Microwave ovens and common viruses

[jberryhill]

This publication addresses using a standard microwave oven (Sharp R-772(W)M - 900 Watts) to destroy several types of virus:

Infectious bronchitis (IBV)

Avian pneumovirus (APV)

Newcastle disease virus (NDV)

Influenza virus (AIV)

https://www.tandfonline.com/doi/full/10.1080/0307945042000205874

Replicate swabs were dipped in each virus suspension and allowed to dry. They were then returned to their sheaths without sealing and placed either in the autoclave or microwave oven. Six swabs each were treated at intervals of 5, 60, 120, 180 or 240 sec.

...

Microwave treatment from as little as 5 sec was effective in eliminating virus infectivity for APV, IBV and NDV, but 20 sec was needed for AIV.

...

The results obtained from the experiments reported here showed that autoclave treatment using the standard conditions was sufficient to kill APV, IBV, NDV and AIV, which was to be expected. However, it was also shown that very short exposure to a domestic microwave was equally effective in inactivating these viruses. Despite this, both types of treatment allowed the survival of nucleic acids of APV and IBV so they could be detected by RT-PCR. It seems probable that PCR products of NDV and AIV would also have been detectable under these conditions, but that was not the purpose of the work.

Microwave treatment, in particular, has the advantage of convenience, since we have shown that inactivation can be done with a simple domestic microwave oven and the treatment time required is very short. Furthermore, this treatment does not involve the use of unpleasant inactivating fluids, so that the samples can be dispatched dry, with consequently simpler and safer packaging.

[frazzled]

1. So are we supposed to stick our heads in the microwave?

Don’t be trying to stick your canned goods in: a good explosion will ensue.

[NutmegYankee]

3. For Trump supporters, I actively encourage it. nt

[IADEMO2004]

29. Yes. Slam the door hard enough to completely close the door.

[jberryhill]

5. There are many things one should not put into a microwave

[panader0]

7. Don't try to cure gonorrhea with a microwave.

[lagomorph777]

15. Ow my balls!

[jberryhill]

16. That's how Randy Marsh got cancer

[smirkymonkey]

51. That was the first thing I thought of when reading your OP!

[lagomorph777]

17. The article is about specimen preparation; seems like a promising safety measure

that won't screw up the test result too much

[jberryhill]

23. Yeah

The idea was to inactivate the viruses and leave the DNA intact for sequencing.

There is also some literature linked elsewhere in the thread about using microwaves as a makeshift method to reduce HIV transmission among IV drug users.

[still_one]

33. True. Metal and things that melt

[Proud Liberal Dem]

26. And get yourself a tan

Dare to be stupid

[Historic NY]

2. I wash my kitchen sponges in the dishwasher and disinfect them with a 10+ sec microwave..

you can do other items towels, washcloths,

[budkin]

61. Same!

Works great.

[hlthe2b]

4. There is evidence microwaving inactivates Hep A and C viruses--important because

while Hep C is an enveloped RNA virus (SARS-COV-2, cause of COVID-19 disease is as well), Hep A is a NON-ENVELOPED RNA virus. The non-enveloped viruses are much more difficult to inactivate. So, both lab and epidemiological data suggesting microwave can disrupt HepA bodes well that this coronavirus can be as well.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5114683/
https://www.jwatch.org/jw199009110000002/1990/09/11/microwaving-may-inactivate-hepatitis-virus

[cayugafalls]

6. Perhaps this would work on masks?

We have a few masks left from when my mom was battling cancer and have used one for my wife and I when we went shopping.

It would be nice if we could bring them home in a plastic bag and disinfect them to use again as we don't really have that many and it gives me some comfort to wear them even though people say they are not necessary.

Thanks for the post...

[jberryhill]

9. I would not recommend microwaving anything that has metal parts

https://www.livescience.com/sanitizing-medical-masks-for-reuse-coronavirus.html

Referring to a paper published in the journal Annals of Occupational Hygiene in 2009, among others, the researchers compared and contrasted these different methods for sterilizing N95 masks, many of which were ineffective:

Heat in an oven for 30 minutes at 158 degrees Fahrenheit (70 degrees Celsius)
Use ultraviolet light for 30 minutes
Soak the mask in 75% ethyl alcohol, then let it dry
Clean the mask with liquid or vapor hydrogen peroxide
Clean the mask with bleach
Steam the mask with hot vapor from boiling water
Microwave the mask
Use extreme heat in an oven or autoclave
Soak in soap and water

"To be useful, a decontamination method must eliminate the viral threat, be harmless to end-users and retain respirator integrity," they wrote.

