Without a tight fit, the respirator cannot do its job and protect the worker. There are 2 types of respiratory fit testing: qualitative and quantitative. Here is how to decide which is better for your workplace. 

Qualitative and quantitative respirator fit testing defined

Qualitative fit testing (QLFT) assesses the effectiveness of a respirator when a specific employee wears it. It is also referred to as mask fit testing and is leveraged when a worker must use a tight-fitting respirator in the workplace. It leverages users’ taste and smell to detect leakage using specific chemicals. If the wearer can taste the chemical, the respirator fails the test. 

Quantitative fit testing (QNFT) is another type of mask fit testing used to determine whether a respirator properly fits an employee. This test objectively measures leakage amount (quantity) using a specific machine or software that calculates the measurements. It does not rely on human taste. 

Pros and cons of qualitative and quantitative fit tests

Qualitative Fit Testing: Pros and Cons

Low equipment costsChance of misinterpretation or deception
Pass/Fail ResultsMaximum fit factor of 10
Fast – multiple people can be tested at the same timeSubjective
Errors can be made by test subject and tester

Quantitative Fit Testing: Pros and Cons

No protection-factor limitEquipment is costly to set up 
Documentation of numeric resultsRequires face piece or probe adapter
No chance of misinterpretation, or deceptionAnnual recalibration of equipment
Ease of useOnly one subject can be tested at a time

How to perform a qualitative fit test

In a QLFT, workers wear the mask they intend to wear during the workday and are exposed to ambient air containing non-toxic airborne chemicals. Typically, the tester will leverage one of four chemicals designed to trigger a sensor reaction when breathed in through any leaks in the mask. These include isoamyl acetate, which has a fruity aroma, saccharin solution, which has a sweet taste, Bitrix, which has a distinctive bitter taste or stannic chloride, which is a smoky irritant. During the test, the worker will generally be asked to breathe normally and deeply while bending over and talking. The QLFT should simulate conditions the worker will typically encounter while wearing the mask. 

How to perform a quantitative fit test

A quantitative fit test (QNFT) uses a hose inserted into the face piece of the mask while the user is wearing the mask, which delivers various air samples to a separate device for analysis. This testing procedure results in a numeric value for the level of contaminants within the mask. This numeric value is then compared to the concertation of contaminants outside the mask and results in a fit factor. The fit factor indicates the level of any leakage that exists when the worker wears the mask. 

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6 Tips for choosing the right type of respirator fit test for your needs 

While most North American safety authorities allow quantitative and qualitative fit testing, knowing which test is suitable for your workers is more challenging. For example, qualitative testing is typically used for half-facepiece respirators, while quantitative testing can be used for both half- and full-facepiece respirators.

Here are 6 tips for choosing the right type of respirator fit test for your needs:

1. Know the guidelines and legislation of the province and state you work in.

Both provincial legislation and the Canadian Standards Association mandate fit testing in Canada. In the U.S., the Occupational Health and Safety Administration and the National Institute for Occupation Health and Safety set the standards for fit testing. However, some states also maintain additional requirements. 

These legal requirements can be relatively complex and speak directly to the need for testing and the specific type of testing that may be required. For example, according to the OSHA 1910.134(f)(6) provision, qualitative fit testing “may only be used to fit test negative pressure air-purifying respirators that must achieve a fit factor of 100 or less.”

2. Consider the costs of equipment and training.

Quantitative testing is more expensive to set up but does not rely on the user’s subjective response. 

3. Know the limitations and advantages of each fit test method. 

4. Understand the conditions at the workplace where respirators are required.

For example, quantitative testing is recommended by NIOSH when facepiece leakage must be minimized for work in highly toxic atmospheres or those immediately dangerous to life or health.

5. Recognize the types of masks that require fit testing to work correctly.

These include: 

  • Filtering facepieces such as N95 or KN95 masks
  • Half-face respirators
  • Full-face respirators
  • SCBA’s

6. Recognize your obligations as an employer to ensure adequate personal protection equipment, including properly fitted masks, is provided to employees who need it. 

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