This article has info all in one place. It was already excerpted when I saw it; I assume that is what the elipses are.
"The Risks - Know Them - Avoid Them" by Professor Erin Bromage, Comparative Immunologist and Professor of Biology (specializing in Immunology) at the University of Massachusetts Dartmouth.
The main sources for infection are home, workplace, public transport, social gatherings, and restaurants. This accounts for 90% of all transmission events. The biggest outbreaks have been in enclosed environments with poor air circulation and high density of people. These have included prisons, religious ceremonies, group-living situations, and workplaces such as meat-packing facilities and call centers. I regularly hear people worrying about grocery stores, bike rides, inconsiderate runners who are not wearing masks ... are these places of concern? [ ]
In order to get infected you need to get exposed to an infectious dose of the virus[.]
[You can get infected by:]
[Touching things in a b]athroom: Bathrooms have a lot of high-touch surfaces, door handles, faucets, stall doors. Transfer risk in this environment can be high. We ... do not know whether a person releases infectious material in feces or just fragmented virus, but we do know that toilet flushing aerosolizes many droplets. Treat public bathrooms with extra caution (surface and air), until more is known about the risk.
A cough: A single cough releases about 3,000 droplets, and droplets travel at 50 miles per hour. Most droplets are large, and fall quickly, but many stay in the air and can travel across a room in a few seconds.
A sneeze: A single sneeze releases about 30,000 droplets, with droplets traveling at up to 200 miles per hour. Most droplets are small and travel great distances (easily across a room). If a person is infected, the droplets in a single cough or sneeze may contain as many as 200,000,000 (two hundred million) virus particles, which can all be dispersed into the environment around them.
A breath: A single breath releases 50 - 5000 droplets. Most of these droplets are low velocity, and fall to the ground quickly. There are even fewer droplets released through nose-breathing. Importantly, due to the lack of exhalation force with a breath, viral particles from the lower respiratory areas are not expelled.
All you have to do is enter a room within a few minutes of a cough/sneeze and take a few breaths and you have potentially received enough virus to establish an infection.
With general breathing of 20 copies [of the virus] per minute into the environment, even if every virus ended up in your lungs, you would need 1000 copies divided by 20 copies per minute: 50 minutes [of exposure].
Speaking increases the release of respiratory droplets about 10 fold; ~200 copies of virus per minute. Again, assuming every virus is inhaled, it would take ~5 minutes of speaking face-to-face to receive the required dose.
Anyone you spend greater than 10 minutes with in a face-to-face situation is potentially infectious [or could get infected by you].
It appears approximately 40% of all infections -- and the majority of community-acquired transmissions -- have occurred from people without symptoms (asymptomatic or pre-symptomatic people). You can be shedding the virus into the environment for up to 5 days before symptoms begin.
Social-distancing rules are to protect you with brief exposures, or outdoor exposures. Social-distancing guidelines don't hold in indoor spaces where you spend a lot of time, as people on the opposite side of the room have gotten infected.
If you are in an open-floorplan office ... critically assess the risk (volume, people, and airflow). If you are in a job that requires face-to-face talking or even worse, yelling, you should assess [whether the risk is worth it to you].
Even if gung-ho for resuming business as usual, do your part and wear a mask to reduce what you release into the environment.
Infected respiratory droplets land somewhere. Wash your hands often and stop touching your face.
The only people who have most cause to fear it are those who have health problems and over 60 - if you check who has died by looking at the graphs. Most people are not going to die even if they get it. Most vulnerable are over 60s with co-morbidities, obese and people in Care Homes! Plus it isn't going away until they have a vaccine. So we will all have to get used to the risk. Looks like it is going to be another flu. True it has killed some few people and they don't know why yet. More people die of Dementia and Cancer every single year, and heart disease.
I'm not sure that's true that the most contagious cases are those gasping for breath, asymptomatic people quite possibly are spreading it the most since nobody knows they are sick. But that being said, let's look at this particular instance. Both of you were wearing masks. Masks actually aren't all that protective for you but they protect others from you, and he was wearing a mask and so were you. Second, you were beyond the 6 feet we're recommended to social distance. You don't say if you were outdoors or not, but it's much harder to get it outdoors so if you were that's another safety factor -- it spreads best in crowded indoor places where air circulation isn't all that great. Outdoor air also pushes any droplets down rather than out. He also doesn't appear to have been either facing you or coughing. And most important, it takes a fairly intense encounter for most people to get it -- not a very brief one. Don't add anxiety to the already bad situation with this virus if you can help it. Peace.
As you told you were wearing a mask, you didn't touch him and you were standing 10 feet away. There are no chance of getting the virus.
Being near someone who is heading for a Covid-19 test is more likely to mean nothing than something, because a lot of people who get tested don't wind up having Covid-19.
But even if the person you were suspicious of really did have Covid-19, you are still pretty safe. Here are some reasons:
- He was masked.
- You were not standing close to him.
- He was facing the security guard, not you, when he talked.
- Apparently he was not coughing.
- The most contagious cases are not those walking in and calmly asking the security guard where the testing is, they are those rushed in by ambulance gasping for breath.
It doesn't sound like you had any exposure.
Stay careful, try not to freak out.