If you are smelling perfume from a person then you are not smelling droplets. You are smelling the vapour from the perfume - some of the molecules of the aromatic compounds which were left on the person's skin after they sprayed or dabbed the perfume on and which are slowly evaporating.
Hi Guys
When out walking, it is quite common to be able to smell perfume from a distance of 10m from the wearer.
This makes me think that Covid particles must be heavier than perfume by a factor of 5 (if you accept the government's 2m rule as valid).
Or is there another factor that plays into the airbornness of perfume and Covid particles.
Phil
"Since then, respiratory diseases have been divided into those transmitted via droplets (usually from close contact) and those that are airborne and can spread over longer distances, such as measles or tuberculosis."
"Does it mean that COVID-19 is spreading from person to person through aerosols? I would say definitively not," Loeb said.
"The reason we know that is because all around the world we have hundreds of health-care workers who are taking care of patients wearing regular masks," she said. "If this were airborne - if this were usually in those small [aerosol] particles ? all those health-care workers would be getting sick." "
If this were measles-like, we'd be using entirely different rules.
Part of what you're doing, is keeping your distance from super-spreaders.
When some barber shop employees got COVID, none of their customers got it, because (amongst other things) mask policy.
The chick with the perfume might be a proxy for measles, but not for COVID. She would be indicative of "how careful you'd need to be to avoid measles".
Paul
Same for cigarette smoke too.
A perfume molecule is typically some sort of cyclic aromatic molecular weight around 80-300 amu. Some lighter and some much heavier.
A virus is a mixture of RNA and protein and very much heavier. The ratio of their typical masses is more like 10^6 (back of envelope) (just for a single fragrance molecule and single virus particle)
Infective Covid particles are much heavier than that typically being in a water aerosol with around 1um radius. They still float in the air for a very long time which is why they are trouble in a confined space.
A typically infective aerosol droplet would be another 10^5 times heavier still but that is still only of the order of 1pg (tiny).
These things are all so light that they drift in the air.
Brownian motion (no relation) jostles very small particles and keeps them aloft for quite a while as do air currents. When the medics talk of airborne transmission they mean these fine invisible aerosols rather than visible sized droplets spray that you can see with visible light.
Individual virus particles have to get very lucky to infect you. The probability of any one being successful is around 0.1% so when you get exposed to around 700 then your odds are 50:50 for catching it. Give or take a factor of three either way - no challenge tests have been done.
You could be very unlucky and catch it from a single virus but our innate immune systems defences are really rather good otherwise we would be succumbing to all sorts of opportunistic diseases (as happens to people whose immune systems are compromised).
I think Leob is incorrect. Aerosol transmission is now well documented, and ventilation guidance is now pretty standard in all risk assessments.
They are. Depending on the context, much more likely to become infected, and
7x more likely to suffer severe symptoms.The danger with generalising from one case is that . . . it doesn't work, especially with new variant(s) appearing. We simply don't know at this point.
like me
Its all in the size of the droplets. Perfume is I think often based on some substance that evaporates, and hence is not going to be carrying virus. However coughs and exhalations when speaking do give off larger droplets, and a mask slows these down so they fall faster. That is why it need not be a surgical mask, you are just trying to slow down the air. Brian
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