Approvals: 1st Level 2nd Level 3rd Level 

National Institute for Occupational Safety and Health 

National Personal Protective Technology Laboratory 

P.O. Box 18070 

Pittsburgh, PA 15236 

Procedure No. RCT-APR-STP-0067 Revision: 1.1 Date: 31 August 2005

PARTICULATE RESPIRATOR QUALITATIVE FIT TEST 

UTILIZING SACCHARIN OR BITREX SOLUTIONS 

1. PURPOSE

1.1 This test establishes the standard procedure for ensuring that the particulate respirators 

submitted for Approval, Extension of Approval, or examined during Approval Product 

audits meet fit test requirements established by policy and set forth in 42 CFR Part 84. 

Specifically for this test, the fitting ability of respirators may be determined for 

respirators which can not be tested using the isoamyl acetate fit test. Either Saccharin or 

Bitrex may be used. There is essentially no performance difference. 

2. GENERAL

2.1 This STP describes the Saccharin and Bitrex Fit Test in sufficient detail that a person 

knowledgeable in the appropriate technical field can select proper equipment, conduct the 

test, and determine whether or not the product passes the test. A Bitrex is a Denatonium 

benzoate solution. Bitrex is routinely used as a taste aversion agent in household liquids 

which children should not be drinking and is endorsed by the American Medical 

Association, the National Safety Council, and the American Association of Poison 

Control Centers. 

3. EQUIPMENT/MATERIAL

3.1 An enclosure that can be worn about the head and shoulders that is approximately 12 

inches in diameter by 14 inches tall with at least the front portion clear and that allows 

free movements of the head when a respirator is worn. An enclosure substantially similar 

to the 3M hood assembly, parts # FT 14 and # FT 15 combined, is adequate. The test 

enclosure shall have a 3/4-inch (1.9 cm) hole in front of the test subject's nose and mouth 

area to accommodate a nebulizer nozzle. 

3.2 Two DeVilbiss Model 40 Inhalation Medication Nebulizers or equivalent 

3.3 One container of Saccharin or Bitrex 

3.4 One container (8 oz. or more) of Salt (Nacl) when Bitrex is used

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3.5 One quart (or more)- odor-free water (e.g., distilled or spring water) at 

approximately 25 deg. C (77 deg. F) for the solutions. 

4 TEST PANEL

4.1 Test panel size selection: Particulate respirators are typically offered in sizes. Where 

respirators submitted by the manufacturer are offered in sizes, respirator panel members 

shall be selected following the Los Alamos sizing method as follows: 

4.1.1 Multiple facepiece sizes: 

Small- panel face sizes 1, 2, 3, 4; Number of panel members: 6 (1 or 2 for ea. 

size to total 6) 

Medium- panel face sizes 3, 4, 5, 6, 7, 8; Number of panel members: 6 (1 for ea. 

size to total 6) 

Large- panel face sizes 7, 8, 9, 10; Number of panel members: 6 (1 or 2 for ea. 

size to total 6) 

Small/medium- panel face sizes 1, 2, 3, 4, 5, 6; Number of panel members: 6 

(1for ea. size to total 6) 

Medium/large- face sizes- 5, 6, 7, 8, 9, 10; Number of panel members: 6 (1 for 

ea. size to total 6) 

Extra large- face sizes 8, 9, 10; Number of panel members: 6 (2 for ea. size to 

total 6) 

4.1.2 One-size-fits-all: Where respirators submitted by the manufacturer are of a 

single size facepiece where the single size is intended to fit everyone, the size of 

the test panel shall be 10 (1 for each size to total 10) 

4.1.3 Hoods/ Helmets: The same face size criteria that are used for facepieces apply 

to hoods and helmets. Reasoning is that head size is generally proportional with 

face size. 

 

4.1.4 Mouth Bit: When performing this test with a mouth bit respirator the test subject 

will not be able to stick his/her tongue out. However, this will not affect the 

ability to detect the saccharin or Bitrex because nose clips must be worn and all 

air will be inhaled through the wearer’s mouth. 

5. SOLUTION AEROSOL SCREENING 

 

5.1 The taste threshold screening is performed without wearing a respirator. It is intended to 

determine whether the test subject can detect the taste of saccharin or Bitrex. 

 

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5.2 The test subject shall don the test enclosure. Throughout the threshold screening test, the 

test subject shall breathe with his/her mouth slightly open and with the tongue partially 

extended (except mouth bit respirators). The subject is instructed to report when he/she 

detects a sweet taste. 

5.3 Using a DeVilbiss Model 40 Inhalation Medication Nebulizer or equivalent, the test 

conductor shall spray the threshold check solution into the enclosure by inserting the 

nebulizer into the hole in the front of the enclosure. The nozzle is directed away from the 

nose and mouth of the person. This nebulizer shall be clearly marked with words similar 

to “Saccharin Threshold Solution” or “Bitrex Threshold Solution” to distinguish it from 

the fit test solution nebulizer. 

