Fit testing kit - guide

The fit test works like this:

  1. Put on your mask.
  2. Stick your tongue out a bit and breathe through your mouth.
  3. Pretend you're doing things you'd normally be doing when wearing your mask.
  4. If you taste bitter, there's a leak!

There's more to it than that so read on, but that's the basic idea.

Table of Contents

Opening the kit

Assembling the fit test hood

When you take the fit testing hood out of the box it will look something like this:

Fold the top flaps together to form a box shape. Like so:

Performing a mask fit test

Before you begin

Make sure your face is clean shaven if you have facial hair. Your mask will not fit you as well if you have any facial hair (even stubble), so you will likely fail the fit test unless you are clean shaven.

Don't eat / drink anything (besides water), smoke or chew gum for about 15 minutes before the test. If you normally wear glasses, wear glasses during the test.

For best results, you will need some distilled water or distilled white vinegar. This isn't a strict requirement but it will help your nebulizer last longer. Distilled water or distilled white vinegar can be found at almost all grocery stores. You will only need a little bit of it.

Setup: the hood

First you'll want to assemble the fit testing hood, as described earlier.

Then you'll want to place it over your head, with the sides resting on your shoulders. Like this:

Try to adjust the position of the hood so there aren't major gaps between your body and the hood. If you notice a large gap in the front of the hood, try moving the hood forward so more of it lays on your chest. You can also bend the flaps (that say "bend to fit as needed") on the side to better fit your body.

The hood doesn't need to be air tight. If you have long / large-volumed hair you will want to pull it back if possible. If you have a jacket / hoodie on, you'll want to take that off.

Setup: the nebulizer

To turn on the nebulizer, press the circular button on the front of the device. To turn it off, press the button again. When performing tests you will be pressing the button (on) then pressing it again (off) after a half-second.

Sensitivity test

First let's figure out how sensitive you are to the bitter! We use this information to decide how much to spray into the air.

For this test you will not be wearing a mask.

It's best to have someone else holding the nebulizer and doing the test on you. If you have no one to help you can do this test on yourself.
  1. Pour a small amount of the sensitivity solution into the nebulizer. Don't pour the whole bottle in! You just need a little bit. The sensitivity solution is in this bottle:

  1. Put the hood over your head, as described above. You should not be wearing a mask for this test.

  2. With your tongue sticking slightly out, breathe through your slightly open mouth.

  3. Hold the nebulizer a few inches away from the hole in the center of the hood. Do not hold the nebulizer directly up against the hole:

Then point the circular metal part of the nebulizer toward the hole in the hood. We want the spray that it makes to go through the hole in the hood.

  1. Turn your head to the side, so your mouth/nose/eyes aren't directly facing the hole in the hood.

  2. Very quickly turn on the nebulizer for a half-second and then turn it off. Just a quick burst!

  3. Remember to breathe through your slightly open mouth with your tongue sticking out a little bit during the test. Do you taste the bitter? Wait up to 10 seconds to see if you can taste it.

    If you tasted it, you're done with sensitivity test! It took you one spray to taste the bitter.

  4. If you didn't taste it and 10 seconds went by, turn your head to the side again and then do another very quick half-second spray — a very quick burst.

  5. Do you taste the bitter? Wait up to 10 seconds to see if you can taste it.

    If you tasted it, you're done with sensitivity test! It took you two sprays to taste the bitter.

  6. If you didn't taste it and 10 seconds went by, turn your head to the side again and then do another very quick half-second spray — a very quick burst.

    If you tasted it, you're done with sensitivity test! It took you three sprays to taste the bitter.

    If you still can't taste the bitter then something may be wrong with your testing setup or you may be one of the very rare individuals who's insensitive to the bitter taste. See our troubleshooting guide.

Here's a video demo of the sensitivity test:

In this test, only one quick spray of was needed to taste the bitter.

Ick!! The bitter tastes awful! Yes it does! You can have one of the included hard chocolate candies:

This will help get the nasty bitter taste out of your mouth!

Cleaning up after the sensitivity test

You do the sensitivity test the first time you test yourself or someone else. You don't need to do the sensitivity test each time you test a new mask.

Mask fit test

Make sure you don't have lingering bitter taste in your mouth from the sensitivity test or previous fit tests. Make sure you haven't eaten or had anything flavored to drink in the past ~15 minutes.

First, put the mask you'd like to test on! We want to test the mask as you'd actually be wearing it, so it's best to leave the mask on for about 5 minutes before beginning the test.

