Fit tests are either quantitative or qualitative. A quantitative fit test uses a machine to provide a numeric assessment of how well a respirator fits a particular individual by measuring the actual amount of leakage into the respirator. A qualitative fit test, on the other hand, is a non-numeric pass or fail test that relies on a respirator wearer’s response to whether or not he or she detects the presence of a test substance (e.g., irritant smoke) when wearing a particular respirator.

Full facepiece respirators and half facepiece reusable respirators need to be quantitatively fit tested when used in environments where the contaminant concentration exceeds ten times the permissible exposure limit, or the “Assigned Protection Factor” (APF) calls for a fit factor greater than 100.

Advantages of quantitative fit testing:

• No protection-factor limit
• Documentation of numerical results
• No chance of employee deception or bluffing

Disadvantages of quantitative fit testing:

• Only one employee may be fit tested at a time
• More costly than qualitative fit testing