COVID COVID-19 Coronavirus Containment Efforts

[anorlunda]

It's the lack of will of the federal government to implement such a process.

I'm an engineer. I want to see requirements before design and design before implementation. I've been watching and listening, and I've yet to hear a straight answer to the question, "How much testing is enough?"

Globally, the upper limit is of the order of 7 billion tests per day. Is that too much? Then state the requirement. How much is enough? Any answer needs to be accepted nearly everywhere to be useful.

I am most frustrated with journalists who fail to ask "How much is enough?" in press conferences where testing is discussed.

 

[bob012345]

I'm an engineer. I want to see requirements before design and design before implementation. I've been watching and listening, and I've yet to hear a straight answer to the question, "How much testing is enough?"

Globally, the upper limit is of the order of 7 billion tests per day. Is that too much? Then state the requirement. How much is enough? Any answer needs to be accepted nearly everywhere to be useful.

I am most frustrated with journalists who fail to ask "How much is enough?" in press conferences where testing is discussed.

Journalists don't care about that question. They care about making political statements and the testing issue has become a hammer to make political statements. What Dr. Birx said was reasonable. Enough testing is what is needed to handle any major local outbreak as the economy slowly opens up which she and Fauci expressed confidence that we have that capability now.

 

[Vanadium 50]

I'm an engineer. I want to see requirements before design and design before implementation

That's adorable! "I'll know it when I see it" is a more typical spec for me.

The reason you don't see a spec on testing is that the goals of testing are unclear. One thing you might want to do is have wide testing to statistically monitor the spread of the disease. Another is that you might want to use it for diagnostic purposes. A third is you might want to use it for is to identify and monitor individuals who may be exposed. (And there's also the "brickbat one can use against one's opponents" mentioned before)

These all have different requirements. For example, if I am using it to test individuals, I want the false positive/negative rate to be small. If I am using it statistically, I want the false positive/negative rate to be well-known (small is nice too). If I am testing millions, it needs to be quick, cheap and easy in a way that it doesn't if I am testing thousands. And so on.

 

[bob012345]

Look beyond the borders. If one country can test 5% of its population, why does another one with a similar economic situation struggle testing 1%?

Define similar. Similar size? Similar GDP but different population? Is the metric per capita? What tests are being used and how much do they cost? Are they vastly different in complexity? 1% of 330 million is a lot harder than 5% of 3 million. Even the number of tests can be defined differently in different countries.

https://ourworldindata.org/coronavirus-testing

As I understand, the in the U.S., the C.D.C. developed our test. The test was complex and cumbersome, and they only allowed certain state labs to use it despite requests from hundreds of private labs to help until the feds encouraged cooperation . But now, the cumulative tests in the U.S. per 1000 is 24.5 on par with many European nations and ahead of some. Our rolling three day average of new tests is about 1 per 1000 which also is on par with most of the world.

 

[bob012345]

It's not a lack of appreciation for the complexity of the problem. It's the lack of will of the federal government to implement such a process.

If you mean the slow response of the C.D.C. and their refusing to allow private labs to help develop and administer tests, yes.

 

[kyphysics]

QUESTIONS ON COVID-ASYMPTOMATICS

i.) Do we have any data on whether the elderly (let's say 65+) can be asymptomatic, while testing case positive, and essentially not have any negative effects felt from the virus?

ii.) Do we have any data and whether those with pre-existing conditions (say heart disease or diabetes, etc.) can be asymptomatic, while testing case positive, and essentially not have any negative effects felt from the virus?

Or, do ALL elderly and/or all those with pre-existing conditions ALWAYS GET symptoms and/or complications?

Thanks!

 

[Dullard]

Add 'time travel' to the virus' list of capabilities. As it tuns out, several hundred people in FL went to the hospital in January/February (been waiting for this story, because I'm pretty sure that I [and my whole family] had it in late December) with a severe respiratory ailment. Test of blood samples (taken then) are positive for Covid 19.

https://www.miamiherald.com/news/state/florida/article242480931.html

 

[kadiot]

Hi. Wife is buying these masks from Lazada. Do you think PM2.5 masks protect against Covid-19?

3 layers with respirators

5 layers with respirators

I would greatly appreciate any response. Thank you.

 

[collinsmark]

New Physics Girl video discussing epidemiology, symptoms, and science in the wake of a pandemic.

 

[vela]

Enough testing is what is needed to handle any major local outbreak as the economy slowly opens up which she and Fauci expressed confidence that we have that capability now.