It's best to have someone else holding the nebulizer and doing the test on you. If you have no one to help you can do this test on yourself.
  1. Pour a small amount of the bitter solution into the nebulizer. Don't pour the whole bottle in! You just need a little bit. The bitter solution is in this bottle:

  1. Put the hood over your head, as described above.

  2. With your tongue sticking slightly out, breathe through your slightly open mouth.

  3. Hold the nebulizer a few inches away from the hole in the center of the hood. Do not hold the nebulizer directly up against the hole:

Then point the circular metal part of the nebulizer toward the hole in the hood. We want the spray that it makes to go through the hole in the hood.

  1. Turn your head to the side, so your mouth/nose/eyes aren't directly facing the hole in the hood.

  2. Very quickly turn on the nebulizer for a half-second and then turn it off. Just a quick burst! If you needed two sprays to taste the bitter in the sensitivity test, instead use two very quick sprays, one after the other. If you needed three sprays to taste it, use three very quick sprays, one after the other.

  3. After the quick spray is done, return your head to a stationary position facing the front of the testing hood.

  4. If at any time you taste the bitter, stop the test — your mask has failed the fit test.

  5. Continue breathing through your slightly open mouth, tongue sticking slightly out. After 30 seconds, turn your head to the side again and do one more quick spray of the nebulizer. If you needed two sprays to taste the bitter in the sensitivity test then do two very quick sprays. If you needed three sprays to taste the bitter in the sensitivity test then do two (yes two) very quick sprays.

    Then turn your head back to a stationary position when the spraying is done.

  6. Wait 30 seconds in this stationary position, breathing through your slightly open mouth with tongue slightly extended.

If you tasted the bitter at any point during the one minute test then stop — your mask has failed the fit test.

Here's a video demo of the first 30 seconds of the fit test. After this, this 30 second portion is repeated:

Next we test different head positions and movements. In each of these positions, repeat steps above, except instead of keeping your head in a stationary position we do something else.

Here's the positions:

When performing each of these position steps turn your head away from the front of the hood during the spray step. Then return your head to whatever position it should be in after the spraying is done. For instance, during the talking position step, turn your head to the side while talking, spray the nebulizer, then return your head back to the regular position and continue talking.

Normal breathing

We just did this above.

Deep breathing

Breathe in and out deeply, forcing lots of air in and out of the mask.

Here's a video demo of the first 30 seconds of the deep breathing test. After this, this 30 second portion is repeated:

Head side to side

Repeatedly turn your head side to side, facing your shoulders. When turning your head, keep it in the turned position for a few seconds to make sure you're breathing in enough to test the mask.

Here's a video demo of the first 30 seconds of the head side to side test. After this, this 30 second portion is repeated:

Head up and down

Repeatedly turn your head so you're facing up, like you're looking at the sky. Then turn your head so you're facing downward, toward your chest. Keep your head in the turned positions for a few seconds each time to make sure you're testing the mask in the position for long enough.

Here's a video demo of the first 30 seconds of the head up and down test. After this, this 30 second portion is repeated:

Talking

While trying your best to kinda keep your mouth slightly open with your tongue exposed, talk! The included "Rainbow passage" sheet is useful for this step.

Read from the passage as you do this talking step. You may need to read the passage more than once during the full 1 minute test.

Here's a video demo of the first 30 seconds of the talking test. After this, this 30 second portion is repeated:

Bending over / jogging in place

Jog slightly in place, bouncing up and down during the test. Alternatively, if you can do so without the fit testing hood falling off of you, lean your torso forward so you're bending over, like you're trying to touch your toes while standing up.

Here's a video demo of the first 30 seconds of the jogging in place test. After this, this 30 second portion is repeated:

Extra positions

Add any extra positions you think would be useful for you. For instance, if you sing in a choir while wearing your mask, adding a step where you sing would be useful.

Normal breathing

Repeat the first step where you're stationary and breathing normally.

Finishing the test

If you completed each of the ~one minute position steps and didn't taste bitter then your mask passed the fit test! If at any time you tasted bitter then your mask failed the fit test.

You can log your results on the included test results sheet:

If you tasted bitter at any point during the fit test, you failed the test.

Failing the fit test means you can't assume you are getting 1% or less leakage in your mask fit; you can't assume 99% of the air you're breathing is passing through the mask.

If you did not taste bitter at any point during the fit test, you passed the test.