All of the methods used were believed effective for destroying coronaviruses, they wrote, but not all of them were good ideas.

"DO NOT use alcohol and chlorine [bleach]-based disinfection methods," they wrote. "These will remove the static charge in the microfibers in N95 facial masks, reducing filtration efficiency. In addition, chlorine also retains gas after de-contamination, and these fumes may be harmful."

Microwaves tended to melt the masks and render them useless.

[ProfessorGAC]

13. There's A Typo In Your Paste

There's a "1" missing in the oven method. 70C is 158F, not 58.

[cayugafalls]

20. Thank you. I guess we can try to recycle them if we run low.

Perhaps, letting them sit outside in sunlight for a day and then not using them for at least a week.

Well it was a thought...

Thanks again.

[frazzled]

39. If you have a clothes steamer

That would work; the water boils to produce steam. You can steam upholstery, nonwashable items like throw pillows, etc. I know it kills bacteria, I hope viruses too.

[Meowmee]

47. Steam kills just about everything in seconds

It kills c difficile which is usually only vulnerable to a certain bleach concentration if the surface is kept wet for five minutes.

[frazzled]

48. I was thinking of getting a substantial steam cleaner 4 or 5 months ago

Before all this broke. To clean floors and such, and to avoid chemical products. But I put it off. Now I’m just happy to have found the little hand-held clothes steamer that I hadn’t really used in years!

[Meowmee]

50. I gave two away stupidly

to save space and because it was harder for me to use them vs other things. When one of my cats had c difficile I bought a steam mop and then planned to get another bigger one that can steam anything. I finally did, it just arrived today and I am disinfecting the packaging etc. I am going to use it to steam all packages etc. All the fumes from the wipes and stuff are making my asthma and allergies even worse, and they are soaking through the gloves I use. I just steamed all the floors with the steam mop yesterday but this will be much faster and easier since it doesn’t have to be refilled so often. It’s the same one I had before 😹

[Kitchari]

60. Can you name

The one you recommend?

[Meowmee]

62. I got a Wagner again

Last edited Fri Mar 27, 2020, 01:17 AM - Edit history (1)

Just used it and it is very good so far, I think they improved it a bit because it seems easier to push the wand to clean floors. My cats are scared of it though, lol. I had fun steaming all the floors etc. again and things like bathrooms faucets door handles are much faster to do and no fumes. It has several attachments, even one for removing wallpaper which I actually have some I have been procrastinating about removing.

* the only drawback so far and I think this may not have been true for the older is that the cord is very short, but the wand tube is longer- I had to plug it to a long extension cord.

[Meowmee]

64. Well the wagner stopped working after two days. So I am returning it. I ordered a karcher nt

[Kitchari]

67. Darn

Thanks for the update. What a hassle!

[Meowmee]

68. Yep, especially in the midst of this but I am excited to get the karcher, hope it gets here fast.

Yw 😊

[58Sunliner]

56. Instead of an oven use a dryer with a dryer shelf. Infrared thermometer reader is handy.

In this materials science study of N95 face masks, two disinfection methods which do not reduce the filtration efficiency of the meltblown layer after an appreciable number of treatment cycles were found:
•Method 1: 75°C Hot Air (30 mins) for 20 cycles•
Method 2: UV (254 nm, 8W, 30 min) for 10 cycles Steam treatment causes filtration efficiency to drop to ~85% after 5 cycles, and ~80% after 10 cycles.
https://stanfordmedicine.app.box.com/v/covid19-PPE-1-2

[hardluck]

63. Thank you!

Very informative link.

[bamagal62]

8. Many masks have some metal

at the nose to help keep it in place. I imagine that would be a problem in a microwave.

[rzemanfl]

12. You imagine correctly IMHO. Now I have to decide whether I need to wash socks. n/t

[jberryhill]

18. I try not to microwave my underwear and shirts in the same load

[aikoaiko]

10. Baking masks at 160* was what I heard on news

But I haven't had a chance to verify with a specific source.

FWIW

[Dem2]

11. Could I briefly microwave the blackberries I bought today?

Versus treating them with a dilute chlorine solution? If so, hopefully putting them back into the fridge to cool would have them still palatable maybe.

[jberryhill]

14. I would not draw too many conclusions from something you saw posted on the internet

[Dem2]

21. Hey, one can only ask...

I was going to google it and saw this post, was hoping someone had some info.

