I heard it came from a study of a sick person on an airplane and looking at the passengers around them that then ended up getting sick.
That makes sense. But is that truly the source of the 6’ rule or does it have to do with distance droplets travel?
Is the 6’ rule how far droplets (to within an error) travel when sneezing or coughing or is that just with normal conversation?
How effective is turning your back to someone who is within 6’ of you?
If Person A is infected and facing north and breathing regularly, if I’m behind them can they really be spreading droplets 6’ behind them? The physics on that don’t really work for me.
Similarly, even if they sneeze how can the propel droplets 6’ behind them?
I understand keeping 6’ is good guidance because it could be the person behind that is sick, but I’m wondering how worried people need to be about catching anything from someone facing away from them.
Remember; measure with a micrometer, mark with chalk, cut with a chainsaw. No person is capable to telling the practical difference between the two and honestly in this situation 5=7 too.
Since the two measurements are not equal, and since ~six inches / ~15 cm is not really a rounding error, which was determined as the initial measurement?
Was 2 m an approximation of 6 ft for those in metric countries, or was 6 ft an approximation of 2 m for Americans?
“It doesn’t really matter” is rather dismissive. I’m happy to accept “It makes no practical difference in terms of people’s social distancing behaviour,” but that’s kind of answering a question nobody asked. I thought this was a thread asking where the specific number of 6 ft / 2 m came from. In which case it does matter.
But yes, make all the jokes you like about how ridiculous it is to use precise measurements in a discussion about precise measurements.
Or 6.67128190396 light-nanoseconds. However, due to the Bouguer gravity anomaly in the continental United States, the adjusted value is closer to 6.34251934059 light-nanoseconds, and for ease of use by non-physicists the CDC just rounded it to “6 feet”.
Six feet / 2 metres was selected, I suspect, because it’s just a distance most people can understand and eyeball. More is probably better, but it’s hard to visually figure out what 10 or 15 feet is, and if you ask people to do difficult things they often won’t do them at all. Six is also practical to apply in situations 10-15 would not be.
Here’s a study that suggests some of the droplets if someone coughs directly into the air can carry well beyond 2m. Approximately 2m is a reasonable compromise between safety and practicality. They also found the droplets can stay in the air in the 2m area for up to three minutes. But that’s someone forcefully coughing without covering up, which I’ve never seen anyone do yet. For someone who may be shedding the virus just through breathing, 2m is probably more than adequate.
On the positive side, I’ve also read that any typically small amounts of such infectious droplets are unlikely to contaminate hair or clothing because the airstream dynamics around slow-moving humans tend to push airborne particles out of the way rather than attach themselves to you. Washing clothes and showering to disinfect is said to be necessary only when actually spending time looking after a COVID infected person, not necessarily after just visiting a grocery store. But hand-washing with soap and water is essential. Not an expert here – just quoting reasonably reliable sources (CBC News). My own practice is to wipe my hands with hand sanitizer after I get back in the car from any public place, and then wash thoroughly at home.
Agree. And to piggyback on this, 6 feet is roughly the distance between you and another adult if you stretched out your arms toward one another - pretty easy to eyeball.
If the OP is looking for something more scientific, I would gather the scientists are not sure, either, but giving a general guideline that seems decently effective and easy to remember now is better than waiting for rigorous studies that may give a more precise measurement of risk later.
The CDC uses the exact phrase, “Stay at least 6 feet (2 meters) from other people” on their recommendation list.
They aren’t exactly equal, but for the three countries in the world that are still not on the metric system, we need to use a measurement people can relate to. For the rest of the world, use the metric system. Based on some checking I’ve done, WHO is recommending 1m (3 feet). Again, they aren’t exactly equal, but the point is to put it in a unit that someone can easily relate to.
So, where did this recommendation come from? What about the rest of the questions? The argument about whether 6’ and 2m are effectively the same for social distancing is missing the point. As I said, there was an interview with Dr. Ko from Yale who said it was determined from looking at the infection transmission from an infected airline passenger.
His comment in the interview is that people 2 rows ahead (around 6’) were getting sick. He wasn’t saying 6.00000001 feet.
I’ve heard other talk about droplets and how far they travel before falling to the ground.
I don’t know how to track down whatever research Dr. Ko referenced when he talked about using the airline data. I don’t know what data was used in measuring droplet distance, although I have heard some of that research is a bit under question. That is why I wondered what people here knew and could point to. It really does not matter if 6’ is exactly 2m, or 3’ is exactly 1m. These are recommendations that are being made by scientific organizations and I’m curious as to their origin, if known.
Part of the origin question goes into trying to determine if that 6’ or 3’ recommendation is a circle or semi-circle. I just don’t see how someone can spray droplets, especially from just talking, 3’ behind them, let alone 6’. I’m also curious if I’m outside somewhere and someone is passing by me, maybe going the other way, does it do me any good to turn away from them. If they 6’ circle idea is to be believed, it wouldn’t.
You may not realize just how far tiny particles can travel in the air when you sneeze, cough, or even talk. NBC’s Kerry Sanders takes an in-depth look at the science behind the 6-foot social distancing rule.
The take is that 6 feet is probably OK but not a guarantee.
Unless I am doing it wrong, I don’t think it was meant to be a floating six foot barrier at all times. It is really impractical in places like the grocery store. What I, and others, seem to be doing is that if you are standing still in a spot, you make sure to stop six feet from others. If you are going down a store aisle, though, people will walk right past you, which I think is okay because the time of contact is very minimal. But if someone is standing at the beer cooler, let’s say, in front of your favorite brand of beer, then you stop six feet away and wait for them to move before you go browse that item.
I think it would be impractical and require a large amount of coordination to maintain and absolute six foot barrier around everyone at all times.
Of course there is no number where transmission suddenly becomes impossible. It is all about probabilities…and the farther away, the smaller the chance of transmission.
Seems like some people didn’t learn about significant digits in school? 6 ft is equal to 2m within the implied precision. If the difference mattered, the guidance would have said 6.0 ft or 2.0 meters.
I feel like this is kind of directed at me, in an unfriendly and unhelpful way. I mentioned the difference because I’m interested in how they came up with the number in the first place, not because I’m confused about significant digits.
Look, maybe I’m just having a bad day, but I really don’t enjoy being put down. By all means fight my ignorance if you think I’m misunderstanding something, but please at least try to be decent about it.
I think the answer is that in many times in life we use arbitrary numbers for ease of enforceability, compliance, and for the knowledge of the public.
For example, there is nothing magical or scientific about 70mph as being the speed limit. 71 or 69 would be equally as good, but we pick a nice round number. Just like there is nothing that makes you mature enough to buy alcohol the day after your 21st birthday any more so than you were the day prior to it, but there is the law—and unique in and of itself. It’s not a round number like 20 or 25? It’s because some guy picked 21 as the age of majority hundreds of years ago.
But it has predictability. I don’t have to guess if I am in compliance with the law. Even if it is arbitrary, I know that the day before I’m 21, it is illegal for me to drink, but the day after, I’m good. Police can easily enforce it in the same way.
We pick 6 feet in this example because it complies with most of the science we have and it is well known enough that people can picture it.