Qualitative Fit Testing
Qualitative fit testing is a pass/fail method used on half-masks that relies on senses – such as taste and smell – to detect air leakage from your respirator. The half masks being tested much have an overall fit factor (mask particle concentration divided by the ambient particle concentration) of 100 or less. The test relies on a harmless, yet bitter-tasting chemicals called Bitrex, which will determine whether you pass. Rather than measuring the amount of leakage into the facepiece, the qualitative fit test determines whether the facepiece is in working order. Unfortunately, if you taste a bitter substance, it is a failure.
The following mandatory qualitative fit test protocols (OSHA) are recognized test agents:
- Isoamyl Acetate (Isopentyl Acetate or Banana Oil) – This qualitative fit test agent uses a person’s response to fruit-like banana aroma to detect leakage into the respirator. A drawback to this agent is lack of a strong reaction in some fit test subjects to the banana odor. Another drawback is it can only be used with respirators equipped with organic vapor cartridges.
- Saccharin Solution – This qualitative fit test agent uses a person’s response to a sweet taste to detect leakage into the respirator. The drawback to this agent is lack of a strong reaction in some test subjects to a sweet taste.
- Bitrix™ (Denatonium Benzoate) – This qualitative fit test agent uses a person’s response to a bitter taste to detect leakage into the respirator. The advantage this agent has over Isoamyl Acetate and Saccharin is the bitter taste. Few enjoy a strong bitter taste so an unavoidable response by the test subject is readily noticed.
- Irritant Smoke (Stannic Chloride) – This qualitative fit test agent uses a person’s response to the irritating chemicals released in the “smoke” produced by a stannic chloride smoke tube to detect leakage into the respirator. The stannic chloride reacts with humidity producing a white smoke with a pungent odor. The drawback to Irritant smoke is that it can be toxic. The smoke contains two compounds: hydrogen chloride (HCl) and tin (Sn). Hydrogen chloride is highly corrosive to human tissue. Inhalation of a relatively low concentration will cause irritation to the upper respiratory tract and eyes. Therefore, it’s such an effective chemical to use for respiratory fit testing.
Before beginning qualitative fit testing protocol, employees are given a description of the fit test and their responsibilities during the procedure. All four qualitative fit test protocols use these seven, 60-second exercises:
- Normal breathing: – standing position without talking.
- Deep breathing – standing position without talking, breathing slowly and deeply.
- Turning head side-to-side – standing position, slowly turning head side-to side, holding at extreme point and inhaling.
- Moving head up and down – standing position, slowly moving head up and down and inhaling in the up position.
- Talking – talk out loud slowly and loud enough to be heard clearly; read from a prepared text count backward from 100 or recite a memorized poem.
- Bending over/jogging in place – bend at the waist as if to touch toes. Jogging in place is substituted for testing done in a shroud that does not permit bending over at the waist.
- Normal breathing – standing position without talking.
Even though these qualitative fit testing agents can be used to fit test both half-mask and full-face respirators, it is important to note that qualitative fit tests only validate an assigned protection (APF) of 10. OSHA has established an APF of 50 for full facepiece respirators, but in order to use a full facepiece beyond 10 times the permissible exposure limit (PEL), a quantitative fit test must be performed.
