Table IV.
Impacts of microwave- and heat-based decontamination strategies on physical traits and fit of N95 filtering facepiece respirators
| First author, year | Intervention parametersa | N95 models | Method of physical assessment | Physical traitsb | Odour | Fitc | ||
|---|---|---|---|---|---|---|---|---|
| Microwave | Bergman, 2010 | Power: 750 W/ft3 Time: 120 s Cycles: 3 Moisture: MGS |
3M 8000d 3M 8210d Moldex 2201d |
KC PFR95-174d 3M 1860d 3M 1870d |
Physical traits: visual inspection Odour: smelling the mask |
3M 1870: slight separation of inner foam nose cushion (N = 3/3) KC PFR95-174: strap melted after first cycle (N = 2/3) |
No odour reported | – |
| Bergman, 2011 | Power: 750 W/ft3 Time: 120 s Cycles: 3 Moisture: MGS |
3M 1860 3M 1870 KC PFR95-270 |
Physical traits: visual inspection Fit: author-modified OSHA protocol FF ≥100 = pass; faceseal leakage = 1/FF |
3M 1870: slight separation of inner foam nose cushion (same degree after all cycles) KC PFR95-270: strap melted after third cycle (N = 1/21) |
– | Fit test pass rate remained ≥90% for all models (N = 20) Mean faceseal leakage remained <1% for all models (N = 20), no significant difference |
||
| Fisher, 2011 | Power: 750 W/ft3 Time: 90 s Cycles: 1, 3 Moisture: MGS (steam bag) |
Cardinal Health 3M 8210 3M 1860 3M 1870 KC PFR95 Moldex 2200 |
Physical traits: water retention evaluated by comparing initial mask weight to weight after MGS treatment and drying in room conditions | Cardinal Health, 3M 8210, 3M 1860: significant water (≥8 g) retained after 60 min drying (N = 1) Moldex 2200, KC PFR95, 3M 1870: low water absorbency, dry (≤0.1 ± 0.1 g) within 30 min (N = 3) |
– | – | ||
| Heimbuch, 2011 | Power: 1250 We Time: 120 s Cycles: 1 Moisture: MGS |
3M 8000f 3M 8210f Moldex 1500f |
KC PFRf 3M 1860f 3M 1870f |
Physical traits: visual inspection | 3M 1870: slight separation of inner foam nose cushion | – | – | |
| Viscusi, 2007 | Power: 750 W/ft3 Time: 120 s, 240 s Cycles: 1 Moisture: Dry |
3M 8000d | Physical traits: visual and tactile inspection | 120s: no visible changes (N = 4/4) 240s: filter media melted at ends of metallic nosebands and formed holes |
– | – | ||
| Viscusi, 2009 | Power: 750 W/ft3 Time: 120 s Cycles: 1 Moisture: Dry |
3M 8000d 3M 8210d Moldex 2200d |
KC PFR95-270d 3M 1860d 3M 1870d |
Physical traits: visual and tactile inspection Odour: smelling the mask |
3M 1870: filtration media melted in areas adjacent to metallic nosebands (N = 3/3) | No odour reported | – | |
| Viscusi, 2011 |
Power: 750 W/ft3 Time: 120 s Cycles: 1 Moisture: MGS |
3M 8000 3M 8210 3M 1860 3M 1870 KC PFR 95-270 Moldex 2200 |
Physical changes: visual and tactile inspection (researchers) Odour: smelling the mask (researchers); blinded visual analogue scale and verbal reports (subjects) Fit: multiple-donning fit test using author-modified OSHA protocol. MDFF10 ≥100 = pass Comfort/donning ease: blinded visual analogue scale rating and verbal reports (subjects) |
Moldex 2200: strap breaks in both treatment (N = 1/21) and control (N = 2/22) 3M 1870: slight separation of inner foam nose cushion (N = NR); strap break in treatment (N = 1/21) but not control |
Quantitative – no significant difference Qualitative – researchers detected no odour changes. No treatment-based patterns in participants' verbal reports |
Fit: mean MDFF10 passed for all models (N = 20), no significant difference Comfort/donning ease: Quantitative – no significant differences Qualitative – no treatment-based patterns in participants' verbal reports |
||
| Heat | Bergman, 2010 | Temperature: 60°C Time: 30 min Cycles: 3 Moisture: MHI (80% RH) |
3M 8000d 3M 8210d Moldex 2201d |
KC PFR95-174d 3M 1860d 3M 1870d |
Physical traits: visual inspection Odour: smelling the mask |
3M 1870: slight separation of inner foam nose cushion (N = 3/3) | No odour reported | – |
| Bergman, 2011 | Temperature: 60°C Time: 15 min Cycles: 3 Moisture: MHI (80% RH) |
3M 1860 3M 1870 KC PFR95-270 |
Physical traits: visual inspection Fit: author-modified OSHA protocol. Fit factor ≥100 = pass; faceseal leakage = 1/FF |
3M 1870: slight separation of inner foam nose cushion (same amount after all cycles) | – | Fit test pass rate remained ≥90% for all models (N = 20) Mean faceseal leakage remained <1% for all models (N = 20), no significant difference |
||
| Fischer, 2020 | Temperature: 70°C Time: NR Cycles: 3 (2 h wear between each) Moisture: dry |
