A new paper in the British Medical Journal has an excellent set of visuals on behaviors and COVID risk:
I love this. This is actionable information on how to think about transmission risk. There is a another critical dimension to consider; background community infection levels. Regions like Vermont with 1 new case per 100,000 residents per day will be facing systemically different risk than areas like Mississippi where there are 20 or more new cases per 100,000 residents per day. However, that is extra complexity on simple guidance.
- Stay outside whenever possible
- Mask up
- Ventilate
- Short contacts
- Quiet
These are actionable steps on figuring out what types of activity are more or less risky.
I currently go to my gym and deadlift in the parking lot where there is plenty of space, outside, short contacts in a well ventilated environment.
I get tweaked out looking at the Starbucks down the street from the gym as there are prolonged, close contacts. Some of those contacts are outside on the patio and more are inside.
This is simple, straightforward, evidence based guidance that can allow for more normality at marginal increases of risk. That type of guidance can be very valuable.
Ken
I’m glad to see an actual study, I was relying on the xkcd version.
This makes it clear that mask mandates and banning certain types of indoor activities will help, but will that lead to policy changes in the US? I fear not.
raven
The aquatics guy at the Y contacted me yesterday and outlined busy and slow times at the pool and encouraged me to check it out. I bought a stationary recumbent bike and am just getting into it (60 to 90 minutes A DAY, say what??) and I’d like to swim but I’m just not sure yet.
Wapiti
That’s nice. I’m taking my niece out driver’s training today (and have in the past). Masked, windows down, mostly. Speaking. Looks pretty safe.
Old School
On a quick scan, I couldn’t see what the authors considered to be a “short time” and a “prolonged time”. Would 15 minutes at a Starbucks be considered prolonged? One hour?
trollhattan
Cycling has really helped my mental and physical well-being. The heatwave, followed by the wildfire smoke has halted that for nearly two weeks but this too shall blow away at some point (going hiking in the meantime). Am having difficulty envisioning returning to a traditional office and if so, when in 2021 would be the earliest it could be done. Not this year. Nope.
Who’s up for some public shouting on January 20?
MattF
The problem is that each and every time you leave your home to do something, you take a risk. A small risk, but non-zero. And those risks add up independently, as risks do. So, you have to take your to-do list and remove things that are inessential or inherently risky. And after that… who knows?
trollhattan
@Old School:
A fair question. Sitdown meal, church service, clearly long. Grabbing a takeout order, short but where’s their cutoff?
My Costco has…40-foot? ceilings, mandatory masking and distancing and put bigass ceiling fans over the checkout area, and I feel pretty safe there. Other stores with tight aisles and checkout areas, ’60s vintage HVAC systems I want to grab and go because I suspect the conditions will overwhelm our defenses. That’s the unknowable part with an invisible foe.
Steeplejack (phone)
@Old School:
I would not spend 15 minutes in a Starbucks. After you’ve gotten your coffee, what’s the point? Regardless of social distancing, you’re sitting there letting the HVAC system blow everything it has collected back onto you.
Old School
@trollhattan: I tend to agree with you, but we have our own biases. I haven’t eaten out at a restaurant (dine-in) since the shut downs began. Others I know have and think that an hour at a restaurant isn’t a long time. They have a different definition of “prolonged”. I was curious to see the research (and obviously prove that my definition is correct).
Yutsano
@trollhattan: I did a quick but targeted scan of the research paper. And the answer is…it depends. And even then it’s ambiguous at best. I could see the chart being handy for personal risk but there’s no real definition of what is a true safe distance and what is not. It depends on the context of the situation. And even then it has no hard answers. Basically: they don’t know what they don’t know and what they do know is so fluid that they say a sort of “look at the chart” is about the best they can do right now.
CaseyL
@MattF: I’m not sure individual small risks are cumulative, though.
I go grocery shopping (masked) once every 7-10 days; I go into my office (masked) once a week, and have minimal interactions with other people, also masked.
If I add up all that exposure time over a month, it looks moderately dangerous – but I don’t think that’s how the viral load/duration calculation works. Maybe over the course of a day, but not longer.
I think.
MattF
@CaseyL: Well, if you went out twice as often, there would be twice the risk. Another way of thinking about it is that there’s a more-or-less fixed probability of encountering something bad each time you go out, so more going out is more bad.
ETA: Excluding things that are obviously dangerous, like choir practice.
Cermet
For those in the path of Laura and sheltering in proper centers, keep the masks on; even reduced exposure could mean far better chance to get a mild form. Of course, all BJ’ers in the path need to evacuate now before you can’t. Try to stay safe.