I REALLY want to eat those fresh blackberries, but because the container has openings, I'm surely not going to do so without treating them somehow. Either that or I just look at them lovingly and toss them after a few days

[jberryhill]

25. I like the idea of baking them into a cobbler

In general, fresh fruits and vegetables are hard to "clean" effectively.

But since the virus can be killed by hot temperatures (easily below boiling) vegetable soups and stews, and various cooked fruit recipes, might be worth exploring.

[Dem2]

41. If only I knew how to make a cobbler

lol

[csziggy]

45. Cobblers are really easy to make

Blackberry Cobbler

Ingredients

1/2 stick butter, melted, plus more for greasing pan

1 1/4 cups plus 2 tablespoons sugar

1 cup self-rising flour

1 cup whole milk

2 cups fresh (or frozen) blackberries

Whipped cream and/or ice cream, for serving

Directions

Preheat the oven to 350 degrees F. Grease a 3-quart baking dish with butter.
In a medium bowl, whisk 1 cup sugar with the flour and milk. Whisk in the melted butter.
Rinse the blackberries and pat them dry. Pour the batter into the baking dish. Sprinkle the blackberries evenly over the top of the batter. Sprinkle 1/4 cup sugar over the blackberries. Bake until golden brown and bubbly, about 1 hour. When 10 minutes of the cooking time remains, sprinkle the remaining 2 tablespoons sugar over the top. Top with whipped cream or ice cream . . . or both!

https://www.foodnetwork.com/recipes/ree-drummond/blackberry-cobbler-recipe-1925731

[Dem2]

46. Thanks!

I might just try it. Or a crisp which I do know how to make...

[Meowmee]

49. Pretty easy, I recommend a grain free topping or no topping and stevia or a less sugary sweetener

https://www.allrecipes.com/recipe/229088/apple-crisp-with-oat-topping/

https://www.bettycrocker.com/recipes/blackberry-cobbler/97b86fd2-7588-497b-866d-8a1bd8b2e491

[Ilsa]

22. I think if you baked them into a cobbler, it would be

safe for me to eat. I wouldn't mind testing it for you.

[Hortensis]

27. Dem2, try it with a few and pass it on.

[LunaSea]

19. Great post, thanks!

About UV, I know that the frequency of UVC is a disinfectant but I'm wondering about UVA (commonly emitted from "blacklight" lamps. Anyone have info on effectiveness of UVA?

[LunaSea]

24. answering my own questions..

https://www.trojanuv.com/uv-basics

[still_one]

28. Thanks jb. I suspect you can use it on masks to reuse

[jberryhill]

30. I have no idea

As noted above, masks have metal parts. Metal parts are going to get very hot, very fast.

[still_one]

32. If they contain metal you are right, can't be done. I have also heard UV can be used

[Disaffected]

52. Not necessarily:

Metal reflects microwaves (that's why they bounce around off the walls of the microwave oven until they are absorbed by what's being heated). When heating soup in a microwave, I always place a metal spoon in the soup bowl as it is a good conductor of heat and helps the liquid warm more evenly. The metal in the spoon in this case causes no issues because it is a solid chunk of metal that does not loop back on itself to form in effect an antenna or, spark gap. The spoon only gets as hot as the soup itself.

Now, something like a fork or crumpled foil or something forming a ring of metal such as a metal rim around a plate or bowl for example do not generally react well at all (you can get rapid arcing and melting of the metal) so avoid metal objects of similar geometry.

OK, I just had a look at an N95 mask I happened to have. There is a small strip of metal at the nose area designed to bend around the nose and provide a seal. This particular mask also has a plastic one-way valve in front.

I placed the mask in a 1000 Watt microwave set to high for increasing time intervals to see what happens:

15 seconds - slight warming of the metal and fabric; no appreciable warming of the plastic. No sparking or arcing.

30 seconds - as above but slightly greater warming. It appears the mask material is not a strong absorber of microwaves.

I then soaked the mask in water and placed in microwave for 15 seconds - the mask became very warm and began steaming (the water boiling off) but no apparent damage to the mask was evident.

I conclude that microwave sterilization of a mask, of that particular construction at least, might be a viable method (instead of running the microwave on high, maybe at half power and for a longer period of time?). YMMV...

[jberryhill]

53. Cool

Well, even if the microwaves were not effective, the heat from the steam is.

[Disaffected]

55. Yes,

as long as the water does not damage the filtering capability of the mask.

My experimental mask is dried out now and I can see no apparent change to the filter fabric but any changes might not be visible.

