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Covid Advice #5 (05/04/2020):
Masks, Dryer Heat, Car Seat, Hot Weather

- from Dr. Dennis Fong -

1. MASKS - CLOTH, MEDICAL, N95's (revised 07/15/2020):

Of the three kinds of masks out there, which one should I use, cloth, medical, or N95?

All three protect both others and yourself far more than no mask at all - even a scarf or bandanna is better than nothing. So at least wear a mask.

Cloth Masks:
They will protect others decently enough, but far less than medical or N95. COVID spreads by saliva droplets that get sprayed out when people breath heavily, talk, cough or sneeze, and cloth masks can't completely block out such droplets. In the old days all doctors and nurses had were cloth makss but they were made of expensive special very tightly woven cloth and they were still significantly inferior to today's medical masks. I doubt such cloth is still being manufactured so the ones being sold today are even more inferior. Wear a cloth mask if you can't get anything else, but wear a medical mask if you can get one at all.

The Disposable, Typically Blue "Medical" Masks:
Also called nursing or dental masks, these are your "one-use, disposable masks". Often they are not sold under the name of medical masks, but they have the same technology, just their ability to resist a jet of liquid sprayed at it at certain psi (pounds per square inch) is at the lower tier of medical masks. Don't look down upon these masks just because they are cheap, because they have a specially engineered three layer system - cut one open and see for yourself. This system is not only nearly 100% effective at keepying your saliva droplets from spraying out, but also as good as medical (not industrial) N95's at keeping others' saliva droplets from getting in. That's why for the general public this is the mask to use. They are pretty available in the drugstores and on Amazon again so there's no reason not to wear one. These masks can be reused if you quarantine them for 3 days in a box. Do not wash them or use heat on them - that destroys the 3 layer system.

N95 Masks:
There's a lot of fake news on N95's. These are engineered quite differently and are designed to filter out very very fine particles. Most of what people have out there are industrial N95's, and industrial N95's don't have a coating on the outside to resist a jet of liquid sprayed at it, nor a coating on the inside to keep the moisture of your breath from soaking through. Thus they can't resist liquid saliva droplets from a cough or sneeze close by, and the moisture of your breath can soak through and create a conduit for the virus. Medical N95's have both coatings inside and outside, and are designed for resisting liquid aerosol from the nose, mouth, throat and lungs, much finer than just saliva droplets. Aerosol is what is generated with many hospital procedures, especially the ICU. An example is people being on ventilators. So medical N95's are what doctors and nurses need in order to care for COVID patients. Since the general public's problem is saliva droplets and not aerosols, these are not necessary for the general public. And to be safe, we need to wear a blue disposable mask over an industrial N95 -- you might as well just wear a blue disposable mask

Don't know whether you have an industrial N95 or a medical N95? Just run some water on it. If the water soaks in it's industrial - wear a blue mask over it, or just wear a blue mask period. You will notice that when you run water over the blue mask the water will bead up and run off.

Warnings on N95's:
- One warning: there are reports that the smaller lungs of pre-adolescent children can't generate neough power to draw enough oxygen in or expel enough carbon dioxide out through an N95, especially when active, so I don't recommend N95's for small children.
- Another warning: N95's have to be the right size; they can't be too big or too small. This is especially a problem with women who may have a petite face and men who may have a big broad face.
- A third warning: unlike medical N95's, industrial N95's that you may have found in your garage from Uncle Joe's fire a couple of years ago do not protect against larger droplets, like what you may get if someone sneezes or coughs within a few feet, because they lack that moisture proof outer coating that medical N95's have. This is especially so if you are shorter than the person coughing or sneezing as the salvia droplets may be faling down but they still will have started high enough to land onto your mask. Stick to the much cheaper, and now widely available to the general public, medical masks. Moisture proof against saliva dropolets, that's what the outermost layer on a medical mask is for.


My N95 masks are substandard; shouldn't I wear cloth masks instead?

No, even a substandard N95 is better than cloth and if worn correctly as in my notes on N95's above, probably as good as a medical mask. From what I can gather, it's mainly just two things that make these N95's not meet U.S. government standards: either they let through one or two kinds of all the kinds of microspic particles that U.S. government standards require to be filtered out but some other countries don't, or they have ear loops that on some people may not be as tight as the rubber bands that U.S. government standards require. So if you don't have any medical masks at all but you have to go out, use even a substandard N95.

Again, N95's are not necessary for the general public; the general public's problem is droplets not aerosols.


Can I wash my masks in soap and water so I don't have to throw them away after one use?

No, you can't wash medical masks, that destroys the 3 layer system that blocks out droplets so effectively, but yes, since they are in short supply you can reuse them. The solution is quarantining. See my April 5 "Covid Advice #1" on quarantining things in general. Here is one way you can quarantine your masks:

- Get 3 boxes and mark one "Mondays & Thursdays", one "Tuesdays & Fridays", and one "Wednesdays, Saturdays, and Sundays".

- Depending on what day of the week you come home, you put your mask into the appropriate box.

- You need to quarantine a mask for 3 days, since Covid dies in 2 days on a mask but we do one more day to make sure. So the mask you put into the box on Monday you take out on Thursday for reuse; on Tuesday, take out Friday; and so on.

- Note: on Thursday, don't forget to take out the mask from Monday first, before you put in the Thursday mask for quarantine, or the now clean de-contaminated Monday one will get contaminated by being touched by the mask you've just dropped in and you'll have to wait the 3 days all over again.


Can I put things in the dryer and turn the heat to maximum to kill Covid?

I doubt it. Boiling will kill Covid right away, but you need 30 minutes at 160 degrees, and that's the maximum that old dryers are set to. You need a whole hour at 140 degrees, and that's the maximum that newer dryers are set to for safety reasons. Often though, even freshly bought dryers don't reach their maximum set temperatures, not to speak of a used one, like what you probably have at home right now.


My glasses fog up with goggles, what do I do?

Covid droplets infect you not only through your nose, but also through your eyes. Goggles sometimes cloud up glasses but face shields usually don't.

What's more, face shields protect your whole face. Also, face shields are far cheaper and they are quite available now on Amazon. Make sure after use to either disinfect them or quarantine them for 5 days.

Of course, you need a mask under the face shield. Here's how it should look.


On the way home, my clothes are contaminated from being in the store, so doesn't sitting on my car seat contaminate it?

Very good question and the answer is yes. Also, unless made of leather, car seats are hard to disinfect. So when going out cover your car seat with a fresh clean bedsheet. After you return home, that bedsheet is contaminated so throw it into the washer right away. You can also use a very big beach towel.


You said in the April 5 email to wear a hoodie and outer pants when I go out, but don't you think very soon the weather will be too hot for that?

Very good question, since the weather is warming up fast, and for those who are elderly or have underlying medical conditions, a heat stroke is possible if you get too hot. I would suggest two things:

- One, thin outer clothing over short sleeves and shorts, like a "lightweight hooded T shirt" (search the term on Amazon; $14 each I got a bunch for), a thin summer jacket with a hood, thin outer pants, etc.

- Two, if your car doesn't have air conditioning, put on and take off the hoodie and outer pants in the parking lot. After shopping, when you get to your car, take off the outer clothing and put them in a box in your trunk and of course, throw them into the washer when you get home.

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