Best practice is to use new N95s. Decontamination does not solve the PPE shortage crisis, and is an emergency practice to beconsidered during the COVID-19 pandemic. Efficacy and safety of N95 decontamination has not been fully characterized.

COVID N95
DECON &REUSEHEAT &HUMIDITY
See Technical Report at
n95decon.org/heat

CORONAVIRUS INACTIVATION
70°C dry heat for 60min inactivated
SARS-CoV-2 on N95 under lab
conditions 1

N95 MASK INTEGRITY*

50–85% humidity enhances
inactivation of flu virus (non-CoV) onN95 and metal 2–4
Real-world conditions (e.g. saliva,mucus droplets) may require higher
temperature, humidity, or longer time.
SARS-CoV-2 NOT inactivated by 70°C
dry heat for 30min (on N95) and60min (on metal)1
Method does NOT inactivate allbacterial or mold spores on N95 5

Several 3M N95 models (1860, 8210,8210+) keep fit and filtration for
multiple 30min cycles at 70–85°C and>50% humidity 6,7Many models (e.g., 3M 8200, 3M 8511)
keep fit performance for multiple
30min cycles at 75°C dry heat 8,9Each N95 model responds differently
to heat; many have not been tested
with the heating conditions above 1,10
Repeated thermal cycles may damage
N95 fit and filtration 1,10,11* ≥ 3-log inactivation

KEY CONSIDERATIONSRISKSTemperature and humidity must be calibrated andmonitored; heating devices can be highly variable

Heat inactivation is highly sensitive to temperature,humidity, time, surface, and co-contaminants

N95 must be isolated and returned to original user

N95 fit and filtration may be damaged if thetemperature is too high or after multiple cycles

User seal check must be performed before each reuse
Each don/doff can reduce N95 fit; some models fit
unacceptably after 5 don/doff cycles 12

IMPLEMENTATION

N95 will NOT be sterilized by the heat & humidity
treatments listed above
13

CDC released guidance on heat+humidity for N95 decontamination
Many devices can maintain 70–80°C, 50–85% humidity (warmingcabinets, water baths, autoclaves, ovens)

CONCLUSION

Method has not been validated in an FDA-approved process

Heat and humidity for N95 decontamination requires further investigation for inactivation of SARS-CoV-2. Its use should beevaluated by relevant authorities. This is a low-cost technique that could be easy to implement in a wide range of settings. However,excessive heating or multiple thermal cycles may damage N95 fit and filtration. Moreover, this approach will NOT protect against all
bacterial and mold co-infection risks. If risks are mitigated, this protocol merits future FDA feasibility studies.

SUPPORTING RESEARCH** = not peer-reviewed[1**] Fischer et al., 2020; [2] Bergman et al., 2010; [3] Lore et al. 2012; [4] McDevitt et al., 2010; [5] Rodriguez-Palacios & LeJeune,
2011; [6**] Anderegg et al., 2020; [7**] Massey et al., 2020; [8**] Price et al., 2020; [9] Viscusi et al., 2009; [10] Viscusi et al.,2011; [11**] 3M, 2020; [12] Bergman et al., 2012; [13] CDC, 2020
The Content provided by N95DECON is for INFORMATIONAL PURPOSES ONLY and DOES NOT CONSTITUTE THE
PROVIDING OF MEDICAL ADVICE and IS NOT INTENDED TO BE A SUBSTITUTE FOR INDEPENDENT PROFESSIONALMEDICAL JUDGMENT, ADVICE, DIAGNOSIS, OR TREATMENT. Use or reliance on any Content provided by N95DECON isSOLELY AT YOUR OWN RISK. A link to the full N95DECON disclaimer can be found at https://www.n95decon.org/disclaimer.

v2.0 (April 23, 2020)www.n95decon.org

Best practice is to use new N95s. Decontamination does not solve the PPE shortage crisis, and is an emergency practice to beconsidered during the COVID-19 pandemic. Efficacy and safety of N95 decontamination has not been fully characterized.

COVID N95
DECON &REUSEHEATRELATED
CONCERNSUNPROVEN METHODS

Autoclave

MicrowaveGenerated
SteamStandard autoclave cycle (121°C steam, 15 min) inactivates SARS1
CoV-2 on N95
Autoclave is an accepted means of sterilization in hospital setting
Many pleated N95 models (3M 1870,1804S, 1862+, 9211; Aearo1054S) pass quantitative fit test for 5 autoclave cycles 1,2Common molded N95 models (3M 1860, 8210, 8000) known tofail after 1–2 cycles of autoclave treatment 1,3
There are few studies on N95 filtration efficiency after autoclave
treatment 2,4
1
Different N95 models may respond differently to autoclave cycle
2 minutes above water reservoir in 1250 W microwave inactivates
3,5
H1N1 and H5N1 flu (non-coronavirus) on N95
No data on MGS inactivation of coronaviruses on N95
Most common N95 models shown to withstand at least one 2-min
MGS treatment, several models withstand up to 3 cycles 6–9
10
Possibility of N95 damage beyond three cycles
Few studies on N95 durability under more than one repeateddecontamination cycle
11
Some N95 models destroyed by 2-min microwave without steam
Metal components of N95 may present sparking hazard

UNSUITABLE METHODSHome OvenSUPPORTING RESEARCH

Bringing potentially biohazardous materials home is highly
dangerous and carries significant contamination risk** = not peer-reviewed[1**] Kumar et al., 2020; [2] van Straten et al., 2020; [3] Heimbuch et al., 2011; [4] Viscusi et al., 2007; [5] Lore et al., 2012; [6] Bergmanet al., 2010; [7] Bergman et al., 2011; [8] Viscusi et al., 2011; [9] Fisher et al., 2011; [10**] Liao et al., 2020; [11] Viscusi et al., 2009
The Content provided by N95DECON is for INFORMATIONAL PURPOSES ONLY and DOES NOT CONSTITUTE THEPROVIDING OF MEDICAL ADVICE and IS NOT INTENDED TO BE A SUBSTITUTE FOR INDEPENDENT PROFESSIONALMEDICAL JUDGMENT, ADVICE, DIAGNOSIS, OR TREATMENT. Use or reliance on any Content provided by
N95DECON is SOLELY AT YOUR OWN RISK. A link to the full N95DECON disclaimer can be found athttps://www.n95decon.org/disclaimer.

v1.0 (April 23, 2020)www.n95decon.org