1

Evaluation of Decontaminated N95 Respirators 

Date Tested: 11/17/2020 – 11/19/2020 

Respirator Model(s): 3M 1860, 3M 1860S, 3M VFlex 1804 

Tests: Filtration with NaCl (modified version of STP-0059), Manikin Fit Factor with Static Advanced Headform, and Strap 

Integrity with Tensile Testing 

Decontamination Method: New FFRs were decontaminated with dense-phase carbon dioxide at 37°C above its 

supercritical pressure of 1100 psig with humidification for 90 minutes.

Decontamination Cycles: 1 cycle 

While decontamination and reuse of FFRs are not consistent with standard and approved usage, these options may need to 

be considered when FFR shortages exist. This assessment was developed to quantify the filtration efficiency and manikin fit 

factor1 of an N95 respirator that has been decontaminated. This assessment is not to determine the effectiveness of the 

decontamination procedure at killing pathogenic microorganisms. The results provided in this report are specific to the 

subset of samples that were provided to NPPTL for evaluation. These results may be used to update the CDC guidance for 

Crisis Capacity Strategies (during known shortages). 

Thirty-one respirators that were unworn and not subjected to any pathogenic microorganisms were submitted for 

evaluation. This included 19 respirators that were subjected to 1 cycle of the supercritical carbon dioxide decontamination 

process and an additional 12 respirators that served as controls. Figure 1 photos document the procedures used. The 

samples were tested using a modified version of the NIOSH Standard Test Procedure (STP) TEB-APR-STP-0059 to determine 

particulate filtration efficiency. The TSI, Inc. model 8130 using sodium chloride aerosol was used for the filtration 

evaluation. For the laboratory fit evaluation, a static manikin headform was used to quantify changes in manikin fit factor. 

The TSI, Inc. PortaCount® PRO+ 8038 in “N95 Enabled” mode was used for this evaluation. Additionally, tensile strength 

testing of the straps was performed to determine changes in strap integrity. The Instron® 5943 Tensile Tester was used for 

this evaluation. The full assessment plan can be found here. 

Other notes: The 3M 1860, 3M 1860S and 3M VFlex 1804 treated respirators had observable fading of the printed 

information found on the outside and discoloration of the nosefoam and respirator material on the inside. Figure 1A-1E 

shows a comparison between a control sample and a treated sample of the noted respirator models. A strong odor and 

overall stiffness of the treated respirators was also observed. 

3M 1860

Filtration Efficiency Results: The minimum and maximum filter efficiencies were 55.70% and 74.70%, respectively. All four 

treated respirators measured efficiencies less than the passing 95%. See Table 1. 

Manikin Fit Factor Results: The manikin fit factor showed passing fit factors (≥100) for the two control respirators 

evaluated. The two treated samples received failing fit factors (< 100). See Table 2. 

1The American Industrial Hygiene Association defines the Manikin Fit Factor as “An expression related to the amount of leakage measured through the 

face or neck seal of a respirator mounted to a manikin under specified airflow and environmental conditions. If the challenge to the seal is an airborne 

substance, it is the ratio of its airborne concentration outside the respirator divided by the concentration that enters the respirator through the seal. If the 

challenge is airflow or air pressure, conditions and assumptions for quantifying leakage must be specified. Leakage from other sources (e.g., air purifying 

elements) must be essentially zero. The respirator may be mounted to the manikin without sealants; be partially sealed to the manikin; or be sealed to the 

manikin with artificially induced leaks.” 
2

Strap Integrity Results: The top straps showed a 9.38% increase in recorded force and the bottom straps showed a 8.73% 

increase in force. See Table 3.

3M 1860S

Filtration Efficiency Results: The minimum and maximum filter efficiencies were 57.70% and 84.90%, respectively. All five 

treated respirators measured efficiencies less than the passing 95%. See Table 4.

Manikin Fit Factor Results: The manikin fit factor showed passing fit factors (≥100) for the two control respirators 

evaluated. The two treated samples received failing fit factors (< 100). See Table 5. 