Do you have a link to a report of this claim? I couldn't find anything. I did, however, run across an article published 12 days ago, which reported that Fauci said he thought the US needed to double the rate of testing. He said he thought we could get there, but it wasn't what was happening at the time.

 

[bob012345]

Add 'time travel' to the virus' list of capabilities. As it turns out, several hundred people in FL went to the hospital in January/February (been waiting for this story, because I'm pretty sure that I [and my whole family] had it in late December) with a severe respiratory ailment. Test of blood samples (taken then) are positive for Covid 19.

https://www.miamiherald.com/news/state/florida/article242480931.html

We already knew that the virus crossed from Asia to the West Coast and from Europe over to NYC well before cases were known. It isn't much of a surprise that people in Florida were exposed also. Probably many other places as it was confused with flu early on.

 

[PeroK]

Thinking specifically but not exclusively about the UK, does anyone have a reliable study of how the recent new infections are happening? We're still at 6,000 or so a day. Do we know why we have this number?

 

[PAllen]

Thinking specifically but not exclusively about the UK, does anyone have a reliable study of how the recent new infections are happening? We're still at 6,000 or so a day. Do we know why we have this number?

This is the big question my wife and I keep discussing. If only we had enough tracking to know where and how most new cases originate, we could have targeted interventions that are similar in effectiveness to full lockdown, but with much less economic cost.

 

[anorlunda]

Do you think PM2.5 masks protect against Covid-19?

Protect who? The wearer or other people?

 

[kadiot]

Protect who? The wearer or other people?

Primarily the wearer. Protect both is better, of course.

 

[bob012345]

Do you have a link to a report of this claim? I couldn't find anything. I did, however, run across an article published 12 days ago, which reported that Fauci said he thought the US needed to double the rate of testing. He said he thought we could get there, but it wasn't what was happening at the time.

I watched Dr. Birx explain that during the rollout of the metrics regarding the opening up of the economy in phases during the Task Force briefings.

 

[atyy]

QUESTIONS ON COVID-ASYMPTOMATICS

i.) Do we have any data on whether the elderly (let's say 65+) can be asymptomatic, while testing case positive, and essentially not have any negative effects felt from the virus?

ii.) Do we have any data and whether those with pre-existing conditions (say heart disease or diabetes, etc.) can be asymptomatic, while testing case positive, and essentially not have any negative effects felt from the virus?

Or, do ALL elderly and/or all those with pre-existing conditions ALWAYS GET symptoms and/or complications?

Thanks!

Seniors can be asymptomatic - no noticeable change in symptoms from onset of infection to the end of infection. In some studies, seniors with chronic cough that did not noticeably change were considered asymptomatic. It is estimated that about 20-50% of seniors are asymptomatic.
https://www.cdc.gov/mmwr/volumes/69/wr/mm6913e1.htm
https://www.nejm.org/doi/full/10.1056/NEJMoa2008457

In Singapore, 80% of deaths have been seniors 60 and above, and 1/6 seniors who tested positive developed severe symptoms.
https://www.moh.gov.sg/news-highlights/details/support-measures-for-seniors-during-covid-19

 

[anorlunda]

Enough testing is what is needed to handle any major local outbreak as the economy slowly opens up which she and Fauci expressed confidence that we have that capability now.

The reason you don't see a spec on testing is that the goals of testing are unclear.

Our rolling three day average of new tests is about 1 per 1000 which also is on par with most of the world.

I did, however, run across an article published 12 days ago, which reported that Fauci said he thought the US needed to double the rate of testing. He said he thought we could get there, but it wasn't what was happening at the time.

If only we had enough tracking to know where and how most new cases originate, we could have targeted interventions that are similar in effectiveness to full lockdown, but with much less economic cost.

All those words get us no closer. For anyone to make a factual assertion that "we have enough" or "we don't have enough" there must be a quantitative numerical target, or one target per category.

Fact is not synonymous with truth. An assertion must be able to be independently verifiable by an objective third party to qualify as "fact".

 

[mfb]

Define similar. Similar size? Similar GDP but different population? Is the metric per capita? What tests are being used and how much do they cost? Are they vastly different in complexity? 1% of 330 million is a lot harder than 5% of 3 million. Even the number of tests can be defined differently in different countries.

Per capita, obviously, everything else doesn't make sense.
If your claim would be true then the larger country would simply let 100 subdivisions of 3 million people each handle everything, and magically everything would get easier. Why stop there, let every village organize their own tests, clearly testing 5% of 1000 must be even easier? That's obviously wrong.

