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Coronavirus updates: San Francisco imposes stronger mask requirements - Printable Version

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Coronavirus updates: San Francisco imposes stronger mask requirements - 2006alum - 05-29-2020

Quote:The City of San Francisco is now requiring that individuals wear masks whenever they leave their homes and interact with people outside their households.
The city previously only required masks in mostly indoor situations, but it now mandates that individuals wear masks when exercising less than 30 feet from others or when passing people on the sidewalk.
During a Thursday press conference, Mayor London Breed stated that businesses have the right to turn away any individuals who are not wearing masks, but asked that individuals not confront non-mask-wearers.
"If you are not the police, please don't act like the police," she said. "The last thing we want to see are people who are confronting other people and creating what could escalate to a violent situation. Just let us do our job."


Am I the only one that thinks this is too extreme? First, is there any evidence that someone running or cycling by a mask-wearing pedestrian at a 10-15 foot distance poses even the tiniest risk of spreading the virus? And 30 feet is such a long distance that it effectively rules out any kind of exercise without a mask unless you're in an empty football field.

I also think it's misguided because SF police have cited only a few dozen people for SiP violations in the past two months - and if citizens are discouraged from social shaming (which I think is the right call), then there's unlikely to be effective enforcement of this rule. I also always wonder with these kinds of edicts, how much notice must be required? I happened to pull up SFGate this morning. But what if I hadn't? What about all the people avoiding the news, etc.?

Curious what others think about this. I think I've tended to be on the "let's risk overreacting" side of these debates so far, but this feels a bit too far even for me. But maybe that's just because it will massively inconvenience me, since there's no way I can run at the pace I prefer and wear a mask without feeling like I'm always about to pass out (I've tried).

RE: Coronavirus updates: San Francisco imposes stronger mask requirements - dabigv13 - 05-29-2020

Seems silly and counterproductive. I worry it will increase "mask-fatigue", when wearing masks is actually really good health policy in the proper settings.

RE: Coronavirus updates: San Francisco imposes stronger mask requirements - OutsiderFan - 05-29-2020

This is tough. I was wearing a mask every time outside the house up until two weeks ago. I still wear one if I go inside with others, but given there has been no reporting of people getting infected from simply passing by others at least 6ft away, I stopped.  And remember, I'm in a county with the most deaths per capita in the country, predominantly in LTCF. Speaking of them...

Yesterday my infection control nurse friend who works at LTCF came by and dropped off some surgical masks for me. He was saying this virus is incredibly easy to transmit, talking about surface spreading in particular, something I have become less concerned about over time. He was off my porch and neither of us were wearing a mask while talking, probably 10 feet away. He also told me wearing a mask too long makes you breathe in so much more C02 (don't know what kind he was referring to exactly), that your blood oxygen level goes down even if not sick, as a result of re-breathing so much exhaled air. He equated it to exercising at high altitude.

Of course, when I go out in West Hartford, CT, I'm not likely to encounter too many people. I only passed by one this morning who walked way around me. In San Francisco, it's much more densely populated. Even in the Sunset and Outer Richmond you can encounter a good number of people. But there is also the fact more things will likely open sooner if everyone wears a mask. Not only will the mask wearing protect more people, but the case numbers will go down as well, leading to more economic activity.

IOW, if the city couches it as a "if everyone wears a mask we'll be able to go out more," compulsory make wearing can work. If it's couched as "wear a mask or get fined," then it's not going to go over as well.

RE: Coronavirus updates: San Francisco imposes stronger mask requirements - M T - 05-29-2020

(05-29-2020, 08:21 AM)OutsiderFan Wrote:  He also told me wearing a mask too long makes you breathe in so much more C02 (don't know what kind he was referring to exactly), that your blood oxygen level goes down even if not sick, as a result of re-breathing so much exhaled air. He equated it to exercising at high altitude.

Hmm... 'Exercising at high altitude" doesn't sound right to me at all.  There are primarily 3 gases to think about in air: O2(21%), CO2 (< 0.1%), and nitrogen (78%).  Unless you're diving, we can ignore nitrogen.  Exhaled air consists of 78 percent nitrogen, 16 percent oxygen, 4 percent carbon dioxide

Masks have different amounts of residual air that stays inside the mask.  Some masks (most N95s) have a lot of volume inside, while others (disposable surgical masks) have little.   The larger the volume, the larger the surface area, so (for the material) easier to draw.   But the air in that volume will be exhaled air.  A little less oxygen, and a lot more CO2.

I would think a N95 mask contains maybe 5-10% of the volume of a breath.  At 10%, that becomes about 0.4% CO2 in your lungs.  That's well higher than normal air.  So your CO2 level in the blood leaving your lungs is higher.  The O2 level will be less, but I don't think that will be too significant (20.5% vs 21%), and could be considered some what related to being at slightly higher elevation (in terms of O2 molecules, not % O2).

As I understand it, your body more readily responds to CO2 levels in your blood.  Higher CO2 means faster breathing among other things.  But I imagine there ae chemical changes as well.

Now, if you breath faster, you might actually expose more O2 molecules to your blood.  But that's where my understanding breaks down.  I don't know whether the blood will preferably exchange CO2 for O2 in the faster breathing but 0.4% CO2 scenario.     (And I'm not sure what causes the dizziness that one gets from hyperventilating (remember its treatment may involve intentionally rebreathing your exhalation in a paper bag.)   I do know that at high pressure (ie, scuba diving), too much oxygen is a problem ("oxygen poisoning"), but I don't think that is a problem here.)

But I wouldn't automatically presume you'd have much less oxygen in your blood.  I do believe you will have more CO2, and that will likely be the important factor. (Possibly more important psychologically as well as physically.)  You may also be expending more energy just for the breathing.

I have decreased lung function.  When I go anaerobic due to exercise, I quickly devolve to a state where I feel I can't get enough air.  Psychologically that's very scary.

We do know that other cultures have been wearing masks a lot over the past 20 years.  I expect they've studied this, but I am not certain.

RE: Coronavirus updates: San Francisco imposes stronger mask requirements - OutsiderFan - 05-29-2020

He cited some percentages of 02 and C02 with and without mask, but don't remember what they were. My guess is wearing the N95 mask is the culprit to breathing in more C02 than you do not wearing any mask. I have used cloth and surgical and not ever sensed any less 02 available, and I have not worn an N95.

I have breathed in and out of a balloon before and know what it's like to experience taking in more C02 and less O2. Masks do obviously breathe, but you absolutely will take in more C02 with a mask than without one, for the same reason having a mask will stop droplet spread more than no mask. My only question is will the amount of C02 inhaled wearing a mask be enough to ever have a physical impact. It may also depend on the person and their respiratory fitness.

He did say after being around Covid and wearing a mask all day he just doesn't have the same energy he used to have at night after his work shift.  But I also know those working around the disease have to be stressed and fatigued as a result as well.

RE: Coronavirus updates: San Francisco imposes stronger mask requirements - Snorlax94 - 05-29-2020

I agree that I think the policy, as written, is a miscalculation and I hope they refine it. I jogged up a few floors wearing a tight earloop mask and had difficulty recovering my breath.

But when I drive through downtowns on weekends in SCC, people are just hanging out, and about 40-60% of people are not wearing masks. Because they are strolling through a downtown, arguably, they are "exercising," but doing so with friends, at a slow pace, probably stopping inside restaurants to purchase things.

How do you restrict these people from stepping indoors and potentially talking and coughing, or from just "taking a break" during their walk to talk to friends on crowded streets, for a prolonged period, all without wearing masks?