Evaluation of Decontaminated N95 Respirators 

Date Tested: 6/12/2020 – 6/19/2020 

Respirator Model(s): Gerson 1730, Gerson 1740, 3M 1870+ 

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

Integrity with Tensile Testing 

Decontamination Method: VPHP 

Decontamination Cycles: 5, 10, and 20 cycles 

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). 

118 respirators that were unworn and not subjected to any pathogenic microorganisms were submitted for 

evaluation. This included 28 respirators that were subjected to 5 cycles of the VPHP decontamination process, 

30 respirators subjected to 10 cycles, 40 respirators subjected to 20 cycles, and 20 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. 

Filtration Efficiency Results: All respirators measured more than 95%. See Tables 1, 4, and 7. 

Manikin Fit Factor Results: The manikin fit factor showed passing fit factors (greater than 100) for all samples of 

the following respirator models/cycles; Gerson 1730 (5, 10, and 20 cycles), Gerson 1740 (20 cycles), 3M 1870+ 

(20 cycles). The manikin fit test procedure did not show passing fit factors for all samples of the following 

model/cycle; Gerson 1740 (5 and 10 cycles). See Tables 2, 5, and 8. 

Strap Integrity Results: No visual degradation of the straps was observed. 

Inconsistent changes were shown between the top and bottom straps of the following; Gerson 1730 (20 cycles), 

Gerson 1740 (10 and 20 cycles). Decreases in top and bottom strap force were shown for the following; Gerson 

1730 (5 and 10 cycles), Gerson 1740 (5 cycles), 3M 1870+ (20 cycles). See Tables 3, 6, and 9. 

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.” 
Figure 1. Laboratory Test Photos
Table 1. Filter Efficiency Evaluation – Gerson 1730

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.

Respirator Model, 

Decon Method, # 

of cycles

Treated 

Sample #

Flow Rate

(Lpm)

Initial Filter 

Resistance

(mmH2O)

Initial Percent 

Leakage (%)

Maximum 

Percent 

Leakage (%)

Filter 

Efficiency 

(%)

Gerson 1730, 

VPHP, 5 cycles

Min Fil Eff: 99.26%

Max Fil Eff: 99.65%

1 85 10.1 0.507 0.519 99.48

2 85 10.3 0.601 0.629 99.37

3 85 10.7 0.357 0.347 99.65

4 85 11.9 0.744 0.744 99.26

5 85 10.5 0.654 0.675 99.33

6 85 10.0 0.613 0.644 99.36

7 85 10.2 0.577 0.577 99.42

8 85 10.6 0.542 0.542 99.46

9 85 10.4 0.669 0.687 99.31

10 85 10.1 0.712 0.734 99.27

Control 1 85 10.3 0.567 0.567 99.43

Gerson 1730, 

VPHP, 10 cycles

Min Fil Eff: 97.77%

Max Fil Eff: 99.44%

1 85 11.8 2.23 2.23 97.77

2 85 10.0 0.557 0.557 99.44

3 85 10.2 0.583 0.628 99.37

4 85 10.0 0.710 0.710 99.29

5 85 10.6 0.898 0.903 99.10

6 85 11.7 0.640 0.640 99.36

7 85 10.5 0.615 0.615 99.39

8 85 10.1 0.716 0.716 99.28

9 85 10.0 0.695 0.695 99.31

10 85 10.0 0.654 0.654 99.35

Control 2 85 10.4 0.690 0.690 99.31

Gerson 1730, 

VPHP, 20 cycles

Min Fil Eff: 99.20%

Max Fil Eff: 99.48%

1 85 9.3 0.654 0.689 99.31

2 85 10.4 0.597 0.635 99.37

3 85 9.7 0.583 0.603 99.40

4 85 10.6 0.639 0.639 99.36

5 85 10.1 0.662 0.662 99.34

6 85 10.8 0.517 0.517 99.48

7 85 11.3 0.757 0.757 99.24

8 85 9.8 0.805 0.805 99.20

9 85 10.3 0.601 0.601 99.40

10 85 9.6 0.511 0.516 99.48

Control 1 85 10.9 0.566 0.591 99.41

Control 2 85 11.0 0.525 0.525 99.48
Table 2. Manikin Fit Evaluation - Gerson 1730

