A respirator fit test is a systematic safety procedure designed to ensure that a tight-fitting respirator forms a proper seal against the wearer’s face. This seal is necessary because even the most effective filters cannot protect against airborne hazards if contaminated air leaks around the edges of the mask. The primary goal is to confirm that the specific model, size, and brand of respirator provides the intended level of protection by minimizing contaminants that bypass the facepiece. Tight-fitting respirators, such as N95s or elastomeric half and full facepieces, must be fit tested before initial use in the workplace.
Understanding Qualitative and Quantitative Testing Methods
There are two main approaches used to verify the proper fit of a respirator: qualitative and quantitative methods. Each method achieves the same goal of verifying the seal but uses a distinct mechanism to measure effectiveness. The choice between the two often depends on the type of respirator being tested and the specific regulatory requirements for the work environment.
Qualitative Fit Testing (QLFT) is a subjective, pass/fail method that relies on the wearer’s sensory experience to detect leakage. This test introduces a harmless chemical agent into a hood placed over the wearer and the respirator. If the wearer detects the agent’s taste, smell, or experiences an involuntary reaction, it signifies a leak and a test failure. Common agents include saccharin (sweet taste) or Bitrex (bitter taste).
Quantitative Fit Testing (QNFT) is an objective method that uses specialized instruments to numerically measure the amount of leakage. Machines like a Portacount measure the concentration of microscopic particles both inside and outside the respirator. The resulting ratio of outside-to-inside particle concentration is called the “fit factor.” This method provides a specific, measurable result, typically requiring a minimum fit factor of 100 for a half-mask respirator to pass. Since qualitative testing is the more common method, the practical steps that follow focus on that procedure.
Essential Preparation Before Testing
Before any fit test can begin, the individual must meet several preliminary requirements. A medical evaluation is the first step, where a licensed healthcare professional confirms the wearer is physically able to safely use a respirator. This evaluation typically involves a questionnaire that screens for conditions, such as heart or lung issues, that could be exacerbated by the resistance to breathing the respirator creates.
Proper respirator selection is a mandatory prerequisite, as the test must be performed on the exact make, model, and size the individual will use on the job. The facepiece must be correctly chosen based on the type of airborne hazard and the required level of protection. Furthermore, the wearer must not eat, chew gum, or drink anything other than water for a minimum of 15 to 30 minutes prior to the test.
The integrity of the face seal is paramount, necessitating a clean-shaven face where the respirator seals against the skin. Any facial hair, such as a beard or heavy stubble, that crosses the sealing surface prevents a proper fit and results in an automatic failure. Head-worn items that might interfere with the seal, including safety glasses or hearing protection, must be worn during the test if they will be worn on the job. Immediately before the test, the wearer must perform a user seal check, such as a negative pressure check, confirming the mask is correctly donned.
Conducting the Qualitative Fit Test
The qualitative fit test procedure begins with a sensitivity check to confirm the wearer can detect the test agent. The individual wears a test hood but no respirator, and a low concentration of the test solution (saccharin or Bitrex) is sprayed into the hood. The number of sprays required for the person to taste the solution is recorded, establishing their individual threshold. If the person cannot detect the initial agent after a maximum of 30 sprays, the test must switch to the alternative agent.
Once the threshold is established and the taste has dissipated, the wearer puts on the respirator and the test proceeds. The individual is placed back under the test hood, and the tester introduces an initial dose of the full-strength test solution, corresponding to the established sensitivity threshold. The wearer must then perform a sequence of seven specific exercises, each lasting 60 seconds, designed to simulate movements made during work. Throughout the seven minutes of exercises, a “top-up” dose of half the initial spray count is introduced every 30 seconds to maintain the concentration of the test agent inside the hood. If the wearer detects the taste at any point, the test is immediately stopped, resulting in a failure.
Sequence of Exercises
- Normal breathing
- Deep breathing
- Moving the head from side to side
- Moving the head up and down
- Speaking aloud
- Bending over at the waist (or jogging in place if space is limited)
- Final minute of normal breathing
Frequency of Testing and Handling Failures
Regulatory bodies, such as the Occupational Safety and Health Administration (OSHA), require that a fit test be performed at least once every year for any individual using a tight-fitting respirator. This annual retesting is necessary because studies show that a significant percentage of people may fail a fit test after a year, even when using the same respirator. The annual requirement ensures the respirator continues to provide the necessary protection.
A new fit test must be conducted immediately if the wearer experiences any alteration to their facial structure that could affect the seal. Such changes include significant weight gain or loss, major dental work, or facial scarring in the seal area. A new test is also required any time a different make, model, or size of respirator is selected. The daily user seal check is not a substitute for the formal fit test, but it ensures the mask is donned correctly each time.
If a fit test is failed, the procedure stops, and corrective action must be taken. Initial troubleshooting includes having the wearer adjust the placement of the respirator, retighten the straps, or attempt a different size of the same model. If the user fails the test after trying multiple adjustments or a different size, they must be tested with a completely different model or brand until a successful seal is achieved.