Strap Integrity Results: The top straps showed a 5.62% increase in recorded force and the bottom straps showed a 10.16% 

increase in force. See Table 6. 

3M VFlex 1804

Filtration Efficiency Results: The minimum and maximum filter efficiencies were 82.00% and 91.79%, respectively. All four 

treated respirators measured efficiencies less than the passing 95%. See Table 7.

Manikin Fit Factor Results: The manikin fit factor showed passing fit factors (≥100) for both the control and treated 

respirators. See Table 8. 

Strap Integrity Results: The top straps showed a 1.55% increase in recorded force and the bottom straps showed a 10.26% 

increase in force. See Table 9.
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Figure 1. Sample Observations 

Fig. 1A. 3M 1860 Outside Control (Left), Treated (Right) Fig. 1B. 3M 1860 Inside Control (Left), Treated (Right)

Fig. 1C. 3M 1860S Outside Control (Left), Treated (Right) Fig. 1D. 3M 1860S Inside Control (Left), Treated (Right)

Fig. 1E. 3M VFlex 1804 Outside Control (Left), Treated (Right)

A B

C D

E
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Figure 2. Laboratory Test Photos

Fig. 2A. Medium Static Advanced Headform (left to right: 3M 1860, 3M 1860S, VFlex 1804)

Fig. 2B. Instron 5943 Tensile Tester 

Fig. 2C. TSI 8130 Filter Tester (left to right: 3M 1860, VFlex 1804)

A

B

C
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Table 1. Filter Efficiency Evaluation – 3M 1860 

Notes:

• The test method utilized in this assessment is not the NIOSH standard test procedure that is used for certification

of respirators. Respirators assessed to this modified test plan do not necessarily meet the requirements of STP0059, and therefore cannot be considered equivalent to N95 respirators that were tested to STP-0059.

• BOLD filter efficiencies < 95%.

Respirator Model, 

Decon Method, # 

of cycles

Treated 

Sample #

Flow Rate

(Lpm)

Initial Filter 

Resistance

(mmH2O)

Initial Percent 

Leakage (%)

Maximum 

Percent 

Leakage (%)

Filter 

Efficiency 

(%)

3M 1860, Controls

Control 1 85 9.0 0.424 0.783 99.22

Control 2

85 8.9 0.350 0.577 99.42

3M 1860, 

Supercritical CO2, 

1 cycle

Min Fil Eff: 55.70%

Max Fil Eff: 74.70%

1

85 9.9 25.3 25.3 74.70

2

85 9.6 43.4 44.3 55.70

3

85 8.9 41.0 41.0 59.00

4

85 9.1 39.7 39.7 60.30
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Table 2. Manikin Fit Evaluation – 3M 1860 

Manikin Fit Factor of Decontaminated N95s

Respirator Model, 

Decon Method, # 

of cycles

Treated

Sample #

mFF Normal 

Breathing 1

mFF Deep 

Breathing

mFF Normal 

Breathing 2

Overall 

Manikin Fit 

Factor

3M 1860, Controls

Static Advanced 

Medium Headform 

(Hanson Robotics)

Control 3 200+ 151 200+ 181

Control 4 200+ 200+ 200+ 200+

3M 1860, 

Supercritical CO2, 

1 cycle 

Static Advanced 

Medium Headform 

(Hanson Robotics)

5

74 24 59 42

6

88 13 23 22

Notes:

• Per OSHA 1910.134(f)(7), if the fit factor as determined through an OSHA-accepted quantitative fit testing protocol 

is equal to or greater than 100 for tight-fitting half facepieces, then the fit test has been passed for that respirator.

• This assessment does not include fit testing of people and only uses two exercises (normal and deep breathing) on 

a manikin headform. 

• This assessment is a laboratory evaluation using a manikin headform and varies greatly from the OSHA individual 

fit test. This headform testing only includes normal breathing and deep breathing on a stationary (non-moving) 

headform; therefore, fit results from this assessment cannot be directly translated to using the standard OSHAaccepted test. Instead, this testing provides an indication of the change in fit performance (if any) associated with 

the decontamination of respirators. 