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

Gerson 1730,

VPHP, 5 cycles

Static Advanced 

Medium 

Headform 

(Hanson Robotics)

11 167 61 158 105

12 183 82 145 122

13 193 105 164 144

14 141 72 169 111

Control 3

194 100 159 140

Gerson 1730,

VPHP, 10 cycles

Static Advanced 

Medium 

Headform 

(Hanson Robotics)

11 180 117 149 144

12 200+ 146 200+ 178

13 200+ 160 184 180

14 161 88 122 117

15 200+ 200+ 200+ 200+

Control 4

200+ 87 200+ 139

Gerson 1730,

VPHP, 20 cycles

Static Advanced 

Medium 

Headform 

(Hanson Robotics)

11 200+ 156 200+ 183

12 200+ 146 200+ 178

13 200+ 196 200+ 199

14 164 92 118 118

15 200+ 199 200+ 200

Control 3

200+ 107 175 150

Control 4 200+ 92 200+ 144

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.
Table 3. Strap Integrity Evaluation – Gerson 1730

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)

Gerson 1730,

VPHP, 5 cycles

1 8.555 9.500

2 8.776 9.059

3 9.417 9.269

Decontaminated Strap 

Average 8.916 9.276

Control 1 9.953 9.332

Control Strap Average 9.266 9.657

% Change

((Deconned - Controls) / 

Controls)

-3.78% -3.95%

Gerson 1730,

VPHP, 10 cycles

1 7.630 8.873

2 7.069 7.541

3 7.628 7.813

Decontaminated Strap 

Average 7.442 8.076

Control 2 8.579 9.981

Control Strap Average 9.266 9.657

% Change

((Deconned - Controls) / 

Controls)

-19.68% -16.37%

Gerson 1730,

VPHP, 20 cycles

1 6.909 6.469

2 7.148 7.060

3 5.973 6.758

Decontaminated Strap 

Average 6.677 6.762

Control 1 6.791 7.278

Control 2 6.544 7.008

Control Strap Average 6.668 7.143

% Change

((Deconned - Controls) / 

Controls)

0.13% -5.33%
Table 4. Filter Efficiency Evaluation – Gerson 1740

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.

Respirator Model, 

Decon Method, # 

of cycles

Treated 

Sample #

Flow Rate

(Lpm)

Initial Filter 

Resistance

(mmH2O)

Initial Percent 

Leakage (%)

Maximum 

Percent 

Leakage (%)

Filter 

Efficiency 

(%)

Gerson 1740, 

VPHP, 5 cycles

Min Fil Eff: 98.82%

Max Fil Eff: 99.35%

1 85 13.3 0.997 0.997 99.00

2 85 12.5 0.753 0.753 99.25

3 85 11.7 0.796 0.800 99.20

4 85 12.0 0.651 0.651 99.35

5 85 12.4 0.664 0.664 99.34

6 85 12.3 1.03 1.03 98.97

7 85 11.6 0.908 0.908 99.09

8 85 12.0 0.906 0.918 99.08

9 85 11.2 0.768 0.768 99.23

10 85 10.1 1.17 1.18 98.82

Control 1 85 11.4 0.870 0.871 99.13

Gerson 1740, 

VPHP, 10 cycles

Min Fil Eff: 98.47%

Max Fil Eff: 99.40%

1 85 12.2 0.873 0.873 99.13

2 85 11.4 1.02 1.02 98.98

3 85 12.1 1.07 1.07 98.93

4 85 13.1 0.596 0.596 99.40

5 85 11.1 1.13 1.13 98.87

6 85 12.9 0.964 0.964 99.04

7 85 11.3 1.07 1.08 98.92

8 85 11.6 0.846 0.862 99.14

9 85 11.4 1.53 1.53 98.47

10 85 12.2 0.898 0.898 99.10

Control 2 85 10.9 1.20 1.20 98.80

Gerson 1740, 

VPHP, 20 cycles

Min Fil Eff: 98.58%

Max Fil Eff: 99.36%

1 85 12.0 0.945 0.945 99.06

2 85 11.8 0.832 0.832 99.17

3 85 12.2 0.898 0.898 99.10

4 85 12.2 0.814 0.815 99.19

5 85 11.1 1.19 1.19 98.81

6 85 12.5 0.639 0.639 99.36

7 85 12.0 1.41 1.42 98.58

8 85 10.9 1.14 1.15 98.85

9 85 12.0 0.859 0.859 99.14

10 85 12.4 1.01 1.03 98.97

Control 1 85 12.2 0.715 0.838 99.16

Control 2 85 12.8 0.663 0.663 99.34
Table 5. Manikin Fit Evaluation - Gerson 1740

