My notion of the day is that smoke inhalation is a decent metaphor for coronavirus. This is because of the concepts of toxic dispersion and viral load. In other words, it does not matter if one encounters a few viral bits, but rather if enough bits are present to overwhelm the normal filtering defenses of the body.
Think of smoke outside. You hardly notice smoke from a campfire unless you are sitting right on top of it for a while. Even being near a forest fire hardly matters, although the air quality declines. One rarely hears of a person dying from smoke inhalation while they are in a field.
Inside, it is a different story. Smoke is trapped depending on ventilation and size of the room, and quickly becomes lethal. A bandana or towel (mask) may help for a while, but eventually it is useless and only the rescue equipment worn by first responders is effective.
Think of infected people as campfires, some very smoky, some less so. The rest of us go about with or without bandanas, near them or further away, rarely affected by smoke outside, but potentially stricken by being near them for a while in close quarters, somewhat like death from carbon monoxide poisoning. These people may put blankets over their own fires, but this is only partially effective.
And finally, to stretch the metaphor perhaps a bit too much, think of age as height. Those breathing air higher up in a room will be more affected than those (like children) near the floor. And, of course, a lot depends on the state of your lungs.