Barney
Thinking of a school classroom, I’d say it’s somewhere between ‘low occupancy’ and ‘high occupancy’, ‘indoors and well ventilated’ and ‘poorly ventilated’ (at first, when outside temperatures are OK, and plenty of windows can be opened; in some places, ‘poorly ventilated’ once it gets colder). And there’s some speaking, but a lot of people are silent. It’s a prolonged period, and in the UK, proposed as unmasked in all schools, despite the WHO recommendation of masks for those 12 and older.
Which is in the red zone, but not too far from the yellow. Wearing masks would push it into the yellow. Effectively, by saying they won’t recommend masks in classrooms, they’re just saying “once one person in a class gets it, assume they spread it to most”.
Matt McIrvin
@MattF: A thing I’ve really been struggling with is the tradeoff between social notions of “fairness” and risk reduction. There’s always the question “If it’s OK to do X with him, why isn’t it OK to do Y with me?” Fairness seems to imply that being lax about one thing means you also need to be lax about another thing, but risk reduction pushes the other way: to keep your (and everyone’s) overall risk low, doing one risky thing means you should be LESS willing to do other risky things. You have to make your choices and they can’t necessarily be fair.
And this applies more generally to things like grocery shopping vs. church, protest demonstrations vs. in-person voting, etc. “If X then why not Y? That’s unfair” pushes us gradually in the direction of opening up everything and letting it rip.
raven
@Matt McIrvin: A PSA for protestors. If you hear gunshots at a protest and see a guy run past you with an AR-15 do NOT punch him.
Matt McIrvin
@raven: Depends! You might die but save ten other people’s lives. The risk calculation could be pretty complicated…
MattF
@Matt McIrvin: I think it’s OK to make somewhat arbitrary choices. E.g., I’ve decided to postpone a colonoscopy that is due around now, but I’m not going to postpone a surgical eye procedure that will improve acuity in one eye. Both about equally risky, I’d guess. Lowering your total risk is a nearly unqualified good thing, IMO.
raven
@Matt McIrvin: It’s hard to tell but on the facebook live vid it looks like one of the dead and the guy shot in the arm here hit after the dude punched the proud boy.
Ohio Mom
This chart fits with what I’ve been doing: on the rare occasions other people are going to be on the house, say when we called the plumber, I open all the windows.
What we do starting in November, I do not know. Wear our coats and gloves inside and run up a huge heating bill? When you need a plumber, you can’t put it off.
Feathers
There is a (very) local restaurant which was not doing well at all in the before times. Since reopening, it has had more customers than it did before. It should be fairly safe, low infection rate here, no off street parking, so most of the people have walked there, entire street frontage has full windows which are open, but… it freaks me out. I realized what some of it is that people take their masks off as soon as they sit down and are chatting away with each other. It’s as if the restaurant is a magic safe zone. Everyone is masked up on the street. They also hang out long after they are done eating.
I’m also pissed off generally that the owners of one of the nearby buildings raised their rents and the mom-and-pop fresh fruits and vegetables store closed in December. Really could have used that now.
LeftCoastYankee
So “shut up and wear your mask” is technically good advice?
On a serious note, I’m thinking indoor exercise would fall in the singing/shouting “lane” due to the potential for deep breathing.
I haven’t seen anything about transmission through sweat… Is that even a possibility?
Unique UID
Thanks for highlighting that graphic!
We have been quite cautious, the first several months I didn’t go into a single building.
I am curious about risks of takeout food? Any good data on that? Personally, I think it should be quite low risk, but my wife is very reluctant.
We have been using curbside pickup of groceries, but I am tempted to mask up and do quick shopping trips just because it would be so much easier.
I’m in mid-Michigan, was acquainted with a certain library worker at MSU a long time back.
(perhaps my first successful comment here? I tried a few months back, but didn’t make it thru moderation, I guess)
Brachiator
People should also consider social bubbles, that is, limiting the number of other people you might choose to socialize with. And this would include family members you don’t live with.
ETA. You might need a separate chart for college students, taking parties, indoors and outdoors into account. I suppose the chart might be all red.
Uncle Cosmo
I’m almost certain you’re correct and MattF is mistaken.
Pathogens (as well as toxins and chemical agents) tend to show a distribution that’s characterized by the ED50 – the effective dose at which 50% of those exposed contract the illness. In the case of a virus, the question is how many viral particles need to be introduced into the body for it to take hold & multiply.
My take is that most of those exposed to a small number of viral particles either expel them when they breathe out, or manage to kill them off before they can get a toehold. Both processes likely take very little time – hours at most – after which you are virus-free.
In which case, repeated exposures to virus at intervals of several days are more like independent events: Each one is a separate “crapshoot” re infection. Remember, the only reason we’re told to “quarantine” for a period of time is to see if we have enough virus in our system for it to multiply & show it (symptoms and/or antibodies). That is thought to take 10-14 days at most – though IIUC usually such effects show up after 4-5 days & if they don’t one is very likely not to be affected. So it looks like venturing forth once a week or so, if nothing untoward has surfaced in the interim, is a fairly conservative & prudent policy.