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

Gerson 1740,

VPHP, 5 cycles

Static Advanced 

Medium 

Headform 

(Hanson Robotics)

11 171 83 112 112

12 190 109 163 146

13 200+ 114 125 138

14 105 72 93 88

Control 3

133 86 123 110

Gerson 1740,

VPHP, 10 cycles

Static Advanced 

Medium 

Headform 

(Hanson Robotics)

11 196 89 139 127

12 105 66 85 82

13 72 56 79 68

14 123 74 103 96

15 200+ 135 200+ 173

Control 4

130 80 135 109

Gerson 1740,

VPHP, 20 cycles

Static Advanced 

Medium 

Headform 

(Hanson Robotics)

11 136 97 127 118

12 200+ 200+ 200+ 200+

13 200+ 155 190 180

14 185 95 115 122

15 123 96 114 109

Control 3

200+ 133 189 168

Control 4 187 101 133 132

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 6. Strap Integrity Evaluation – Gerson 1740

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)

Gerson 1740,

VPHP, 5 cycles

1 7.775 6.855

2 8.359 7.178

3 7.445 7.841

Decontaminated Strap 

Average 7.860 7.291

Control 1 9.080 7.902

Control Strap Average 9.165 7.635

% Change

((Deconned - Controls) / 

Controls)

-14.24% -4.51%

Gerson 1740,

VPHP, 10 cycles

1 9.080 7.602

2 8.389 8.010

3 8.823 8.635

Decontaminated Strap 

Average 8.764 8.082

Control 2 9.250 7.367

Control Strap Average 9.165 7.635

% Change

((Deconned - Controls) / 

Controls)

-4.38% 5.85%

Gerson 1740,

VPHP, 20 cycles

1 7.140 7.253

2 7.238 5.714

3 7.530 6.151

Decontaminated Strap 

Average 7.303 6.373

Control 1 7.770 6.719

Control 2 6.651 7.260

Control Strap Average 7.211 6.990

% Change

((Deconned - Controls) / 

Controls)

1.28% -8.83%
Table 7. Filter Efficiency Evaluation – 3M 1870+

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. 

Respirator Model, 

Decon Method, # 

of cycles

Treated 

Sample #

Flow Rate

(Lpm)

Initial Filter 

Resistance

(mmH2O)

Initial Percent 

Leakage (%)

Maximum 

Percent 

Leakage (%)

Filter 

Efficiency 

(%)

3M 1870+, VPHP,

20 cycles

Min Fil Eff: 98.00%

Max Fil Eff: 99.78%

1

85 7.5 1.58 1.77 98.23

2

85 7.8 0.093 0.225 99.78

3

85 8.3 0.655 0.762 99.24

4

85 7.6 1.12 2.00 98.00

5

85 7.3 1.12 1.22 98.78

6

85 7.9 0.560 0.747 99.25

Control 1 85 7.7 0.343 0.467 99.53

Control 2 85 8.4 0.023 0.166 99.83
Table 8. Manikin Fit Evaluation - 3M 1870+

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 1870+, VPHP,

20 cycles

Static Advanced 

Medium 

Headform 

(Hanson Robotics)

7

200+ 200+ 200+ 200+

8

200+ 200+ 200+ 200+

9

200+ 200+ 200+ 200+

10 200+ 181 200+ 193

Control 3

200+ 200+ 200+ 200+

Control 4

200+ 200+ 200+ 200+

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.

Table 9. Strap Integrity Evaluation - 3M 1870+

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 1870+, VPHP, 20 cycles

1 1.456 1.426

2 1.600 1.372

3 1.536 1.364

Decontaminated Strap 

Average 1.531 1.387

Control 1 1.886 1.639

Control 2 1.728 1.737

Control Strap Average 1.807 1.688

% Change

((Deconned - Controls) / 

Controls)

-15.27% -17.83%