1

Evaluation of Decontaminated N95 Respirators 

Date Tested: 12/1/2020 – 12/4/2020

Respirator Model(s): 3M 1860 and 3M 8210 

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

Integrity with Tensile Testing 

Decontamination Method: MSU Extension Dry Heat Decontamination System for N95 Respirators. This system uses dry 

heat at 85 °C (185 °F) for 50 minutes. This allows for come-up temperature of masks and any variation in oven temperature 

throughout the cycle to achieve the Critical Control Point of 75°C (167°F) for 30 minutes. 

Decontamination Cycles: 4 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). 

Fifty-three respirators that were unworn and not subjected to any pathogenic microorganisms were submitted 

for evaluation. This included 43 respirators that were subjected to 4 cycles of the Dry Heat 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-APRSTP-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 and 3M 8210 treated samples had observable blurring of the printed information 

found on the front of the respirators. Discoloration of the 3M 1860 treated straps were also noted. Figures 1A1C show a comparison between a control sample and a treated sample of these observations. 

3M 1860

Filtration Efficiency Results: The minimum and maximum filter efficiencies were 98.14% and 99.02%, 

respectively. All respirators measured more than 95%. See Table 1. 

Manikin Fit Factor Results: The manikin fit factor showed passing fit factors (≥ 100) for the controls and five out 

of the six treated respirators evaluated. One of the treated respirators had a failing fit factor (< 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.” 
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Strap Integrity Results: The top straps showed a 16.98% increase in recorded force and the bottom straps 

showed a 2.08% increase in force. See Table 3.

3M 8210

Filtration Efficiency Results: The minimum and maximum filter efficiencies were 97.33% and 99.96%, 

respectively. All respirators measured more than 95%. See Table 4. 

Manikin Fit Factor Results: The manikin fit factor showed passing fit factors (≥ 100) for all respirators evaluated.

See Table 5. 

Strap Integrity Results: The top straps showed a 19.71% increase in recorded force and the bottom straps 

showed a 42.90% increase in force. See Table 6.
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Figure 1. Sample Observations 

Fig. 1A. 3M 1860 Printed Information. Control (Left), Treated (Right)

Fig. 1B. 3M 8210 Printed Information. Control (Left), Treated (Right)

Fig. 1C. 3M 1860 Strap Discoloration. Control (Left), Treated (Right)

A

B

C
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Figure 2. Laboratory Test Photos

Fig. 2A. Medium Static Advanced Headform. 3M 1860 (Left), 3M 8210 (Right)

Fig. 2B. Instron 5943 Tensile Tester

Fig. 2C. TSI 8130 Filter Tester 3M 1860 (Left), 3M 8210 (Right)

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.

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 11.4 0.712 0.717 99.28

Control 2 85 9.0 0.413 0.672 99.33

Control 3 85 11.3 0.936 0.986 99.01

3M 1860, Dry 

Heat, 4 cycles 

Min Fil Eff: 98.14%

Max Fil Eff: 99.02%

1 85 8.1 0.534 0.990 99.01

2 85 7.9 0.722 1.150 98.85

3 85 8.5 0.561 0.980 99.02

4 85 8.4 0.807 1.370 98.63

5 85 8.9 0.649 1.090 98.91

6 85 8.8 0.541 1.020 98.98

7 85 9.3 0.729 1.180 98.82

8 85 8.9 0.521 1.130 98.87

9 85 8.5 0.961 1.860 98.14

10 85 8.5 0.654 1.100 98.90

11 85 11.2 1.04 1.300 98.70

12 85 9.0 0.884 1.540 98.46

13 85 10.0 0.799 1.230 98.77

14 85 9.8 0.826 1.550 98.45

15 85 8.5 0.969 1.710 98.29
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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 

Control 4 200+ 200+ 200+ 200+

Control 5 200+ 200+ 200+ 200+

3M 1860, Dry 

Heat, 4 Cycles 

Static Advanced 

Medium Headform 

(Hanson Robotics)

16 200+ 125 164 157

17 200+ 180 200+ 193

18 200+ 172 200+ 190

19 200+ 200+ 200+ 200+

20 84 58 55 64

21 166 77 197 125

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 2.657 2.426

Control 2 2.755 2.460

Control 3 2.767 2.485

Control Strap Average 2.726 2.457

3M 1860, Dry Heat, 4 cycles 

1 3.341 2.626

2 2.969 2.533

3 3.113 2.383

4 3.333 2.490

Decontaminated Strap 

Average 3.189 2.508

% Change

((Deconned - Controls)/ 

Controls)

16.98% 2.08%
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Table 4. Filter Efficiency Evaluation – 3M 8210

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, Controls

Control 1 85 11.1 0.869 0.869 99.13

Control 2 85 9.8 0.700 0.280 99.72

Control 3 85 9.0 0.094 2.090 97.91

3M 8210, Dry 

Heat, 4 cycles 

Min Fil Eff: 97.33%

Max Fil Eff: 99.96%

1 85 7.7 0.234 0.554 99.45

2 85 9.9 0.098 0.286 99.71

3 85 8.6 0.265 0.558 99.44

4 85 9.1 0.136 0.352 99.65

5 85 8.8 1.840 2.380 97.62

6 85 9.4 0.076 0.265 99.74

7 85 9.6 0.860 0.907 99.09

8 85 11.3 1.950 2.010 97.99

9 85 8.8 1.110 1.290 98.71

10 85 10.9 0.428 0.428 99.57

11 85 12.8 0.696 0.768 99.23

12 85 9.0 0.297 0.677 99.32

13 85 9.3 0.660 0.982 99.02

14 85 9.4 2.560 2.670 97.33

15 85 10.0 0.086 0.040 99.96
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Table 5. Manikin Fit Evaluation – 3M 8210

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 8210, Controls 

Control 4 200+ 174 200+ 191

Control 5 200+ 183 200+ 194

3M 8210, Dry 

Heat, 4 Cycles 

Static Advanced 

Medium Headform 

(Hanson Robotics)

16 200+ 200+ 200+ 200+

17 200+ 200+ 200+ 200+

18 200+ 200+ 200+ 200+

19 200+ 200+ 200+ 200+

20 200+ 174 200+ 191

21 200+ 200+ 200+ 200+

22 200+ 200+ 171 189

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 8210

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 8210, Controls 

Control 1 4.372 4.396

Control 2 4.594 4.542

Control 3 4.379 4.399

Control Strap Average 4.448 4.446

3M 8210, Dry Heat, 4 cycles 

1 5.258 6.502

2 5.065 6.247

3 5.663 6.417

4 5.312 6.248

Decontaminated Strap 

Average 5.325 6.354

% Change

((Deconned - Controls)/ 

Controls)

19.71% 42.90%