Passing the fit test means you're very likely getting around 1% or less leakage in your mask fit — that 99% or more of the air coming into the mask is passing through the mask rather than leaking around the sides of the mask.

If you tasted any bitter during the test (failed test) or after (lingering in air):

If you're out of our included candies, a piece of chocolate or hard candy usually works.

Cleaning up after fit testing

Gently brush the circular metal part of the nebulizer with a cotton cleaning swab. Do this after running distilled water through the nebulizer.

Challenge mode

We call the regular mask fit test the "classic fit test." Beyond the classic fit test, there is another kind of test you can perform that we call "challenge mode."

This test is optional; when people talk about "passing a fit test," they are referring to the classic fit test described above.

Only use the challenge mode test on masks you've already passed a classic fit test in.

The challenge mode test can help you pick out, from masks you've already passed classic fit tests in, masks that fit you even better. To perform the challenge mode test:

  1. The challenge mode test is just like the classic mask fit test, except we change the amount of time we spray the nebulizer for. For the challenge mode test, we use a single 10 second spray when starting a fit test exercise followed by a single 5 second spray at 30 seconds.
  2. It doesn't matter how many half-second sprays you used during the classic fit test: for the challenge mode test, use a 10 second spray at the beginning of each exercise, then a 5 second spray after 30 seconds have passed.
  3. Make sure to turn your head away while the nebulizer is being sprayed.

Here's a video explaining the challenge mode test:

If you taste bitter at any point during challenge mode, you have failed challenge mode.

Failing challenge mode means you detected a small, possibly less than 1% leak in your mask fit. Failing challenge mode on a mask does not mean the mask has "failed a fit test" in the traditional sense.

Failing a challenge mode test means that the mask does not provide as good a fit as masks that pass challenge mode.

If you did not taste bitter at any point during challenge mode, you have passed challenge mode.

Passing challenge mode means that the mask provides a better fit than masks that fail challenge mode.

Cleaning up after challenge mode

Cleaning up is the same as for the classic fit test.

Using a garbage bag as a fit testing hood

Included with the kit is an extra large, semi-see-through garbage bag with a drawstring. With care, this can be used as an alternative fit testing hood.

We recommend only using the garbage bag as a fit testing hood if you have someone to supervise you during the test. If you don't have someone to supervise you, do not perform this test.

To use the garbage bag method:

  1. Ensure you have someone to supervise you during this test. If you live alone, consider having a friend help you while wearing a well-fitting N95 mask — the fit test can be performed outside.
  2. Place the garbage bag over your shoulders — not around your neck / around your head! Work the garbage bag down until it's past your shoulders and pull in the drawstring a little bit. Do not tighten the drawstring so much you cut off air supply - maintain a large opening at the bottom of the bag, but use the draw string to cinch up the bag a little bit.
  3. Put one of your hands inside of the garbage bag. Hold the nebulizer in this hand. Point the nebulizer away from you, pointed toward the inside of the bag. Hold the nebulizer down toward the bottom of the bag. Like this:

  1. Perform the regular sensitivity testing or fit testing steps described above. For this method you do not need to turn your head away when spraying the nebulizer.

Frequent Questions & Troubleshooting

I fail the classic mask fit test in every mask I tested, what should I do?

The first thing to do is to make sure you are following the steps as outlined above. I.e. are you completely clean shaven if you have facial hair?

The next thing to do is to try and find different masks that may fit you better. One type of N95 you may want to try is the 3M Aura style N95 because a high % of people pass fit tests in this kind of N95.

You can also try and figure out where and how you are failing the fit test. For instance, you may be able to figure out that you're failing because your mask is leaking under your chin or around your nose. How can you figure this out? One way is to hold the mask really tightly to your face while doing an abbreviated fit test and see if you pass it.

E.g. if you hold the mask really tight against your chin and pass, but you fail when you don't do that then you've identified where the leak is happening. You can use this information to try and find a mask that might fit you better. E.g. if you're failing under the chin you may need a mask that's shorter, vertically.

If you still cannot pass a fit test on any of the masks you test or any masks you find, you may want to look into alternatives to masks such as Powered Air Purifying Respirators (PAPR), though they are extremely expensive, loud and industrial looking.

I can't taste the bitter during the sensitivity test

We will be offering an alternative type of testing solution (saccharine) in the future for this situation.

Miscellaneous tips

Where is the link to the fit test kit store?

The fit test kit store can be found at fittests4all.bigcartel.com.