Evaluation of Decontaminated N95 Respirators 

Date Tested: 5/8/2020 – 5/12/2020 

Respirator Model(s): 3M 8511, 3M 1860, Halyard 62126

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

Integrity with Tensile Testing 

Decontamination Method: Heat-based decontamination method using commercial laundry dryers. FFRs are placed in 

sealed Ziploc bags inside boxes installed in dryer tumbler. 3 cycles at 70°C for 60 min.

Decontamination Cycles: 3 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). 

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

evaluation. This included 45 respirators that were subjected to 3 cycles of the dry heat decontamination process 

and an additional 15 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 minimum and maximum filter efficiencies were the following; 3M 1860 

(98.53% and 99.33%); 3M 8511 (99.09% and 99.82%); Halyard 62126 (99.18% and 99.78%). All respirators 

measured more than 95%. See Tables 1 and 4. 

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

evaluated. The manikin fit test procedure used in this assessment did not show any detriments in fit associated 

with the decontamination method used. See Tables 2 and 5. 

Strap Integrity Results: No visual degradation of the straps was observed. All models showed decreases in 

recorded force for the top and bottom straps, respectively; 3M 1860 (1.76% and 3.24%); 3M 8511 (4.77% and 

3.69%); Halyard 62126 (4.38% and 3.29%). 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. 

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.” 
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. 

Other notes: The respirator information text on the front of the 3M 1860 was blurred and illegible. The 

respirator name on the front of the Halyard 62126 was also blurred and illegible.
Figure 1. Laboratory Test Photos
Table 1. Filter Efficiency Evaluation – 3M

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, dry heat, 

3 cycles

Min Fil Eff: 98.53%

Max Fil Eff: 99.33%

1

85 9.1 0.525 0.763 99.24

2

85 8.9 1.06 1.47 98.53

3

85 9.6 0.534 0.853 99.15

4

85 9.0 0.468 0.671 99.33

5

85 8.6 0.455 0.725 99.28

6

85 8.9 0.446 0.793 99.21

7

85 9.3 0.588 0.914 99.09

8

85 8.8 0.504 0.826 99.17

9

85 8.5 0.523 0.878 99.12

10 85 8.2 0.630 1.05 98.95

Control 1 85 9.5 0.418 0.687 99.31

Control 2 85 9.5 0.371 0.642 99.36

Control 3 85 9.2 0.289 0.470 99.53

3M 8511, dry heat, 

3 cycles

Min Fil Eff: 99.09%

Max Fil Eff: 99.82%

1 85 7.6 0.169 0.295 99.71

2 85 7.4 0.194 0.455 99.55

3 85 7.6 0.171 0.252 99.75

4 85 6.9 0.234 0.482 99.52

5 85 7.6 0.171 0.356 99.64

6 85 7.5 0.104 0.206 99.79

7 85 7.6 0.111 0.189 99.81

8 85 7.7 0.115 0.310 99.69

9 85 8.1 0.081 0.185 99.82

10 85 7.6 0.795 0.913 99.09

Control 1 85 8.4 0.209 0.335 99.67

Control 2 85 8.3 0.053 0.166 99.83

Control 3 85 9.1 0.411 0.492 99.51
Table 2. Manikin Fit Evaluation – 3M

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, dry 

heat, 3 cycles

Static Advanced 

Medium 

Headform 

(Hanson Robotics)

11 107 184 145 138

12 200+ 200+ 200+ 200+

13 200+ 127 200+ 168

14 190 161 134 159

15 200+ 168 182 182

Control 4 200+ 200+ 200+ 200+

Control 5 200+ 200+ 200+ 200+

3M 8511, dry 

heat, 3 cycles

Static Advanced 

Medium 

Headform 

(Hanson Robotics)

11 200+ 200+ 200+ 200+

12 200+ 200+ 200+ 200+

13 200+ 200+ 200+ 200+

14 200+ 200+ 200+ 200+

15 200+ 200+ 200+ 200+

Control 4 200+ 200+ 200+ 200+

Control 5 200+ 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 3. Strap Integrity Evaluation – 3M 

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, dry heat, 3 cycles

1 2.797 2.543

2 2.704 2.666

3 2.729 2.589

Decontaminated Strap 

Average 2.743 2.599

Control 1 2.791 2.660

Control 2 2.793 2.712

Control Strap Average 2.792 2.686

% Change

((Deconned - Controls) / 

Controls)

-1.76% -3.24%

3M 8511, dry heat, 3 cycles

1 2.581 2.645

2 2.674 2.793

3 2.891 2.634

Decontaminated Strap 

Average 2.715 2.691

Control 1 2.813 2.856

Control 2 2.889 2.731

Control Strap Average 2.851 2.794

% Change

((Deconned - Controls) / 

Controls)

-4.77% -3.69%
Table 4. Filter Efficiency Evaluation – Halyard

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 

(%)

Halyard 62126, dry 

heat, 3 cycles

Min Fil Eff: 99.18%

Max Fil Eff: 99.78%

1

85 10.6 0.233 0.216 99.78

2

85 10.9 0.282 0.282 99.72

3

85 10.7 0.301 0.301 99.70

4

85 11.9 0.434 0.434 99.57

5

85 11.0 0.301 0.301 99.70

6

85 10.6 0.538 0.540 99.46

7

85 10.9 0.681 0.689 99.31

8

85 10.6 0.369 0.369 99.63

9

85 10.3 0.820 0.820 99.18

10 85 10.9 0.277 0.286 99.71

Control 1 85 12.0 0.296 0.296 99.70

Control 2 85 11.0 0.409 0.409 99.59

Control 3 85 12.1 0.718 0.718 99.28
Table 5. Manikin Fit Evaluation – Halyard

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

Halyard 62126, 

dry heat, 3 cycles

Static Advanced 

Large Headform 

(Lunar Studios)

11 200+ 200+ 200+ 200+

12 200+ 200+ 200+ 200+

13 200+ 200+ 200+ 200+

14 200+ 200+ 200+ 200+

15 200+ 200+ 200+ 200+

Control 4 200+ 200+ 200+ 200+

Control 5 200+ 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 6. Strap Integrity Evaluation – Halyard

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)

Halyard 62126, dry heat, 3 

cycles

1 2.294 2.341

2 2.249 2.316

3 2.195 2.301

Decontaminated Strap 

Average 2.246 2.319

Control 1 2.339 2.405

Control 2 2.359 2.390

Control Strap Average 2.349 2.398

% Change

((Deconned - Controls) / 

Controls)

-4.38% -3.29%