Respirator: Fit Checking and Fit Testing

Respirator: Fit Checking and Fit Testing

What good does a sinking boat do on the ocean? None, right? The same may be said about the respirators you'll be wearing for respiratory protection if they don't fit properly or leak.

Respiratory protection equipment (RPE) either filters the air or provides breathable air from an outside source to protect you from dust, mist, gases, and other hazardous compounds that could cause fatal lung injury. However, there are no face masks or respirators that come with a perfect fit for every user.

To guarantee that you or your employees are protected from dangerous airborne particles, OSHA and the Workers Protection Standard recommend that you should fit-test and check your respirators once a year. You'll also need to run the test if the user's face changes dramatically due to weight loss or an injury.

Since your workplace safety is heavily reliant on the performance of your respirator, ensuring how well your respirator fits and protects you against internal leaks can be a lifesaver. Thus, in today's article, we'll go over what fit checking and fit testing are, as well as all the nuances you should consider for overall respiratory protection.

Respirator fit testing

What Is Fit Testing of RPE

A fit test is a means of determining whether your respiratory protective equipment (RPE) is comfortable and capable of providing proper protection against expected airborne threats. However, only occupational hygienists, healthcare professionals, or the manufacturers of your RPE, in some instances, are qualified to perform this test.

For every tight-fitting respirator, fit testing is used to detect if there is any gap between the respirator facepiece and the user's face. If a respirator fails a fit test, the user can try a respirator of a different size or model to find a better fit. 

Also, in some cases, the user might have to opt for an alternative that doesn't rely on a tight-fitting face seal, for example, the hood type. It's worth noting that if a person needs more than one type of respirator, each one must be fit tested before practical usage. 

Fit Testing Methods

Respirator selection and use are governed by national legislation across countries. For most countries, the safety requirements for RPE fit testing can be fulfilled by two methods– qualitative and quantitative testing.

Qualitative Fit Testing (QLFT)

The qualitative fit test is subjective as it depends on the user's senses. This test is used to examine if there is a leak in negative pressure respirators and tight-fitting facepieces by exposing the worker to an odorous substance and seeing if they can smell and react to it while wearing their respirator.

Respirator fit checking

The test starts with a raw/unfiltered sampling of the substance that will be used in the actual test to see if the test participant can identify it. The most common substances include:

  • Isoamyl Acetate– This substance gives the smell of a banana. Only elastomeric respirators are fit-tested with this substance.
  • Saccharin– The fit tester uses an aerosol of an aqueous solution of Sodium saccharin to fit test both elastomeric and filtering respirators. This substance has a sweet taste. If the respirator is leaking, the test subject will perceive a sweet taste as he or she breaths via the mouth while slightly sticking out the tongue.
  • Denatonium– This substance has a bitter flavor. This compound is mixed with water and sprayed the same way as the previous ones to check if the test subject can detect it.

For this test, the test subject also has to perform the following exercises for one minute each:

  • Normal Breathing
  • Deep Breathing
  • Moving the Head: Side to Side
  • Moving the Head: Up and Down
  • Bending Over
  • Talking
  • Repeat Normal Breathing

The respirator passes the qualitative fit testing if the test subject doesn't detect any smell, taste, or irritation during these tasks. 

Quantitative Fit Testing (QNFT)

Unlike qualitative fit testing, quantitative fit testing is objective as it is measured by instruments and produces a numeric result called the "fit factor." Thus, this data-driven test is more reliable. 

This test, too, uses a test substance (also known as a control agent) like the previous one. However, the concentration of the substance within or outside the respirator can be detected here by evaluating the airflow rate under the mask with specialized equipment.

OSHA certifies 3 quantitative fit testing protocols:

  • Generated Aerosol: It uses a non-hazardous aerosol, for example, corn oil, generated in a test chamber.
  • Condensation Nuclei Counter (CNC): It uses an ambient aerosol and doesn't require a test chamber.
  • Controlled Negative Pressure (CNP): This protocol uses a test where a vacuum is temporarily created by cutting the air off.
Quantitative Fit Testing

This test, too, requires the test subject to perform the exercises mentioned earlier. Also, the test subject has to go through an additional "grimace" test where the user has to smile or frown for at least 15 seconds.

