[EvaH (OP)]

Pauls asks:

If the virus lasts for several hours in the air, this means if you are walking behind someone (even 2 metres apart) the wind could still carry a virus back to you. Even if the virus falls to the ground you could walk over it and carry it home. Furthermore if you have a cat or dog who walks into the house behind you, it could pick up the virus, and deposit it on a settee so when you sit down, after washing your hands, your hand comes in contact with the virus and voila, you have the virus.

What do you think?

[Petrochemicals]

I think it dries out in any form that can become blown by the wind. Viruses die when dried out, corona is known not to be able to survive this environment

[Colin2B]

If the virus lasts for several hours in the air, this means if you are walking behind someone (even 2 metres apart) the wind could still carry a virus back to you. Even if the virus falls to the ground you could walk over it and carry it home. Furthermore if you have a cat or dog who walks into the house behind you, it could pick up the virus, and deposit it on a settee so when you sit down, after washing your hands, your hand comes in contact with the virus and voila, you have the virus

The SARS-CoV-2 virus has a viable half life of 1hr in air and has been detected up to 3hrs, so it is possible to contract the virus by breathing it in as you suggest. The likelihood of infection depends on the amount inhaled and it disperses rapidly in any wind. Keep upwind of people and avoid anyone likely to generate more droplets - someone coughing, runners etc.
Picking it up on shoes is very unlikely to bring viable virus into the house and most people change from outdoor shoes when entering the house which reduces even that very small risk.

[vhfpmr]

To stop an epidemic you just need to reduce R below 1, and to do that, it's sufficient to reduce the risk, not eliminate it altogether. Addressing the major risks is the most cost efficient way, dealing with a multitude of minor risks is expensive and ineffective. (See Pareto principle)

[evan_au]

the wind could still carry a virus back to you

A wind is generally turbulent (around trees, houses, etc).
This not only carries virus particles horizontally, it also moves them vertically.
This reduces the concentration of virus particles considerably - they are no longer concentrated in a thin band at head height, but spread over hundreds of meters vertically.
Indoor has no wind, but a typical ceiling height of 2-3m means that the concentration of virus particles remains high - especially if the windows are closed.