5.4 For Saccharin, the threshold check solution shall consist of dissolving 0.83 gram of 

sodium saccharin USP in 100 ml of warm odor free water. It can also be prepared by 

putting 1 ml of the fit test solution (described below) in 100 ml of distilled water. 

5.5 For Bitrex, the threshold screening solution is prepared by adding 13.5 milligrams of 

Bitrex to 100 ml of 5% salt (NaCl) solution in distilled water. 

5.6 To produce the aerosol, the nebulizer bulb is firmly squeezed so that it collapses 

completely, then released and allowed to fully expand. 

5.7 Ten squeezes are repeated rapidly and then the test subject is asked whether the solution 

can be tasted. If the test subject reports tasting the sweet taste (saccharin) or bitter taste 

(Bitrex) during the ten squeezes, the screening test is completed. The taste threshold is 

noted as ten regardless of the number of squeezes actually completed. 

5.8 If the first response is negative, ten more squeezes are repeated rapidly and the test 

subject is again asked whether the solution is tasted. If the test subject reports tasting the 

solution during the second ten squeezes, the screening test is completed. The taste 

threshold is noted as twenty regardless of the number of squeezes actually completed. 

5.9 If the second response is negative, ten more squeezes are repeated rapidly and the test 

subject is again asked whether the solution is tasted. If the test subject reports tasting the 

solution during the third set of ten squeezes, the screening test is completed. The taste 

threshold is noted as thirty regardless of the number of squeezes actually completed. 

5.10 The test conductor shall note the number of squeezes required to solicit a taste response. 

5.11 If the solution is not tasted after 30 squeezes, the test subject is considered as unable to 

taste saccharin or Bitrex and may not perform this fit test. 

Note: If the test subject eats or drinks anything other than water before the screening test, 

he/she may be unable to taste the weak solutions. 

5.12 If a taste response is elicited, the test subject shall be asked to take note of the taste for 

reference in the fit test. 

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5.13 Correct use of the nebulizer means that approximately 1 ml of solution is used at a time 

in the nebulizer body. 

5.14 The nebulizer shall be thoroughly rinsed in water and shaken dry following testing. It 

shall be refilled no more that 4 hours prior to testing. 

6. SOLUTION QUALITATIVE TEST PROCEDURES: 

6.1 The test subject may not eat, drink (except plain water), smoke, or chew gum for 15 

minutes before the test. 

6.2 The fit test uses the enclosure described above. 

6.3 The test subject shall don the enclosure while wearing the respirator. 

6.4 The second DeVilbiss Model 40 Inhalation Medication Nebulizer or equivalent shall be 

used to spray the fit test solution into the enclosure. This nebulizer shall be clearly 

marked with wording similar to “Saccharin Testing Solution” or “Bitrex Testing 

Solution” to distinguish it from the screening test solution nebulizer. 

6.5 For Saccharin, the fit test solution is prepared by adding 83 grams of sodium saccharin 

to 100 ml of warm odor free water. 

6.6 For Bitrex, the fit test solution is prepared by adding 337.5 mg of Bitrex to 200 ml of a 

5% salt (NaCl) solution in warm water. 

6.7 As before, throughout the test, the test subject shall breathe with his/her mouth slightly 

open and with the tongue partially extended (except mouth bit respirators). 

6.8 The nebulizer is inserted into the hole in the front of the enclosure and an initial 

concentration of fit test solution is sprayed into the enclosure using the same number of 

squeezes (either 10, 20 or 30 squeezes) based on the number of squeezes required to elicit 

a taste response as noted during the screening test. A minimum of 10 squeezes is 

required. 

6.9 After generating the aerosol, the test subject shall be instructed to perform the following 

exercises. The test subject must perform the following test exercises for 1 minute each 

except for the grimace exercise which shall be performed for 15 seconds. The test subject 

shall be questioned by the test conductor regarding the comfort of the respirator upon 

completion of the protocol. If comfort has become unacceptable, this will constitute a 

failure with this subject. The respirator shall not be adjusted once the fit test exercises 

begin. Any adjustment following the start of the exercises voids the test, and the fit test 

must be repeated. 

(1) Normal breathing in a normal standing position, without talking. 

(2) Deep breathing in a normal standing position. The subject shall breathe slowly and 

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deeply, taking caution so as not to hyperventilate. 

(3) Turning head side to side. Standing in place, the subject shall slowly turn his/her head 

from side to side between the extreme positions on each side. The head shall be held at 

each extreme momentarily so the subject can inhale at each side. 

(4) Moving head up and down. Standing in place, the subject shall slowly move his/her 

head up and down. The subject shall be instructed to inhale in the up position (i.e., when 

looking toward the ceiling). 

(5) Talking. The subject shall talk out loud slowly and loud enough so as to be heard 

clearly by the test conductor. The subject can read from a prepared text such as the 

Rainbow Passage, count backward from 100, or recite a memorized poem or song. 

Rainbow Passage 

When the sunlight strikes raindrops in the air, they act like a prism and form a rainbow. 