As I understand, the in the U.S., the C.D.C. developed our test. The test was complex and cumbersome, and they only allowed certain state labs to use it despite requests from hundreds of private labs to help until the feds encouraged cooperation . But now, the cumulative tests in the U.S. per 1000 is 24.5 on par with many European nations and ahead of some. Our rolling three day average of new tests is about 1 per 1000 which also is on par with most of the world.

Note that I didn't talk about any country in particular. But as you mentioned the US: They screwed up test approval initially because they didn't like the available test but also weren't able to produce their own working test. That is now fixed and testing is at a reasonable level in most states.

All those words get us no closer. For anyone to make a factual assertion that "we have enough" or "we don't have enough" there must be a quantitative numerical target, or one target per category.

Why?
If I could produce one magic vaccine against cancer per day and propose to increase that capability to 10 per day, would you ask about a target number of what is enough? Or would you consider that certainly every reasonable near-future increase will have a clear benefit?
There is no threshold of X tests where you can say "okay, now additional tests are useless" - at least not at numbers that the US could reasonably achieve soon. The marginal use of every additional test decreases, but as long as >5% of these tests are positive that is a small effect.

 

[Vanadium 50]

We're still at 6,000 or so a day. Do we know why we have this number?

Actual infections (as measured by deaths) is dropping. Testing is increasing:

The product of testing rate and positive tests is close to constant. I don't think there's a reason for it beyond "it has to be something."

 

[atyy]

https://www.statesman.com/news/2020...tay-home-orders-some-coronavirus-restrictions
"On top of the face mask mandate, restaurant owners opening up dine-in service are encouraged to keep an activity log of all customers and employees who enter their businesses. The orders ask restaurants to get contact information for all customers and to track where they sat while dining.

Restaurants that refuse to keep logs might have their names publicized by Austin Public Health if the health authority determines the business was exposed to the coronavirus, the order states.

Skeeter Miller, owner of the County Line and president of the Greater Austin Restaurant Association, does not think restaurants will be able to keep track of customers. Many customers will refuse to provide personal information, Miller told the American-Statesman.

“This just isn’t going to work,” he said. “People are going out to eat to get out (of their homes). They’ve been through enough.”"

 

[mfb]

Many customers will refuse to provide personal information, Miller told the American-Statesman.

It sounds absurd, but asking people to pay with credit card will probably face less resistance than asking them to give their names.

 

[morrobay]

Pattaya, Thailand. About $3000

 

[anorlunda]

regarding why do we need numerical targets for testing:

Why?

Because there are enormously important decisions riding on the answer.

Officials in many places are saying "We can't reopen business yet because we don't have enough testing." They are criticized for ruining people's livelihood.

Other officials are saying "We have enough testing. We're reopening now." They are criticized for causing more virus deaths.

The consequences of those decisions are important, yet none of the officials define how much is enough. That gives them no basis for their decisions.

 

[anorlunda]

The orders ask restaurants to get contact information for all customers and to track where they sat while dining.

Many people would either refuse, or give false information. Imagine the trackers chasing false identity data.

 

[atyy]

https://edition.cnn.com/world/live-...09-20-intl/h_33ba54aa936bc907faf121116a74e6d6
All Seoul bars ordered to shut after spike in Coronavirus cases linked to nightclubs

"Tracking partygoers: South Korea has not introduced a nationwide lockdown, but has brought in additional measures to control the Coronavirus outbreak. At nightclubs, for instance, people must provide their full name and phone number before entry.

According to Park, 1,946 names were listed on the registry books of the three clubs the 29-year-old visited. Only 647 of those people have been identified."

 

[DennisN]

24% of tested healthcare employees in the region Västra Götaland (Sweden) were positive for Covid-19. It is the region where Gothenburg, the second largest city of Sweden, is located.

[...]

24 percent positive

The increased testing of healthcare employees in the municipalities shows employees now make up a larger proportion of the confirmed cases than before. Employees were sampled throughout the pandemic. The self-tests that now have been developed have the objective to get employees back to work and they have had a great effect in recent weeks.

- Now the tests have been made in 40 out of 49 municipalities.

[...]

So far, about 600 employees with mild symptoms have done their own test. Of the 550 test responses we have received, 24 percent are positive, says Health and Medical Director Ann Söderström.

[...]

The objective is to increase the number of tests further and to also get validated tests that show if you have had a Covid-19 infection.