• BOLD overall manikin fit factors < 100.

Table 3. Strap Integrity Evaluation – 3M 1860 

Tensile Force in Respirator Straps of Decontaminated N95s

(recorded force values are at 150% strain)

Respirator Model, Decon 

Method, # of cycles Straps from Treated Sample # Force in Top Strap (N)

Force in Bottom 

Strap (N)

3M 1860, Controls 

Control 1 2.757 3.110

Control 2 2.797 3.242

Control Strap Average 2.777 3.176

3M 1860, Supercritical CO2, 

1 cycle

1 3.009 3.367

2 3.097 3.319

3 3.043 3.485

4 3.001 3.642

Decontaminated Strap 

Average 3.038 3.453

% Change 

((Deconned – Controls)/ 

Controls)

9.38% 8.73%
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Table 4. Filter Efficiency Evaluation – 3M 1860S

Notes:

• The test method utilized in this assessment is not the NIOSH standard test procedure that is used for certification 

of respirators. Respirators assessed to this modified test plan do not necessarily meet the requirements of STP0059, and therefore cannot be considered equivalent to N95 respirators that were tested to STP-0059. 

• BOLD filter efficiencies < 95%.

Respirator Model, 

Decon Method, # 

of cycles

Treated 

Sample #

Flow Rate

(Lpm)

Initial Filter 

Resistance

(mmH2O)

Initial Percent 

Leakage (%)

Maximum 

Percent 

Leakage (%)

Filter 

Efficiency 

(%)

3M 1860S, 

Controls

Control 1 85 12.5 0.395 0.783 99.22

Control 2

85 13.8 0.361 0.577 99.42

3M 1860S, 

Supercritical CO2, 1 

cycle 

Min Fil Eff: 57.70%

Max Fil Eff: 84.90%

1

85 12.6 41.30 42.00 58.00

2

85 12.3 40.60 41.60 58.40

3

85 12.2 42.30 42.30 57.70

4

85 11.8 37.10 38.60 61.40

5

85 14.1 14.70 15.10 84.90
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Table 5. Manikin Fit Evaluation – 3M 1860S

Manikin Fit Factor of Decontaminated N95s

Respirator Model, 

Decon Method, # 

of cycles

Treated

Sample #

mFF Normal 

Breathing 1

mFF Deep 

Breathing

mFF Normal 

Breathing 2

Overall 

Manikin Fit 

Factor

3M 1860S, 

Controls

Static Advanced 

Medium Headform 

(Hanson Robotics)

Control 3 200+ 183 200+ 194

Control 4 200+ 200+ 200+ 200+

3M 1860S, 

Supercritical CO2, 

1 cycle 

Static Advanced 

Medium Headform 

(Hanson Robotics)

6

11 6 10 8

7

19 8 26 13

Notes:

• Per OSHA 1910.134(f)(7), if the fit factor as determined through an OSHA-accepted quantitative fit testing protocol is equal to 

or greater than 100 for tight-fitting half facepieces, then the fit test has been passed for that respirator.

• This assessment does not include fit testing of people and only uses two exercises (normal and deep breathing) on a manikin 

headform. 

• This assessment is a laboratory evaluation using a manikin headform and varies greatly from the OSHA individual fit test. This 

headform testing only includes normal breathing and deep breathing on a stationary (non-moving) headform; therefore, fit 

results from this assessment cannot be directly translated to using the standard OSHA-accepted test. Instead, this testing 

provides an indication of the change in fit performance (if any) associated with the decontamination of respirators. 

• BOLD overall manikin fit factors < 100.

