Evaluation of Decontaminated N95 Respirators

Date(s) Tested: 4/15/2020-4/20/2020

Respirator Model(s): 3M 1860, 3M1860S, Moldex 1512 Medium, Moldex 2200 M/L, 3M 8210, 3M V-flex 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: VPHP 

Decontamination Cycles: 5 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). 

Sixty respirators, of varying manufacturers/models, that were unworn and not subjected to any pathogenic 

microorganisms were submitted for evaluation. This included 50 respirators that were subjected to 5 cycles of 

the VPHP decontamination process and an additional 10 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: The maximum and minimum filter efficiency were as follows; Moldex 2200 M/L 

(99.25% and 97.54%); Moldex 1512 Medium (99.12% and 96.25%); 3M 8210 (99.72% and 99.48%); 3M 1860 

(99.54% and 99.26%); 3M 1860S (99.73% and 99.01%); 3M V-flex 1804 (99.71% and 99.50%). All samples of all 

six respirator models had filtration efficiencies measured more than 95%. See Table 1 for Moldex respirators 

and Table 4 for 3M respirators. 

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

the following models; Moldex 1512 Medium; 3M 8210; 3M 1860; 3M 1860S; 3M V-flex 1804. See Table 2 for 

Moldex respirators and Table 5 for 3M respirators. 

The manikin fit factor did not show consistent passing fit factors for the following model; Moldex 2200 M/L 

(range = 34-200+). 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.” 
The manikin fit test procedure used in this assessment did not show any detriments in fit associated with the 

decontamination method used for all models, except for the Moldex 2200 M/L. Small changes in fit factors may 

be attributed to manufacturing variation, variation in donning on the manikin, the decontamination method, or 

a combination of these factors. Larger variations, as seen in this model, may require further research to 

understand the cause. 

Strap Integrity Results: No visual degradation of the straps was observed. Decreases in recorded force of the 

treated samples were found in the following models for both top and bottom straps, respectively; Moldex 1512 

Medium (11.32% and 9.49%); 3M 8210 (1.22% and 12.68%)

Increases in recorded force of the treated samples were found in the following models for both top and bottom 

straps, respectively; 3M 1860S (17.62% and 16.49%); 3M V-flex 1804 (7.41% and 8.76%).

Inconsistent changes were shown between top and bottom straps for the Moldex 2200 M/L, with the top straps 

showing a 4.92% increase in recorded force and the bottom a 5.00% decrease. This respirator also showed a 

significant detriment in fit. Changes in strap integrity could not be measured for the 3M 1860, as no controls 

were provided.

While the exact correlation between the force exerted by straps and fit is not well understood, higher force 

values may be associated with a tighter fit of the respirator to the face. Significant reductions in this force would 

be associated with a loss of elasticity of the straps, thereby reducing their ability to create a tight fit. See Table 3

for Moldex respirators and Table 6 for 3M respirators.
Figure 1. Laboratory test photos from a portion of the respirators evaluated 
Table 1. Filter Efficiency Evaluation – Moldex Respirators 

*Instantaneous test only

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

(%)

Moldex 2200 M/L, 

VPHP, 5 cycles

Minimum Filter 

Efficiency: 97.54%

Maximum Filter 

Efficiency: 99.25%

1

85 11.5 1.56 1.56 98.44%

2

85 10.6 1.64 1.64 98.36%

3

85 12.1 0.746 0.746 99.25%

4

85 9.9 2.14 2.46 97.54%

5

85 10.6 1.31 1.31 98.69%

6

85 11.2 1.83 1.83 98.17%

7

85 10.2 1.53 1.53 98.47%

8

85 11.7 0.792 0.792 99.21%

Control 1 85 11.0 1.66 n/a * 98.34%

Moldex 1512 Medium, 

VPHP, 5 cycles

Minimum Filter 

Efficiency: 96.25%

Maximum Filter 

Efficiency: 99.12%

1 85 9.5 2.94 3.11 96.89%

2

85 8.9 1.22 2.59 97.41%

3

85 9.1 1.31 3.75 96.25%

4

85 9.2 1.24 1.24 98.76%

5

85 9.1 0.915 0.915 99.09%

6

85 9.1 1.01 1.01 98.99%

7

85 9.2 0.884 0.884 99.12%

8

85 8.7 1.12 1.12 98.88%

Control 1 85 9.3 1.43 1.43 98.57%
Table 2. Manikin Fit Evaluations – Moldex Respirators 

Static Advanced Medium Headform (Hanson Robotics)

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 less than 100.