(Google translation to English with some corrections by me)

Source: Fjärdedel av testad vårdpersonal i kommunerna hade covid-19 (May 8, 2020, Swedish only)

 

[mfb]

Officials in many places are saying "We can't reopen business yet because we don't have enough testing." They are criticized for ruining people's livelihood.

Other officials are saying "We have enough testing. We're reopening now." They are criticized for causing more virus deaths.

The consequences of those decisions are important, yet none of the officials define how much is enough. That gives them no basis for their decisions.

You can't make that decision based on the number of tests alone. It's not even the most important factor. The reproduction rate depends on many things.
If we would perfectly know the impact of every possible action on the spread of the virus politicians could pick their favorite mix that keeps the virus under control with the least possible impact on daily life otherwise. Testing will be part of the mix, if cases can be found earlier then more restrictions can be loosened. How much in total will vary a lot from place to place. Even the impact of tests will vary from place to place.
Your question doesn't have an answer even in a world with ideal knowledge. But we don't have the ideal knowledge either, and yet politicians need to make decisions with what they know. So we'll see a lot of experimentation. Open schools but keep national parks closed, open beaches but keep schools closed, ... over time people will figure out what works best for their place, hopefully.

24% of healthcare employees in the region Västra Götaland (Sweden) have been tested positive for Covid-19.

That's out of a set of 600 being tested because they experience typical symptoms if I understand the quoted part correctly. It is not 24% of all healthcare employees.

 

[DennisN]

That's out of a set of 600 being tested because they experience typical symptoms if I understand the quoted part correctly. It is not 24% of all healthcare employees.

You are correct.
Edit: Ah, I now see my intro text implied "all" and not "tested", so I have edited it. Thanks!

 

[Bystander]

Many people would either refuse, or give false information. Imagine the trackers chasing false identity data.

Your question doesn't have an answer even in a world with ideal knowledge. But we don't have the ideal knowledge either, and yet politicians need to make decisions with what they know.

Imagine trackers/politicians playing six/seven degrees of Kevin Bacon; the horse left the barn long ago. It is an exercise in futility.

 

[sophiecentaur]

and yet politicians need to make decisions with what they know.

I don't think it works that way. They decide what to do and then look for the 'Science' that justifies those decisions. Sources of advice and information are not treated impartially.
I appreciate that it's hard but only the really good ones can fool all the people all of the time.

 

[kyphysics]

QUESTIONS RE: CASE POSITIVE & IMMUNITY TESTING

1.) I know where to get free testing for COVID-19 case positive testing in my area, but don't know about immunity testing. Does anyone know if there are local immunity test sites anywhere in the U.S. Or, do they not exist yet?

2.) Suppose you got a negative case test for COVID-19 and/or a positive immunity test (meaning you have anti-bodies). Would you trust it? Would you demand/try for a 2nd...3rd test just to be safe?

I've been wanting an immunity test for so long. Then, I realized it could be inaccurate and wonder what use it would be for me. Here is a person who took four tests and still doesn't know what to make of things:

After Four Antibody Tests, I’m Still Not Sure I’ve Had Covid-19
https://www.bloombergquint.com/busi...ibody-tests-may-produce-contradictory-results

 

[kyphysics]

3.) This is a weird question, but would it be a risk to go to a drive-thru free COVID-19 testing site and end up CATCHING the virus there. Suppose you're negative. You wait in a long line of cars where tons of people are trying to get tested. You may figure some of these folks have legit worries, as they may have symptoms. Some will definitely test positive. They are talking, breathing, and sneezing, etc. in line. The wind is blowing. The workers performing the tests could get the virus on themselves and then when you drive up for your turn maybe the wind blows it on you or you get it from whatever object the testers touch you with.

Is that a low enough probability event that it's worth going out to get a free test. I've seen the lines. They are LONG. I don't go out except for essentials (groceries and gas). Wondering if it's actually risky to get tested.

 

[Janus]

QUESTIONS RE: CASE POSITIVE & IMMUNITY TESTING

1.) I know where to get free testing for COVID-19 case positive testing in my area, but don't know about immunity testing. Does anyone know if there are local immunity test sites anywhere in the U.S. Or, do they not exist yet?

2.) Suppose you got a negative case test for COVID-19 and/or a positive immunity test (meaning you have anti-bodies). Would you trust it? Would you demand/try for a 2nd...3rd test just to be safe?

