Not OP, but I had the same theory but with cigarettes. According to Google results, cigarette smoke particles are 0.25 micron at the largest, Sars-CoV-2 virus is 0.12 micron, so about half. They're both so light that gravity probably has little effect.

So, sharing a room with someone sick probably gives you a high chance of encountering the virus, but outdoors one hopes the concentrations would be so low that our bodies can fight it off.

And if you're wearing a mask and can still smell cigarette smoke, then surely it means that mask would let the virus particles through as well.

And in fact, this is how you test the respirator fit in professional setting. You don your respirator, and then somebody sprays a funny-smelling substance. If you can smell it, it means it doesn't have a proper seal on your face.