I thought about this question in the middle of this video.
Ok, Thioacetone takes the price for the World's smelliest chemical, I can accept it (why not?), but what about
You can smell one drop of this substance, almost instantly, from half a kilometer away
I'm an aerospace engineer, so I know pretty much about transport phenomena, but maybe I miss something about the kinetic theory of gases...
As far as I know, how far can I smell a substance depends on:
- how much substance there is,
- how good my nose is at detecting that kind of molecules (the substance),
- how favorable a lot of factors are for that molecules to actually reach my nose!
In the third point, by "a lot of factors" I mean temperature, density, ..., and, most importantly, convection! If the winds takes that molecules away from me, or if it just doesn't take them towards my nose, it doesn't matter how much substance there is and how good my nose is, does it?
The only thing I can think of that supports the quoted sentece is that despite fluid particles are not macroscopically driven to my nose (because driven away by wind or not driven at all by steady air), some molecules could still reach it thanks to their individual velocity.
Will they? I mean, in a drop there are many many molecules (order of 10 to the... let's say 15, shouldn't be far from reality), but they will still simply hit sourrounding air molecules (which should be not far from the same in number per cube centiemter), just like any other gas.
So what am I missing?