I have a niece who is a nurse. A while back she went through a bout with something that might have been COVID-19. She had an antibody test a week or so ago, and it came up positive. However, a more recent retest came back negative.

 

[bob012345]

I have a niece who is a nurse. A while back she went through a bout with something that might have been COVID-19. She had an antibody test a week or so ago, and it came up positive. However, a more recent retest came back negative.

I have a friend who swears he had C19 but then an antibody test came back negative. It's not clear if these test are very accurate. What are the odds of a false positive vs. a false negative?

 

[BillTre]

I have a friend who swears he had C19 but then an antibody test came back negative. It's not clear if these test are very accurate. What are the odds of a false positive vs. a false negative?

From what I have read, there are several different test (with more coming).
Some of them re considered good some are not.
I don't know which are which.
Apparently (in the US anyway), which tests are available is not regulated.
And I doubt that this government could even generate a credible recommendation (although , some individuals in the government could).

A while back she went through a bout with something that might have been COVID-19. She had an antibody test a week or so ago, and it came up positive. However, a more recent retest came back negative.

Interesting. About a week apart?
Was it the same test in both cases or possibly different tests?

 

[Keith_McClary]

Many people would either refuse, or give false information.

In USA they might be worried about being sued if they infect others.

 

[Janus]

From what I have read, there are several different test (with more coming).
Some of them re considered good some are not.
I don't know which are which.
Apparently (in the US anyway), which tests are available is not regulated.
And I doubt that this government could even generate a credible recommendation (although , some individuals in the government could).Interesting. About a week apart?
Was it the same test in both cases or possibly different tests?

I assume that it was the same test, as it was part of a research project. She also just had a third test (no results yet), but since I wrote my last post, we heard from her mother that funding for the project was just cut.

 

[bob012345]

From what I have read, there are several different test (with more coming).
Some of them re considered good some are not.
I don't know which are which.
Apparently (in the US anyway), which tests are available is not regulated.
And I doubt that this government could even generate a credible recommendation (although , some individuals in the government could).Interesting. About a week apart?
Was it the same test in both cases or possibly different tests?

I remember hearing Dr. Fauci insisting that there was virtually no threat from this virus. Don't stop travel. Don't stay home. Then stop travel. Then stay home. But it's harmful to wear masks. Then it's good to wear masks...

 

[atyy]

A few confirmed cases in Singapore are found to be false positives. This test refers to the PCR test, not an antibody test. There are several checks one can do for false positives and false negatives. I am not sure which ones are referred to in this new report, but I suspect these are the standard ones that are done with every test (or that can be done by doing another test on the same sample) - they probably don't exclude other types of false positives and false negatives.

COVID-19: 33 cases found to be 'false positives', including healthcare worker at Singapore Expo community care facility
https://www.channelnewsasia.com/new...alse-positive-singapore-moh-33-cases-12719588

 

[OmCheeto]

...politicians need to make decisions with what they know

My governor has put her faith in the Harvard's Global Health Institute's recommendations. I just wish I could understand how they get their numbers. Specifically, the "target tests per 100k". Has anyone else tried to figure this out?

 

[vela]

I remember hearing Dr. Fauci insisting that there was virtually no threat from this virus. Don't stop travel. Don't stay home. Then stop travel. Then stay home. But it's harmful to wear masks. Then it's good to wear masks...

What's your point? Recommendations change as information is learned and the situation evolves.

 

[OmCheeto]

What's your point? Recommendations change as information is learned and the situation evolves.

Snopes says that was from a Feb 29 interview, when 1 person had died so far in the US, in case anyone is interested in what Dr. Fauci actually said, without having to rely on their memories.

 

[Evo]

Hi. Wife is buying these masks from Lazada. Do you think PM2.5 masks protect against Covid-19?

3 layers with respirators View attachment 262366View attachment 262367View attachment 262368

5 layers with respirators

View attachment 262369View attachment 262370

I would greatly appreciate any response. Thank you.

You shouldn't use masks with valves.

Some of these respirators have valves that allow exhaled air to get out, making it easier for the user to breathe. However, the downside of this is that other people are susceptible to the particles and pathogens that are exhaled through these valves.

https://www.healthline.com/health/best-face-mask-2#materials

Sorry, I had read this in a better medical site previously, but don't have the link now.

 

[PAllen]

Since this is a physics site, I’ll make a basic physics point that applies to all masks that I have seen or tried (I don’t know if it applies to N95, as I have never examined one. It definitely applies to surgical masks).