At least that’s how I’m dealing with it – & by virtue of age & comorbidities I have a bullseye stenciled on me. So far so good.
LeftCoastYankee
@Uncle Cosmo:
Thanks for this reminder:
What’s hard to keep straight (at least for me) is what measures are more “public health” and which are more “personal health” suggestions. Obviously there’s overlap, but when I can keep the two thoughts at the same time, it does become clearer.
Brachiator
I’ve been reading the reactions to upcoming films at various movie sites. Especially the reactions to DC super hero movies such as the upcoming Batman reboot. But no one talks about whether or not people will go back to movie theaters. And the people who want to have home streaming for everything don’t consider whether this would affect the amount of money spent to produce big blockbusters.
Brachiator
@Steeplejack (phone):
I’ve noticed people waiting a longish time for their drink order to be made at a small Starbucks. Folks did try to maintain some social distance.
WaterGirl
@MattF: What I wonder is this. What if I make a 10-minute trip to the store every week, vs. a 40 minute trip once a month.
Seems to me that I have a better chance at hitting a viral load on the one long trip, as opposed to the 4 in-and-out trips.
My rule of thumb is that one of the real experts on this said something like:
if you’re in a car, masked, with someone who has COVID, you’d likely be okay for a 10-minute trip, but with a 20-minute trip, you are pretty much going to get COVID.
Do not have a link, but that told me that it’s a lot about exposure time. So I think of anymore more than 10 minutes as long.
I would still like to know where they drew the line for that chart, however!
Bill Arnold
@MattF:
I watch the level of active infections (per million) in my area, multiply by 10 to account for worst case (high rate of asymptomatic infections, and uneven distribution of infecteds) and use that to estimate the max probability that another individual is infected, doubling if they’re a known Trump voter or obviously ignoring precautions.
My county is at approximately 600 active (tested) cases per million (not quite as low as e.g. Vermont), so assume 6000, which is 0.6 percent, or 1/167 (max) that a person being interacted with F2F is infected.
Matt McIrvin
@LeftCoastYankee: It really requires thinking simultaneously in two alternate timelines–the one where you’ve got the virus and are trying not to spread it, and the one where you don’t have the virus and are trying not to catch it.
Matt McIrvin
@Brachiator: You also have to be careful that those people’s definitions of the bubble are the same as yours. E.g. you figure you’re bubbled with person X but lo and behold, they think they’re bubbled with Y and Z and so on and suddenly you’ve got this chain for viral percolation stretching across multiple states. That’s causing me some angst now.
(Though infrequent contact with effective quarantine time in between could help mitigate that.)
Snarki, child of Loki
It’s really easy to evaluate risky/non-risky behavior. Just check the https://xkcd.com/2333/ chart.
Matt McIrvin
@Brachiator: Some movie theater chains, which are obviously hurting, have brought their prices for private screenings way down–you can rent out a theater just for you and a few people in your social bubble, lower prices for older movies than for first-run ones.
Obviously there are still risks involved; they claim they’re wiping down everything between screenings etc. but I doubt that’s even the most relevant risk vs. aerosolized virus through the A/C system, etc. But it’s not the same as seeing a movie with strangers.
Albert Torres
@Snarki, дитя Локи: Thanks for sharing!
Matt McIrvin
@Feathers: I don’t do sit-down restaurant dining, even outdoors. Freaks me out just being around all those strangers without masks, chatting away while they eat their food. I’ll do takeout and eat it in the park. I do other things that are probably riskier but, as I said, “if X then why not Y?” probably isn’t a productive line of thought.
Mom Says I*m Handsome
A month ago I asked the commentariat whether I should allow my daughter to participate in a volleyball training camp (outdoors, no masks, low occupancy, prolonged exposure, high exertion). According to this excellent graphic, that has a Yellow risk, which validates my final determination to have her not attend.
So I’m very pleased to say that when she was invited to a birthday party (outdoors, masked, low occupancy, prolonged exposure, talking) I was cautious but said Yes. And the chart supports me! All hail the chart!
One other thing about this whole Rona* situation is that has, once again and in bold letters and all caps, highlighted how bad humans are in assessing risk. We take confirmation bias, racism & xenophobia & bigotry, mix it up with innumeracy, and end up either paralyzed at home** or throwing all caution to the wind and carrying on as if we’re powerless to take ANY steps, like wearing a goddamn mask.
* George Wallace suggests calling it Trump Mumps.
