Does Microwaving Masks Disinfect Viruses?

Microwave time and power to kill HIV hepatitis viruses clean cover

With masks in short supply, many people are being forced to re-use masks. That means the idea of microwaving masks has gone from a crazy-sounding idea to a critically practical question.

Does Microwaving Masks Deactivate The Coronavirus?

Another reason this question is critical: Smart Air tests found that washing N95 masks with soap and water cut particle capture effectiveness by 21%. Other tests found that even just dipping in alcohol (no rubbing involved) harmed performance.

To get to the bottom of it, Smart Air was dumb enough to test it by actually microwaving masks! To start, let’s break this question down into two simpler questions.

WATCH: Can Microwaving Masks Disinfect them from Viruses?

1. Does Microwaving Deactivate Viruses?

First, let’s take a look at whether household microwaves can actually kill viruses (stern scientists out there are shouting “inactivate,” since viruses aren’t technically alive). Researchers in Germany tested whether microwaving syringes and cigarette filters could deactivate the viruses behind hepatitis C and HIV.

Microwaving cigarette filters and syringes to kill covid19 coronavirus

Why cigarettes and syringes? Because drug addicts often use cigarettes and syringes, and they can get infected through them.

Researchers contaminated cigarette filters and the plastic part of syringes with Hepatitis C or HIV. Then they microwaved them for 3 minutes at different power levels.

Microwave time and power to kill HIV hepatitis viruses clean

The results showed that microwaving at 360 watts for 3 minutes was enough to deactivate the vast bulk of the virus.

Microwaving for 3 minutes kill HIV and Hepatitis C viruses but not coronavirus

 

To be on the safe side, the researchers recommended microwaving at 600 watts for 2 minutes or longer. The good news is that most household microwaves on high can cook at 600 watts.
conclusion on microwaving items to kill and disinfect viruses

But What About Coronaviruses?

The researchers in Germany tested the effects of microwaving on Hepatitis C and HIV viruses, not coronaviruses. Although there isn’t research on microwaving Covid-19, scientists have tested this with human parainfluenza, an RNA virus similar to the coronavirus that infects humans.

These scientists put viruses on plastic petri dishes and microwaved them on high for 20 to 200 seconds.

The data showed that microwaving for 3 minutes was enough to deactivate polio and parainfluenza viruses.Microwaving parainfluenza for 3 minutes kills virus

What is ‘600W’, and Does My Microwave Meet the Spec?

The ‘600W’ the scientists used to zap viruses refers to the power of the microwave. You can think of this as the ‘Low’, ‘Medium’ and ‘High’ settings on your microwave. Most household microwaves on the ‘high’ have an output of 700-1200W, so it’s quite likely your microwave will meet the spec. To be doubly sure, you can check the sticker on the back of your microwave.

Microwave power for disinfecting viruses wattage

2. OK, But Does Microwaving Masks Harm Performance?

OK, tests showed that microwaving can disinfect viruses from materials, but in the case of masks, we need to know if it harms the performance of the mask. To test this, Smart Air’s chief engineer Paddy took a used 3M N95 mask, and commandeered the microwave in the Smart Air kitchen.

 

Microwave N95 mask to disinfect from coronavirus efficiency

One problem with microwaving N95 masks: Paddy had to remove all the nose bar and the metal clips. Obviously this isn’t ideal. After removing the metal bits from the mask, the N95 mask became pretty much unusable. If your mask contains metal parts, then you may well end up having to destroy it before it even gets into the microwave. However, the are some masks that don’t contain any metal parts, especially many of the DIY masks that people are using right now.

Homemade DIY cotton mask tests testing how long you can use them for

To test the effect of microwaving, Paddy microwaved the 3M N95 mask on high for 3 minutes.

Put mask in microwave to kill coronavirus Covid19 virus

 

After about 2 minutes, the microwave started smelling. Not wanting to give up, Paddy persevered!

After 3 minutes in the microwave and then waiting for the mask to cool down, Paddy took a Met One GT-521, and tested how well the mask was able to capture 0.3 micron particles. This particle size is important to test because it’s typically the most difficult size to capture.

Paper towel test at capturing virus-sized particles

Read more: How effective paper towel is for making DIY masks.

Surprisingly, microwaving the mask did not harm the mask’s filtration effectiveness.

Microwaving Masks Does Not Harm Performance

If anything, microwaving slightly increased particle capture.

One Good Reason NOT to Start Microwaving Masks

Microwaving masks is dangerous. For one, microwaving can melt the material. What’s more, The Guardian reported that a man in the UK started a fire when he put a dishcloth in the microwave to sanitize it.

Microwaving Masks Dangerous

Bottom Line: Microwaving Masks to Deactivate Viruses

Tests find that microwaving contaminated objects at 600 watts for 3 minutes deactivates viruses. However, microwaving masks isn’t recommended if it requires removing metal parts. Microwaving masks may also cause masks to melt or even catch on fire, so it is dangerous!

Instead, there are other ways of disinfecting masks without creating a fire hazard.

Read more: This data-backed method reliably disinfects masks without harming performance.

Disinfect N95 mask wash alcohol viruses

P.S. How exactly does microwaving deactivate viruses?

In their report, the German scientists explained that temperatures of 56–60° C are enough to inactivate Hepatitis C viruses. Coming soon: How hot do you have to heat things up to inactivate Covid-19?


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Bairbre Matthews

Hi Paddy
I have made cotton face masks with removable pouch for hepafilter and removable moldable nose wire.
If I remove both of these is cotton safe to microwave?

Liz - Smart Air

Hi Bairbre, Liz here from Smart Air. Cotton should be safe to microwave, just make sure there is no rubber or metal accessaries attached when you heat it up in the microwave.

Darlene Herman

Dry the mask means leave outside to air & dry I assume. Should it be in the sun or is shade the 3 days OK?

Liz - Smart Air

Hi Darlene, Liz here from Smart Air. I would suggest to leave it under the sun since UV light also helps to disinfect the virus, check out this article for more details:https://smartairfilters.com/en/blog/uv-light-disinfects-masks/. But leaving it in shade would do too!

Filmteknik

Regarding microwaving masks please be aware that most microwave ovens do not throttle. A few do but most do varying cooking levels by cycling the time the oven is actually on. When it’s cycled on, it’s at full power.

One should remove the metal nose piece and microwave the mask and straps alone. Disinfect the metal strip by wiping with alcohol, bleach water, or sanitizer. Or just wash with soap and water. It should be dry and wiped clear of any aloe from sanitizer. Then glue it back to the mask where it came off.

Jackie Thomas

you didn’t mention UVC for cleaning. I have read that it will deactivate CV-19 in mask, but no proof.

pranab kumar datta

I have microwaved paper?? Surgical musk with metal nose bridge for 30 seconds.no spark no remarkable heating ,then sprayed little hand sanitizer and repeated thinking if not microwave ,heat would kill sorry deactivate the prince of Wuhan .i am yet to get a ventiator allocation !