This is triggered by @Evo ’s comment, but generalizes it. Almost all sources keep saying masks are better protection for others than the wearer. I wish this were so, but I argue that this is absurd for a simple physical reason I have demonstrated on about 8 different masks. That is, that inhalation creates negative pressure that helps seal the mask around your face, giving close to the best filtration possible by whatever the mask material. In contrast, exhalation creates positive pressure that opens the mask face boundary, leading significantly more air to bypass filtration than on inhale. I have verified this for even tightly fitted professionally made masks. Unless the mask has an actual sealing agent, I don’t believe there is any way around this.

Thus, contrary to the common wisdom, you get most of filtration possible on inhale, and much less on exhale, so it is less effective at protecting others than you. Of course, everyone wearing masks mitigates this.

 

[anorlunda]

Almost all sources keep saying masks are better protection for others than the wearer.

It is not exhalation that is the problem, it is the cloud of droplets spread by a cough or a sneeze. That's how masks protect other people.

 

[PAllen]

It is not exhalation that is the problem, it is the cloud of droplets spread by a cough or a sneeze. That's how masks protect other people.View attachment 262524

But some of the sneeze droplets would get out the mask face boundary unfiltered, especially because positive pressure during a sneeze is much higher than an ordinary exhale. Conversely, sneeze droplets by someone else would be captured more effectively by you inhaling through a mask. My point still stands that basic physics of pressure without an airtight seal suggests the opposite of the common claims of effectiveness of masks.

In effect, they all have valves on exhale.

Just to be clear, I am in no way claiming that you wearing a mask doesn’t protect others. What I am disputing is the claim they protect others better than they protect you.

 

[atyy]

Since this is a physics site, I’ll make a basic physics point that applies to all masks that I have seen or tried (I don’t know if it applies to N95, as I have never examined one. It definitely applies to surgical masks).

This is triggered by @Evo ’s comment, but generalizes it. Almost all sources keep saying masks are better protection for others than the wearer. I wish this were so, but I argue that this is absurd for a simple physical reason I have demonstrated on about 8 different masks. That is, that inhalation creates negative pressure that helps seal the mask around your face, giving close to the best filtration possible by whatever the mask material. In contrast, exhalation creates positive pressure that opens the mask face boundary, leading significantly more air to bypass filtration than on inhale. I have verified this for even tightly fitted professionally made masks. Unless the mask has an actual sealing agent, I don’t believe there is any way around this.

Thus, contrary to the common wisdom, you get most of filtration possible on inhale, and much less on exhale, so it is less effective at protecting others than you. Of course, everyone wearing masks mitigates this.

In another thread, some evidence was posted against the effectiveness of masks as protecting others. However it did not rule out that masks protect others from the wearer in some other reasonable ways, merely in the way that was tested.

https://annals.org/aim/fullarticle/2764367/effectiveness-surgical-cotton-masks-blocking-sars-cov-2-controlled-comparison
Effectiveness of Surgical and Cotton Masks in Blocking SARS–CoV-2: A Controlled Comparison in 4 Patients
Seongman Bae, MD *; Min-Chul Kim, MD *; Ji Yeun Kim, PhD *; Hye-Hee Cha, BS; Joon Seo Lim, PhD; Jiwon Jung, MD; Min-Jae Kim, MD; Dong Kyu Oh, MD; Mi-Kyung Lee, MD; Seong-Ho Choi, MD; Minki Sung, PhD; Sang-Bum Hong, MD; Jin-Won Chung, MD; Sung-Han Kim, MD

 

[PAllen]

I should say the main test method I used is a chilled slide held in various positions near a mask on exhale. An inch front of the mask produced no fogging, while positions near the mask boundary produce a lot.

 

[atyy]

It is not exhalation that is the problem, it is the cloud of droplets spread by a cough or a sneeze. That's how masks protect other people.

Actually, depending on how the policy is sold, it may be exhalation that is the problem being considered.

If one is coughing or sneezing, one should simply self-isolate, then the question of mask to protect others does not even come into play.

In some cases, the mask is said to protect others because of the possibility of pre-symptomatic or asymptomatic transmission (eg. between barber and customer getting a haircut, both of whom feel well, and who need to be in non-transient close contact), which would mean transmission by normal conversation or exhalation.

Edit: I should say some asymptomatic people do cough (definition of 'asymptomatic' is variable) - they have chronic cough, and don't notice anything markedly different from normal. https://www.nejm.org/doi/full/10.1056/NEJMoa2008457