Table 6. Strap Integrity Evaluation – 3M 1860S

Tensile Force in Respirator Straps of Decontaminated N95s

(recorded force values are at 150% strain)

Respirator Model, Decon 

Method, # of cycles Straps from Treated Sample # Force in Top Strap (N)

Force in Bottom 

Strap (N)

3M 1860S, Controls 

Control 1 4.343 3.750

Control 2 4.353 3.590

Control Strap Average 4.348 3.670

3M 1860S, Supercritical CO2, 

1 cycle

1 4.614 4.033

2 4.578 4.057

3 4.626 4.051

4 4.551 4.031

Decontaminated Strap 

Average 4.592 4.043

% Change 

((Deconned – Controls)/ 

Controls)

5.62% 10.16%
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Table 7. Filter Efficiency Evaluation – 3M VFlex 1804

Notes:

• The test method utilized in this assessment is not the NIOSH standard test procedure that is used for certification

of respirators. Respirators assessed to this modified test plan do not necessarily meet the requirements of STP-0059, and 

therefore cannot be considered equivalent to N95 respirators that were tested to STP-0059.

• BOLD filter efficiencies < 95%.

Respirator Model, 

Decon Method, # 

of cycles

Treated 

Sample #

Flow Rate

(Lpm)

Initial Filter 

Resistance

(mmH2O)

Initial Percent 

Leakage (%)

Maximum 

Percent 

Leakage (%)

Filter 

Efficiency 

(%)

3M VFlex 1804, 

Controls

Control 1 85 4.5 0.132 0.223 99.78

Control 2

85 4.9 0.308 0.448 99.55

3M VFlex 1804, 

Supercritical CO2, 

1 cycle

Min Fil Eff: 82.00%

Max Fil Eff: 91.79%

1

85 5.4 8.870 10.30 89.70

2

85 4.7 16.80 18.00 82.00

3

85 4.5 11.00 11.50 88.50

4

85 4.7 7.630 8.210 91.79
10

Table 8. Manikin Fit Evaluation – 3M VFlex 1804

Manikin Fit Factor of Decontaminated N95s

Respirator Model, 

Decon Method, # 

of cycles

Treated

Sample #

mFF Normal 

Breathing 1

mFF Deep 

Breathing

mFF Normal 

Breathing 2

Overall 

Manikin Fit 

Factor

3M VFlex 1804, 

Controls

Static Advanced 

Medium Headform 

(Hanson Robotics)

Control 3 200+ 200+ 200+ 200+

Control 4 200+ 200+ 200+ 200+

3M VFlex 1804, 

Supercritical CO2, 

1 cycle 

Static Advanced 

Medium Headform 

(Hanson Robotics)

5

200+ 67 200+ 121

6

200+ 132 200+ 171

Notes:

• Per OSHA 1910.134(f)(7), if the fit factor as determined through an OSHA-accepted quantitative fit testing protocol is equal to

or greater than 100 for tight-fitting half facepieces, then the fit test has been passed for that respirator.

• This assessment does not include fit testing of people and only uses two exercises (normal and deep breathing) on a manikin 

headform.

• This assessment is a laboratory evaluation using a manikin headform and varies greatly from the OSHA individual fit test. This 

headform testing only includes normal breathing and deep breathing on a stationary (non-moving) headform; therefore, fit

results from this assessment cannot be directly translated to using the standard OSHA-accepted test. Instead, this testing 

provides an indication of the change in fit performance (if any) associated with the decontamination of respirators.

Table 9. Strap Integrity Evaluation – 3M VFlex 1804

Tensile Force in Respirator Straps of Decontaminated N95s

(recorded force values are at 150% strain)

Respirator Model, Decon

Method, # of cycles

Straps from Treated Sample 

#

Force in Top 

Strap (N)

Force in Bottom 

Strap (N)

3M VFlex 1804, Controls 

Control 1 3.007 2.678

Control 2 3.058 2.699

Control Strap Average 3.033 2.689

3M VFlex 1804, Supercritical CO2, 

1 cycle

1 2.838 2.935

2 3.192 2.869

3 3.112 2.989

4 3.178 3.067

Decontaminated Strap 

Average 3.080 2.965

% Change 

((Deconned – Controls)/ 

Controls)

1.55% 10.26%