The respirator requires a fit factor of 100 in the case of half-face respirators and a fit factor of 500, at least, for full-face negative pressure respirators to pass the test.

What Is Fit Checking of RPE

A fit checking is a quick check to determine whether a respirator fits the wearer. The user must fit check the respirator each time it is used. Remember, fit checking does not replace the need for fit testing.

Thus, before fit checking, the respirator must go through the fit testing methods mentioned above. Also, the safety professional or supervisor at the workplace should ensure that the respirator is properly positioned on the face and the seal is tight between the facepiece and the face of the user.

Tip: If fog appears in the users' safety glasses while wearing respirators, there is a leak in the respirator.

Let's have a look at some of the things you should do to ensure efficient fit checks.

Fit Checking Checklist

Before you start using your respirator, make sure it is in a good working state. The checklist below will help you get started:

  • Look for fractures, scratches, and dust on the facepiece. Check for deformed, cracked, or torn inhaling valves. You’ll have to replace any damaged parts before using them.
  • Check if the headbands are intact or not. They should have strong elasticity.
  • Check for cracks in the plastic parts and the gaskets. Also, if any of the parts don’t fit and get loosened, replace them.
  • Ensure your respirators contain at least two filters of the same type.
  • Ensure that the filter you've chosen is appropriate for the application intended.

Fit Checking Checklist

Fit Checking: Adjustments

Fit checking also ensures the efficiency of your respirator and whether or not the proper adjustment is achieved. You can perform a positive and negative pressure check on your respirator each time you fit-check it for accurate adjustments.

Positive Pressure Check

Cover the exhalation valve with your palm and breath gently. If the facepiece bulges slightly and no air leaks are detected between the face and the facepiece, there is a proper seal. If you notice an air leak in the face seal, reposition the respirator on your face and re-tighten the elastic bands to eliminate the leakage.

Negative Pressure Check

When the support is attached to the cartridge, limit airflow and cover the open region of the filter holder with your palms for a negative pressure test. Inhale gently and if you detect no leakage, the facepiece is adjusted correctly.

Respirator Fit Testing Requisites: Hygiene Protocols You Need to Follow

Before and after fit testing, test subjects and testers should take measures to reduce the risk of infection transmission and ensure basic hygiene practices are followed. You can consider taking the following risk assessment measures:

  • Make sure that the room where the fit testing will take place has appropriate ventilation.
  • Both the testers and test subjects should wash and sanitize their hands before and after fit testing the RPE.
  • For fit testing of non-disposable respirators, the test subjects themselves should disinfect the respirators using an alcohol pad or disinfectant cleaning wipe. Please follow the manufacturer's cleaning instructions to avoid damaging the mask. 
  • Use disposable gloves while cleaning tubes, hoods, and other parts of your respirator. Also, ensure proper and safe disposal of the gloves.
  • More than one person should not use test respirators that cannot be thoroughly sterilized.
  • Dispose of used gloves, cleaning wipes, and disposable respirators immediately in a trash bin.

Respirator Fit Testing Requisites

Is It Necessary to Clean Your Facial Hair while Using A Respirator?

A good seal between your face and the RPE is a must whenever your situation needs you to wear a tight-fitting respirator. There must be no gaps around the edge of your RPE's facepiece, or your lungs will fall prey to the toxic air. And, facial hair makes it almost impossible to ensure a good seal.

Therefore, it's best if you clean-shave your facial hair before using a tight-fitting respirator. However, if you must have a beard or facial hair, you can always choose other respirators that do not rely on a tight fit to the face.

For an in-depth explanation of the various types of respirators available, please see our detailed article on "Types of Respirators."

Fit Testing and Checking: Things to Remember

Hopefully, you now have a good knowledge of what fit testing and checking involves, as well as the requirements for better respiratory protection. So, before we wrap up, let's have a look at when a fit test and check is a must:

  • The first time you put on tight-fitting respirators
  • Each time you or your employees are issued with a new respirator
  • If any change occurs in the user's facial features that can alter the performance of the face seal
  • Standard RPE fit testing mandated by national legislation– once a year

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