> to hear people complain that walking near a smoker on a sidewalk outside is a risk to their health

Doesn't have to be the smoke itself that's harmful. Presumably, if you can smell someone's second-hand smoke, you're also inhaling the bacterial spray contained in their breath, no? Something I think about if I'm walking outside without a mask on and end up stuck walking for a while behind a smoker. I tend to put my mask back on.