Manikin Fit Factor (mFF) 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

Moldex 2200 

M/L, VPHP, 5 

cycles

9

200+ 200+ 200+ 200+

10 84 58 99 77

11 34 38 30 34

12 200+ 191 200+ 197

Control 2 200+ 146 142 159

Moldex 1512 

Medium, VPHP, 5 

cycles

9

146 95 107 112

10 200+ 200+ 200+ 200+

11 200+ 200+ 200+ 200+

12 200+ 200+ 200+ 200+

Control 2 165 116 120 131
Table 3. Strap Integrity Evaluation of Moldex Respirators 

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)

Moldex 2200 M/L, 

VPHP, 5 cycles

1 n/a * 4.442

2 5.397 n/a *

3 5.318 5.059

Decontaminated Strap 

Average 5.358 4.751

Control 1 5.107 5.001

% Change

((Deconned - Control) / 

Control)

4.92% -5.00%

Moldex 1512 Medium, 

VPHP, 5 cycles

Straps from Treated Sample # Force in Top Strap (N) Force in Bottom Strap 

(N)

1 3.162 2.850

2 3.139 3.131

3 2.986 3.028

Decontaminated Strap 

Average 3.096 3.003

Control 1 3.491 3.318

% Change

((Deconned - Control) / 

Control)

-11.32% -9.49%

*Technical difficulties during testing. Results not reportable.
Table 4. Filter Efficiency Evaluation – 3M Respirators 

*instantaneous test only

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 8210, 

VPHP, 5 cycles

Min Fil Eff: 

99.48%

Max Fil Eff: 

99.72%

1

85 7.7 0.128 0.300 99.70%

2

85 7.1 0.227 0.498 99.50%

3

85 7.4 0.155 0.445 99.56%

4

85 7.4 0.185 0.517 99.48%

5

85 7.1 0.100 0.280 99.72%

Control 1 85 7.7 0.157 n/a * 99.84%

3M 1860, 

VPHP, 5 cycles

Min Fil Eff: 

99.26%

Max Fil Eff: 

99.54%

1 85 8.7 0.544 0.744 99.26%

2 85 9.5 0.317 0.457 99.54%

3 85 9.9 0.359 0.479 99.52%

4 85 9.8 0.433 0.601 99.40%

5 85 9.7 0.338 0.492 99.51%

3M 1860S, 

VPHP, 5 cycles

Min Fil Eff: 

99.01%

Max Fil Eff: 

99.73%

1 85 11.0 0.672 0.987 99.01%

2 85 11.0 0.497 0.769 99.23%

3 85 11.6 0.669 2.27 97.73%

Control 1 85 13.9 0.699 0.699 99.30%

3M VFlex 1804, 

VPHP, 5 cycles

Min Fil Eff: 

99.50%

Max Fil Eff: 

99.71%

1 85 4.7 0.465 0.502 99.50%

2 85 4.5 0.330 0.402 99.60%

3 85 4.9 0.263 0.350 99.65%

4 85 4.8 0.209 0.295 99.71%

5 85 4.8 0.231 0.291 99.71%

Control 1 85 4.6 0.214 0.282 99.72%
Table 5. Manikin Fit Evaluation – 3M Respirators

Static Advanced Medium Headform (Hanson Robotics)

Manikin Fit Factor (mFF) 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 8210, VPHP, 5 

cycles

6

200+ 200+ 200+ 200+

7

200+ 200+ 200+ 200+

Control 2 200+ 200+ 200+ 200+

3M 1860, VPHP, 5 

cycles

6

200+ 168 200+ 188

7

200+ 200+ 200+ 200+

Control No control provided.

3M 1860S, VPHP, 

5 cycles

4

200+ 200+ 200+ 200+

5

200+ 105 200+ 154

6

200+ 168 200+ 188

Control 2 200+ 200+ 200+ 200+

3M VFlex 1804, 

VPHP, 5 cycles

6

200+ 200+ 200+ 200+

7

148 111 116 123

Control 2 200+ 164 199 186

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 6. Strap Integrity Evaluation - 3M Respirators

Tensile Force in Respirator Straps of Decontaminated 

N95s (recorded force values are at 150% strain) 

3M 8210, 

VPHP, 5 

cycles

Straps from Treated Sample # Force in Top Strap (N) Force in Bottom Strap (N)

1 4.412 4.151

2 4.434 4.009

3 4.267 3.985

Decontaminated Strap 

Average 4.371 4.048

Control 1 4.425 4.652

% Change

((Deconned - Control) / 

Control)

-1.22% -12.68%

3M 1860, 

VPHP, 5 

cycles

Straps from Treated Sample # Force in Top Strap (N) Force in Bottom Strap (N)

1 3.079 3.332

2 2.923 3.486

3 3.026 3.341

Decontaminated Strap 

Average 3.009 3.386

Control 1

% Change No control provided.

((Deconned - Control) / 

Control)

3M 1860S, 

VPHP, 5 

cycles

Straps from Treated Sample # Force in Top Strap (N) Force in Bottom Strap (N)

1 3.670 3.381

2 3.523 3.400

3 3.615 3.263

Decontaminated Strap 

Average 3.603 3.348

Control 1 2.968 2.874

% Change

((Deconned - Control) / 

Control)

17.62% 16.49%

3M VFlex

1804, VPHP, 

5 cycles

Straps from Treated Sample # Force in Top Strap (N) Force in Bottom Strap (N)

1 2.589 2.721

2 2.490 2.647

3 2.309 2.601

Decontaminated Strap 

Average 2.463 2.656

Control 1 2.293 2.442

% Change

((Deconned - Control) / 

Control)

7.41% 8.76%