Evaluation of Decontaminated N95 Respirators 

Date Tested: 6/3/2020 – 6/8/2020 

Respirator Model(s): 3M 8511 and Sperian N1105 

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: 10 cycles (Sperian N1105) and 20 cycles (3M 8511) 

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). 

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

evaluation. This included 15 respirators that were subjected to 10 cycles of the VPHP decontamination process, 

15 respirators subjected to 20 cycles, and an additional 8 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%. Two of the ten respirators measured 

efficiencies less 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. See Tables 2 and 5. 

Strap Integrity Results: No visual degradation of the straps was observed. The Sperian N1105 (10 cycles) 

showed increases in force for both the top and bottom straps, while the 3M 8511 (20 cycles) showed an 

increase in the top strap but virtually no change in the bottom strap. See Tables 3 and 6. 

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 - Sperian N1105

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 

(%)

Sperian N1105, 

VPHP, 10 Cycles

Min Fil Eff: 99.74%

Max Fil Eff: 99.88%

1

85 13.1 0.146 0.171 99.83

2

85 13.3 0.149 0.170 99.83

3

85 11.4 0.178 0.204 99.80

4

85 12.6 0.115 0.132 99.87

5

85 12.0 0.209 0.252 99.75

6

85 12.9 0.103 0.133 99.87

7

85 11.5 0.142 0.162 99.84

8

85 11.3 0.255 0.261 99.74

9

85 12.9 0.141 0.146 99.85

10 85 11.8 0.155 0.174 99.83

Control 1 85 11.8 0.145 0.166 99.83

Control 2 85 12.7 0.103 0.118 99.88
Table 2. Manikin Fit Evaluation - Sperian N1105

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

Sperian N1105, 

VPHP, 10 Cycles

Static Advanced 

Large Headform 

(Lunar Studios)

11 155 102 118 121

12 134 103 108 113

13 200+ 164 200+ 187

14 172 67 128 105

15 184 97 163 137

Control 3

131 86 120 109

Control 4

128 91 116 109

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 - Sperian N1105

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)

Sperian N1105, VPHP, 10

Cycles

1 1.744 1.780

2 1.730 1.616

3 1.888 1.904

Decontaminated Strap 

Average 1.787 1.767

Control 1 1.602 1.582

Control 2 1.631 1.798

Control Strap Average 1.617 1.690

% Change

((Deconned - Controls) / 

Controls)

10.5% 4.6%
Table 4. Filter Efficiency Evaluation - 3M 8511

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 8511, VPHP, 20

Cycles 

Min Fil Eff: 99.26% 

Max Fil Eff: 99.73% 

1

85 7.1 0.238 0.450 99.55

2

85 7.4 0.152 0.381 99.62

3

85 7.3 0.260 0.559 99.44

4

85 7.2 0.067 0.275 99.73

5

85 6.7 0.228 0.411 99.59

6

85 7.1 0.150 0.313 99.69

7

85 6.9 0.250 0.513 99.49

8

85 6.6 0.318 0.621 99.38

9

85 7.0 0.306 0.479 99.52

10 85 6.2 0.344 0.745 99.26

Control 1 85 6.4 0.165 0.541 99.46

Control 2 85 6.5 0.202 0.371 99.63
Table 5. Manikin Fit Evaluation - 3M 8511

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 8511, VPHP, 

20 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 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 6. Strap Integrity Evaluation - 3M 8511

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 8511, VPHP, 20 Cycles

1 3.079 2.894

2 3.608 3.091

3 3.705 3.132

Decontaminated Strap 

Average 3.464 3.039

Control 1 2.974 3.126

Control 2 2.894 2.945

Control Strap Average 2.934 3.036

% Change

((Deconned - Controls) / 

Controls)

18.1% 0.001%