[GulfCoast66]

57. You can put a little metal in the microwave

If for a short time like 20 second.

When I was poor in college I routinely would put bulk popcorn in a used fast foot sack, staple it a 4-5 times and let it rip till the popcorn popped.

Never caused a problem.

[lpbk2713]

31. Aah ... Kleenex can be recycled.

Thanks.

[Hortensis]

34. No to combating gonorrhea, but yes to nuking the mail.

We've been wondering what might still be active on it, and that'll be the first stop in the house before opening. Maybe 45 seconds.

Thanks, Jberry, for the valuable post. Seems like social distancing should make nuking most underwear unnecessary.

And thanks everyone for the valuable discussion.

[jberryhill]

37. Well....

One might think about putting something from outside of the house into a device where you prepare your food.

Perhaps a better idea would be to put the mail into a container of some kind, and be sure that the mail has no enclosures like credit cards or metallic objects; if you are going to do that.

(as an aside, using a 1200W oven, I find that staples in catalogs render them marginally warmer, but do not start a fire)

[Hortensis]

43. Now, how'd you find that out? : ) We have second MW

that we'll dust off and use. Thanks.

[Siwsan]

35. So, maybe microwave snail mail?

I get so much 'junk' mail, I'm using a bag to grab it and then tossing it directly into the trash. However, I will be getting a tax refund and would hate to have that trigger my demise. I might just give it a blast.

[jberryhill]

38. I make no recommendation or warranty

[Alex4Martinez]

36. KR. Will use with paper masks and with cloth gardening gloves and anything else microwave friendly

I have some paper masks coming soon and can find some cloth gloves.

We all have a microwave, thanks for finding and sharing this info!

[videohead5]

40. Carry out foods

If anyone gets carry out foods it would not hurt to nuke it for 5 seconds.

[roamer65]

65. Nuke them till they steam.

That is a sure kill.

[Brother Buzz]

42. Would a microwave be a good candidate to disinfect your mail?

That is, if you're getting squirrelly about it because your mailman looks a little under the weather.

[jberryhill]

44. I do not know

I have been placing my mail directly from the box into a sealable plastic shoebox container, fumigating it with some bleach solution, and leaving it to sit for two days (and collecting the mail on a two day cycle).

If one were to microwave the mail, one would want to make sure that the mail was free of things like credit cards (the chips will catch fire) or metallic objects which can cause heat.

The other thing to think about, of course, is that you would then be putting your mail into a piece of equipment in which you prepare food. So you wouldn't want to just throw the mail into it, but you would want to use a clean bag or container of some kind.

Would it disinfect the mail? I don't know. It introduces a risk that an unknown object in your mail could catch fire. But between nuking your mail or not nuking your mail, it won't make it worse in terms of infection relative to doing nothing.

It's an interesting question.

The study above demonstrates a common household microwave oven to be effective against the viruses they tested.

[Disaffected]

54. I don't know either but

it sounds like a v good idea worth investigating (I've been spraying it with bleach solution). As you point out, avoid things like credit cards or metallic objects. And, don't leave it in too long as the paper may overheat.

I would be very surprised if it does not work - someone with the proper evaluation equipment should really take a look at it as it is not far fetched at all IMO that the mail could be a significant virus vector.

[Hermit-The-Prog]

59. Bleach removes ink from bills.

I use a disinfectant that is 1.25% sodium hypochlorite. It takes 5 minutes for it to do the job, according to the EPA list. Unfortunately, the ink on some bills doesn't last that long. My mail just sits in quarantine for a few days, now.

[GulfCoast66]

58. My microwave is a big part of my sanitation routine.

All grocery items in hard containers get an alcohol wipe. Paper or cardboard packages go in the microwave for 20-25 seconds.

Same with the morning news paper and mail.

Also, we are trying to support mom and pop restaurants by doing pick up 2-3 times a week although I cook almost every night normally. The food goes onto the plate and is microwaved till hot. Just make sure you disinfect anything the packages touched including your hands.

While things may have changed since the mid 80’s I learned in my microbiology class I that microwaves were brutal to all single cell organisms including virus which are not cellular at all. Would appreciate any research that shows a different result since then.

[roamer65]

66. The biggest disease carrier you can eliminate is paper currency.

Those notes go around and around and around.

Cotton fiber banknotes are a circulating Petri dish.

There is a reason that the Fed was quarantining US bank notes coming back from Asia. Same reason China is currently destroying old notes and replacing with fresh ones.