3M Aura 9211+/37193 | Fit: fit testing using official modified OSHA-standard protocol. Fit factor ≥100 = pass | – | – | 100% pass rate after 1st and 2nd cycles, 66% pass rate after 3rd cycle (N = 6) | ||
| Heimbuch 2011 | Temperature: 65°C Time: 30 min Cycles: 1 Moisture: MHI (85% RH) |
3M 8000f 3M 8210f Moldex 1500f |
KC PFRf 3M 1860f 3M 1870f |
Physical traits: visual inspection | No significant changes | – | – | |
| Kumar, 2020 | Temperature: 121°C Time: 15 min at peak temp Cycles: 1, 3, 5, 10 Moisture: Steam (AC) Pressure: NR | 3M 1860 3M Aura 1870 3M Vflex 1804S AOSafety 1054S |
Physical traits: visual and tactile inspection Fit: normal and deep breathing tests only; Fit factor ≥100 = pass |
3M Vflex 1804S: mild bleeding of ink label after 1 cycle (N = 1/1) | – | 3M 1860: passed after 1 cycle (N = 1), failed after subsequent cycles All other models: passed after all cycles (N = 1) |
||
| Lin, 2017 | Temperature: 149–164°CTime: 3 minCycles: 1Moisture: Dry | 3M 8210 | Physical traits: visual and tactile inspection | No changes reported | – | – | ||
| Temperature: 121°C Time: 15 min Cycles: 1 Moisture: Steam (AC) Pressure: 1.06 kg/cm2 |
3M 8210 | Physical traits: visual and tactile inspection | Folds of inner/outer filter supports. Outer layers of masks were deformed, shrunken, and stiff with no remarkable mottle | – | – | |||
| Viscusi, 2007 | Temperature: 80°C and 160°C Time: 60 min Cycles: 1 Moisture: Dry |
3M 8000d |
Physical traits: visual and tactile inspection |
80°C: No significant changes (N = 4/4) 160°C: Masks melted and unusable after 22 min |
– |
– |
||
| Temperature: 121°C Time: 15 min and 30 min Cycles: 1 Moisture: Steam (AC) Pressure: 1.05 kg/cm2 |
3M 8000d | Physical changes: visual and tactile inspection | Masks deformed, shrunken, stiff, and mottled at both durations | – | – | |||
| Viscusi, 2009 | Temperature: 80°C, 90°C, 100°C, 110°C, 120°C Time: 60 min Cycles: 1 Moisture: dry |
3M 8000d 3M 8210d Moldex 2200d |
KC PFR95-270d 3M 1860d 3M 1870d |
Physical traits: visual and tactile inspection Odour: smelling the mask |
KC PFR95-270 samples at 100°C, 110°C, and 120°C: inner moisture barrier melted into the filtration media (N = 1/3, 2/3, 2/3) | No odour reported | – | |
| Viscusi, 2011 | Temperature: 60°C Time: 30 min Cycles: 1 Moisture: MHI (80% RH) |
3M8000 3M8210 3M1860 3M1870 KC PFR 95-270 Moldex 2200 |
Physical changes: visual and tactile inspection (researchers) Odour: smelling the mask (researchers); blinded visual analogue scale and verbal reports (subjects) Fit: multiple-donning fit test using author-modified OSHA-protocol. MDFF10 ≥100 = pass. Comfort/donning ease: blinded visual analogue scale rating and verbal reports (subjects) |
3M 1870: slight separation of inner foam nose cushion Moldex 2200: strap breaks in both treatment (N = 3/23) and control (N = 2/22) |
Quantitative – 3M 1860 had significantly increased odour (+5.94 out of 100); no other significant differences Qualitative – researchers detected no odour changes. No treatment-based patterns in participants' verbal reports |
Fit: Mean MDFF10 passed for all models (N = 20), though 3M 8210 and Moldex 2200 had significant reductions in MDFF10 (-29 and -59, respectively) Comfort/donning ease: Quantitative – no significant differences Qualitative – no treatment-based patterns in participants' verbal reports |
||
AC, autoclave; FF, fit factor; KC, Kimberly–Clark; MDFF10, multi-donning fit factor; MGS, microwave-generated steam; MHI, moist heat incubation; OSHA, Occupational Safety and Health Administration; RH, relative humidity;–, outcome not assessed.
a
Room pressure unless otherwise specified. If both manufacturer-rated and experimentally-determined microwave power were provided, the experimental value is reported here.
b
Where replicate numbers are provided as N = x/y, x is the number of replicates per model in which the physical change was observed and y is the total number of replicates per model; absence of N values in the table indicates that replicate numbers were not reported for the observation.
c
N values represent numbers of replicates that underwent fit testing for each model.
d
Mask models were anonymized in article. Model names were obtained by e-mail from R. Shaffer in April 2020.
e
Power units per volume not specified.
f
Mask models were anonymized in article. Model names were obtained by e-mail from B. Heimbuch in April 2020.