Respirator Fit Testing

Qualitative Fit Testing (QLFT):

• Principle:

  • QLFT relies on the user's sense of taste or smell to detect leakage of a challenge agent.  

  • It's a pass/fail test, meaning it determines if the respirator provides an adequate seal, but not the exact amount of leakage.  

• Challenge Agents:

  • Saccharin (sweet): A sweet-tasting aerosol.

  • Bitrex (bitter): A bitter-tasting aerosol.  

  • Isoamyl acetate (banana oil): A strong-smelling vapor.  

  • Irritant smoke: A smoke that irritates the upper respiratory tract.  

• Procedure:

  • Preparation:

    • The employee puts on the respirator and performs a user seal check.

    • The tester explains the test procedures and the challenge agent.

    • The tester ensures the employee can detect the challenge agent.

  • Challenge:

    • The tester introduces the challenge agent into a test hood or around the respirator.

    • The employee performs a series of exercises (e.g., normal breathing, deep breathing, head movements, talking).  

    • The tester observes the employee for signs of leakage (e.g., coughing, sneezing, detecting the challenge agent).

  • Pass/Fail:

    • If the employee does not detect the challenge agent during the exercises, the test is considered a pass.  

    • If the employee detects the challenge agent, the respirator fails the test, and adjustments or a different respirator are needed.  

• Advantages:

  • Relatively inexpensive and easy to perform.

  • Requires minimal equipment.

• Disadvantages:

  • Subjective and relies on the user's senses.  

  • Less precise than quantitative fit testing.

  • Irritant smoke can be uncomfortable for some people.

Quantitative Fit Testing (QNFT):

• Principle:

  • QNFT uses instruments to measure the actual amount of leakage into the respirator.

  • It provides a numerical fit factor, which indicates the level of protection provided by the respirator.  

• Methods:

  • Controlled Negative Pressure (CNP): Creates a vacuum inside the respirator to measure leakage.  

  • Ambient Aerosol (Portacount): Measures the concentration of particles inside and outside the respirator.  

• Procedure:

  • Preparation:

    • The employee puts on the respirator and connects it to the testing instrument.

    • The tester explains the test procedures and the instrument readings.

  • Challenge:

    • The employee performs a series of exercises (e.g., normal breathing, deep breathing, head movements, talking).  

    • The instrument measures the leakage of particles or pressure changes inside the respirator.

  • Fit Factor Determination:

    • The instrument calculates a fit factor, which is the ratio of the concentration of particles outside the respirator to the concentration inside.  

    • A higher fit factor indicates better protection.

  • Pass/Fail:

    • The test is considered a pass if the fit factor meets or exceeds the required minimum for the respirator.

    • If the fit factor is below the minimum, the respirator fails the test.

• Advantages:

  • Objective and provides precise measurements.

  • More reliable than qualitative fit testing.

  • Can be used for all types of tight fitting respirators.

• Disadvantages:

  • More expensive and requires specialized equipment.

  • Requires trained personnel to operate the testing equipment.

General Fit Testing Considerations:

• Respirator Selection:

  • Ensure the respirator is appropriate for the identified hazards.

  • Provide a variety of respirator sizes and models to accommodate different facial features.

• User Seal Checks:

  • Train employees on how to perform user seal checks before each use of a respirator.

  • User seal checks are quick checks to ensure the respirator is properly positioned and sealed.  

• Frequency:

  • Fit testing is required:

    • Before the employee is initially assigned to use a respirator.

    • Annually.

    • Whenever there is a change in the employee's facial features that could affect the fit (e.g., weight gain or loss, facial surgery).  

• Documentation:

  • Maintain detailed records of all fit testing, including:

    • Employee's name and date of birth.

    • Date of the fit test.

    • Type of respirator and size.

    • Type of fit test (qualitative or quantitative).

    • Challenge agent (if applicable).

    • Fit factor (if applicable).

    • Name of the tester.

    • Pass/fail result.

• Environmental conditions:

  • The area for the test should be free of anything that could affect the test.

• Facial Hair:

  • Facial hair that interferes with the respirator seal is not permitted.

Why Seal Checks Are Important:

• Respirators rely on a tight seal against your face to prevent contaminated air from leaking in.

• Facial hair, changes in facial features, or improper placement can compromise the seal.

• Seal checks verify that the respirator is working as intended.

Types of Seal Checks:

• Negative Pressure Seal Check:

  • This check simulates inhalation.

  • It's used for tight-fitting respirators with filters or cartridges.

• Positive Pressure Seal Check:

  • This check simulates exhalation.

  • It's used for tight-fitting respirators with exhalation valves.

How to Perform a Negative Pressure Seal Check:

1. Don Your Respirator:

   • Put on your respirator according to the manufacturer's instructions.

   • Ensure it's properly positioned on your face.

2. Cover the Inhalation Port(s):

   • For respirators with filters or cartridges, gently cover the filter or cartridge inlets with your palms or hands.

3. Inhale Gently:

   • Inhale gently, and hold your breath for about 10 seconds.

4. Check for Leakage:

   • If the respirator collapses slightly, and you don't feel any air leaking around the edges, the seal is likely good.

   • If you feel air leaking, readjust the respirator and repeat the check.

5. Repeat as Needed:

   • If you still have a leak, you may need to try a different size or type of respirator.

How to Perform a Positive Pressure Seal Check:

1. Don Your Respirator:

   • Put on your respirator according to the manufacturer's instructions.

   • Ensure it's properly positioned on your face.

2. Cover the Exhalation Valve:

   • Gently cover the exhalation valve with your hand.

3. Exhale Gently:

   • Exhale gently, and hold your breath for about 10 seconds.

4. Check for Leakage:

   • If you feel a slight positive pressure inside the respirator, and no air leaking around the edges, the seal is likely good.

   • If you feel air leaking, readjust the respirator and repeat the check.

5. Repeat as Needed:

   • If you still have a leak, you may need to try a different size or type of respirator.

Important Considerations:

• Follow Manufacturer's Instructions: Always refer to the manufacturer's instructions for your specific respirator model.

• Perform Checks Regularly: Conduct seal checks every time you put on your respirator.

• Facial Hair: Facial hair can prevent a proper seal. Shaving is typically required for effective respirator use.

• Fit Testing: Seal checks are not a substitute for a formal fit test, which is required by OSHA regulations. A fit test is performed by a qualified professional to determine the appropriate respirator size and type for your face.

• Report Problems: If you consistently have difficulty achieving a good seal, report the problem to your supervisor.