** I’m in this camp because the risk of failure in my household will literally be fatal.
Matt McIrvin
@Mom Says I*m Handsome: My daughter’s martial-arts classes reopened in similar fashion–outdoors with masks not required, with the option of going indoors with masks required if the weather got bad.
I was, honestly, really, really uneasy but we let her decide. She went to a couple of sessions and said, nope, she just wasn’t confident their safeguards were adequate. So she’s not going at the moment. We haven’t decided on long-term plans.
catclub
although, I look at things the other way, too. It turns out that your life excpectancy for dying in a car accident, if your are in a car 24/7/365
is over the average life expectancy in the US. Most people die in their beds.
The point of going out is presumably there is a need and a benefit.
People drive more when the economy is good and they have jobs to go to.
Bill Arnold
@MattF:
I watch the level of active infections (per million) in my area, multiply by 10 to account for worst case (high rate of asymptomatic infections, and uneven distribution of infecteds) and use that to estimate the max probability that another individual is infected, doubling if they’re a known Trump voter or obviously ignoring precautions.
My county is at approximately 600 active (tested) cases per million (not quite as low as e.g. Vermont), so assume 6000, which is 0.6 percent, or 1/167 (max) that a person being interacted with F2F is infected.
Roger Moore
@Steeplejack (phone):
The point is to hang out and take advantage of their WiFi. In the pre-COVID days, lots of people would buy coffee from Starbucks basically as a way of paying an hour or two’s rent for an air conditioned seat with internet access.
raven
@Matt McIrvin:
17 year old Kyle Rittenhouse appears to be the killer and he shot at least 2 people after he was knocked on his ass.
WaterGirl
@Unique UID: I just approved your first comment, and you should be good to go from here.
Yutsano
@raven: There’s no statute of limitations on murder. So Mr. Rittenhouse better keep his fool nose clean. Also: the Kenosha police department needs to be disbanded.
Roger Moore
I’m wondering what this says about taking the train to work. I have been commuting by car since the COVID crisis started, but my employer is doing some major construction work that is removing much of our parking. I am no longer going to be allowed to part at work, so my options are:
The length of the rides will be similar, and I think they would count as a short exposure. I guess this table makes it look like those to situations are similar in terms of risk.
Calouste
@Steeplejack (phone):
I believe the point is to show off that you can afford the latest MacBook, but can’t afford proper internet or a decent chair at home. At least that is what it has looked like at my occasional visits.
raven
@Yutsano: Nose clean, he murdered two people?
Gin & Tonic
@raven: Reuters reporting that he’s been arrested and charged with homicide
ETA: “First-degree intentional homicide.”
raven
@Gin & Tonic: Yea, I’ve been following it but I probably should stop.
StringOnAStick
We did one camping trip this summer with very careful friends, but others in the camping area were hit or miss. We decided before we went that we wouldn’t bring our instruments because of the transmission risks from singing, or of other people bring freaked out by the risks posed by singing.
It was our first and last camping trip until it gets cold enough to significantly reduce the number of other campers.
Feathers
@WaterGirl: From my time in the research trenches, my guess is that they were using multiple datasets which had differing definitions of short duration. But, yeah, a lot of the papers I’ve seen count 10 minutes as short, so that is what I’m calling short.
@Matt McIrvin: Boston area peeps, the Brattle is offering theater rentals for $350 for up to 15 people, $250 for Brattle members. Theater cleaned between each screening.
WaterGirl
@Feathers: That’s kind of where I land, too.
Feathers
@WaterGirl: I’ve been craving a restaurant burger. Have decided I’ll go by myself, to a great place that has windows that can open, be there when they open, and stay masked until my burger arrives. I’m guessing I can finish it in under 10 minutes, so I should be good. Right?
WaterGirl
@Feathers: We all have to make our own decisions, but I would not do that.
Take it to go and eat it in your car, so it will still be hot.
Uncle Cosmo
@Feathers: What you need are disposable nose filters, one per nostril, and CPAP discipline (breathe in thru nose, out thru mouth): Plug them in as the burger arrives, one deep breath per one chomp&chew; discard when finished, wipe nose, mouth & fingers with high-%-alcohol-soaked towelette, re-mask, wash hands thoroughly.
(Main problem: Not sure nostril-size filters of needed impermeability are available anywhere. Oh well.)
jlowe
Good risk communication! After skimming the paper, the one limitation I see is that the ventilation categories will be highly situational (for indoors, building and room size, roof height, effectiveness of air mixing, air-exchange rate, occupancy). I am aware of work being done with indoor exposure models which may be able to place more detailed specifications on those categories
Albatrossity
Excellent information. I can recommend birdwatching (or butterfly-, or dragonfly-watching) as an activity that would generally be silent, outdoors, and with little or no contact with potential infected persons!