Why fit test a respirator? Getting a good fit with a respirator is essential to protect employees against respiratory hazards. If the facepiece doesn't fit tightly on the employee's face, the employee could be exposed to the very hazards the respirator is designed to protect against. Because a good fit is so important, fit testing is required in OSHA's respiratory protection standard (29 CFR 1910.134[f]). The regulations specify two kinds of fit tests:

• Qualitative fit tests rely on the employee's senses of smell and taste to determine if the respirator fits tightly. If the employee doesn't smell or taste the test agent (bitrex, saccharin, isoamyl acetate, or irritant smoke) during the test, then the fit is good.
• Quantitative fit tests use instruments to measure face seal leakage.

Which test you have to use depends on employee exposure levels to hazardous air contaminants. For negative-pressure air-purifying respirators, you can use either a qualitative or a quantitative fit test for exposure levels of less than 10 times the occupational exposure limit.

When exposure levels are greater than 10 times the occupational exposure limit, you have to use a quantitative fit test. Fit testing of atmosphere-supplying respirators and powered air-purifying respirators can be performed with either a quantitative or qualitative fit test. (NOTE: The employee must be tested with the same make, model, style, and size of respirator that will be used on the job.)

When do you have to conduct a fit test? OSHA requires a fit test when the employee is initially assigned a job that requires the use of a respirator. Then you have to conduct another fit test every year to make sure that the facepiece seal is still tight and safe. A new fit test is also required whenever an employee:

• Uses a different kind of respirator (size, style, model, or make)
• Undergoes physical changes that could affect respirator fit, such as dental changes, facial scarring, cosmetic surgery, or weight loss that affects the face
• Reports a problem with respirator fit

How's it done? Mandatory fit test procedures are outlined in detail in Appendix A of 1910.134. In some cases, manufacturers are willing to do the first fit test free or for a small fee. Thereafter, you either have to have qualified personnel in-house to perform the tests or hire a contractor to do them for you. During the test the employee will be asked to help the tester assess whether the respirator is the proper size and whether the fit is comfortable in terms of such criteria as:

• Position of the mask on the nose and across the nose bridge
• Position of the mask on the face and cheeks
• Placement of the chin
• Tendency of respirator to slip
• Adequate strap tension (but not too tight)
• Room for eye protection
• Room to talk

Employees will also be asked to perform some test exercises, including normal breathing, deep breathing, turning the head from side to side and moving it up and down, talking, and bending over. Each exercise is performed for a minute. The tester will ask the employee about the comfort of the respirator following each exercise. If the comfort level is unacceptable, another model of respirator must be tried. Any employees who experience difficulty breathing during the test must be referred to a physician to determine whether they can be medically cleared to wear a respirator.

What's the difference between fit testing and seal checking? Although a seal check is part of the fit test procedure, it's really a separate procedure that should be performed by employees every time they put on a respirator, not just once a year. The seal check makes sure the facepiece is properly positioned on the face and the seal is tight. Mandatory seal check procedures are explained in detail in Appendix B-1 of 1910.134. Seal checking involves using a positive and/or negative pressure check (or the manufacturer's recommended seal check method).

• To conduct a positive pressure check, the employee closes off the exhalation valve and exhales gently into the facepiece. The fit is considered satisfactory if a slight positive pressure can be built up inside the facepiece without any outward leakage of air at the seal.
• To conduct a negative pressure check, the employee closes off the inlet opening of the canister or cartridge(s) by covering with the palm of the hand(s) or by replacing the filter seal(s). Then the employee gently inhales and holds the breath for 10 seconds so that the facepiece collapses slightly. If the facepiece remains in a slightly collapsed state and there's no inward leakage of air, the tightness of the respirator is considered satisfactory.