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The Importance of a Proper Fit: How to Conduct a Respirator Fit Test

By Rick Pedley, Contributor

Fit tests are crucial to any respiratory protection program, identifying gaps and leaks that put workers at risk.

Different work environments can expose workers to a variety of respiratory hazards, including dust, fumes, gases, and volatile organic compounds (VOCs). While respirators offer excellent protection against these contaminants, even the most advanced safety equipment is ineffective if it doesn’t fit the user properly. This makes respirator fit testing an essential aspect of respiratory protection programs.

What is a Respirator Fit Test?

The Occupational Safety and Health Administration’s (OSHA) Respiratory Protection Standard outlines requirements for protecting workers from respiratory hazards in various industries. In addition to providing face masks and respirators to employees, the guidelines require employers to train workers on respiratory safety, including how to put on a respirator and how to determine optimal fit.

A respirator fit test is a protocol used to evaluate whether a specific respirator model fits an individual worker properly. The goal is to ensure the personal protective equipment (PPE) creates a secure seal around the user’s face, preventing contaminants from bypassing the mask. Fit tests are crucial to any respiratory protection program, identifying gaps and leaks that can put workers at risk.

Users must conduct a fit test before wearing a mandatory respirator for the first time. Subsequently, users must perform fit tests annually and when significant weight changes or dental work affects the fit of protective equipment.

Types of Respirator Fit Tests

There are two main types of fit tests:

  • Qualitative Fit Test: This subjective test is based on the user’s sense of taste, smell, or irritation. Here, the user wears the respirator inside a test hood as the tester sprays one of four OSHA-accepted test agents into the hood (Isoamyl acetate, Saccharin, Bitrex®, or irritant smoke). The test is either pass or fail, depending on whether the individual can detect the substance.
  • Quantitative Fit Test: This test measures the actual fit factor using specialized equipment, such as particulate counters or ambient aerosol generators, to provide a numerical value indicating the level of protection provided by the respirator. Fit tests require a fit factor of at least 100 for half-mask respirators and a minimum score of 500 for full-face, negative-pressure respirators.

Both tests require the user to perform a series of exercises simulating regular work movements for one minute each. These include normal breathing, deep breathing, turning the head to the side, moving the head up and down, talking, bending over, and returning to normal breathing. Quantitative fit tests add a “grimace test” where the subject smiles or frowns for 15 seconds.

How to Conduct a Respirator Fit Test

Conducting a respirator fit test involves a comprehensive process to ensure workers have safe and effective fitting protective equipment. Here’s a general outline of the fit test procedure:

  1. Pre-Test Preparation

The subject must complete the required OSHA medical evaluation questionnaire to ensure the user has no underlying conditions that might hinder the test.[1] In addition, workers must remove facial hair or any type of apparel interfering with the respirator seal before testing.

Once the test subject passes the medical evaluation, subjects will be shown the basics of properly wearing a respirator, including:

  • How to put on a respirator
  • How subjects should position it on the face
  • How to set strap tension
  • How to determine an acceptable fit

Following this, workers can choose the most appropriate respirator based on the type of work and hazards present while assessing the fit and comfort of each respirator model and size. This includes a seal check, where the subject covers the respirator’s inlet and exhalation valves, performing breathing exercises to confirm that it has a secure fit.

  1. Sensitivity Test

This determines the subject’s sensitivity to the test solution used in qualitative fit testing. Here are the steps:

  • Add one teaspoon of the test solution (Bitrex® or Saccharin) into the reservoir at the top of the nebulizer bulb.
  • Squeeze the bulb several times to confirm the device is creating a mist.
  • Verify that the participant has not eaten, smoked, or chewed gum within 15 minutes of the test, as this can affect sensitivity. If they have, wait 15 minutes before beginning the test.
  • Without a respirator on, place the hood and collar over the subject’s head. Ask the subject to breathe through the mouth with the tongue slightly out. Have them indicate when they taste the solution by raising their hand.
  • Place the nebulizer bulb through the hole in the front of the hood. Squeeze the bulb and let it fully inflate before squeezing again. The number of squeezes it takes for the employee to detect the taste establishes their sensitivity level.

When conducting the fit test with the respirator, use the same number of repetitions before deciding whether the seal is sufficient.

  1. Fit Test

Before conducting the test, ask the test subject to put on the respirator and other PPE required for their job (safety glasses, hearing protection, hard hats, etc.). This allows you to simulate actual work conditions.

For qualitative tests: 

  • Place the hood over the subject’s head and introduce the test substance. Ask the subject to perform a series of exercises, such as moving the head side to side, nodding up and down, and talking, while checking if they detect the test substance.
  • The subject passes the test when they complete all of these tasks without tasting the mist. If the subject tastes the solution at any time, you must re-administer the entire fit test.

For quantitative tests:

  • Connect the respirator to the testing device. The machine will measure the air inside and outside the respirator as the test subject performs the prescribed series of exercises.

After the test, document the results, recording details including respirator make, model, size, test type, and other relevant test subject information.

Use a Reliable Respirator Fit Test Kit

Using a quality respirator fit test kit from reliable manufacturers is critical to ensuring worker safety. To cite an example, the Allegro Bitrex Respirator Fit Test Kit 2041 is a popular choice for employers across a range of industries.[2] The solution comes in disposable glass ampules, making it easier to pour the solution into the nebulizers while reducing the chances of contamination.

For more information about respirator fit tests and respiratory protection programs, consult a workplace safety expert or visit the OSHA website.

Rick Pedley is the President and CEO, PK Safety (



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