 The rainbow is a division of white light into many beautiful colors. These take the shape 

of a long round arch, with its path high above, and its two ends apparently beyond the 

horizon. There is, according to legend, a boiling pot of gold at one end. People look, but 

no one ever finds it. When a man looks for something beyond reach, his friends say he is 

looking for the pot of gold at the end of the rainbow. 

(6) Grimace. The test subject shall grimace by smiling or frowning. 

(7) Bending over. The test subject shall bend at the waist as if he/she were to touch 

his/her toes. Jogging in place shall be substituted for this exercise in those test 

environments such as shroud type units that do not permit bending over at the waist. 

(8) Normal breathing (same as exercise 1). 

6.10 Every 30 seconds the aerosol concentration shall be replenished using one half the 

original number of squeezes used initially (e.g., 5, 10 or 15). 

6.11 The test subject shall indicate to the test conductor if at any time during the fit test the 

taste of the solution is detected. If the test subject does not report tasting the solution, the 

test is passed. 

6.12 If the taste of the solution is detected, the test with this subject is deemed a failure. 

NOTE: The nebulizers have a tendency to clog during use. Therefore, the test operator 

must make periodic checks of the nebulizer to ensure that it does not clog. If clogging is 

found at the end of the test session, the test is invalid. 

7. PASS/FAIL CRITERIA

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7.1 A full panel of sizes 1 through 10 is used to evaluate a one-size-fits-all respirator. All 

panel face sizes must be accounted for during the test. One failure where the test subject 

detects saccharin or Bitrex during the exercises will be permitted; however, an additional 

test using a different test subject of the same size must be performed with passing results. 

If two or more failures occur, the respirator fails testing. 

7.2 Whenever less than a full panel (one of each size 1 thru 10) is used to evaluate a single 

size of any multiple size facepiece, no failures will be allowed. These respirators are 

designed to fit a specific facial size range (such as small) and are expected to fit all 

subjects of that size range. For overlapping panel face sizes (size 3, 4, 7 and 8) a subject 

need only pass wearing a respirator in one or the other size. Test subjects in the 

overlapping groups need not pass the test in both sizes; however, all panel face sizes for a 

specified respirator size must be accounted for during the test as follows: 

7.3 The test subject will don the respirator and perform a user seal check (fit check) per the 

manufacturer’s User's Instructions. If the test subject cannot obtain a successful user seal 

check, he/she will not be used to perform the test. Upon obtaining a successful user seal 

check, the subject may perform the test. Up to three different test subjects of a specified 

size will have the opportunity to obtain a successful user seal check (fit check) before the 

respirator is considered to fail. The test subjects of the specified size will be observed to 

try to insure that there is no unique characteristic of all three that would create an unfair 

disadvantage for the respirator. For example, three test subjects would not be chosen who 

all have a very shallow nose bridge. 

7.4 The test subject must not detect the taste of the solution when performing the test 

exercises. If on initial spraying of the solution (before the exercises begin), the subject 

immediately tastes the solution, the subject may immediately remove the enclosure, 

adjust the respirator, perform a second user seal check (fit check), and if successful, reenter the chamber. If the subject again detects the taste of the solution, the respirator will 

considered as failing on the basis that the user seal check process is inadequate to 

determine fit or the respirator is unable to maintain a fit. 

8. RECORDS/TEST SHEETS

8.1 All test data collected will be recorded on the attached Particulate Respirator Test Sheet. 

8.2 Any videotapes and photographs of the actual test being performed, or of the tested 

equipment shall be maintained in the task (project) file as part of the permanent record. 

8.3 If the failure occurs to hardware examined under an Off-the-Shelf Audit; the hardware 

will be examined by a technician and the laboratory staff leader for cause. All equipment 

failing any portion of this test may be returned to the manufacturer applicant for 

examination. However, the hardware tested shall be held at the testing laboratory until 

authorized for release by the Branch Chief, or his designee. 

9. ATTACHMENTS

9.1 Partial list of test equipment suppliers. 

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 Allegro Industries 

 3M 

 Lab Safety and Supply Co. 

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Procedure No. RCT-APR-STP-0067 Revision: 1.1 Date: 31 August 2005 Page 8 of 9 

Particulate Respirator Test Sheet 

TN-_____________ Test Date:_______ 

 

Mfr. ref. #__________________ 

Respirator Description__________________________________________________________________ 

PASS/FAIL______________ Notes:_________________________________________________ 

 

 __________________________________________________ 

Testing Technician _______________ 

Subject # Test subject 

 ID # 

 Screening Trial: 

Number of squeezes to 

solicit a taste response 

(10, 20, 30) 

 Testing: 

 Tasted solution 

 during test? 

 Check if Yes 

Comment 

 1 

 2 

 3 

 4 

 5 

 6 

 7 

 8 

 9 

 10 

 11 

 12 

 13 

 14 

 15 

 16 

 17 

 18 

 

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Revision History 

Revision Date Reason for Revision 

1.0 29 August 2005 Establishment of test procedure 

1.1 31 August 2005 Update header and format to present version 

No changes to method 

 

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