you don't need to keep perfect distance everywhere. transmission risk, at an individual level, is a function of both time and (the inverse of) distance[0]. if d

you don't need to keep perfect distance everywhere. transmission risk, at an individual level, is a function of both time and (the inverse of) distance[0]. if distance is short and time is short, as at the grocery store, risk is still miniscule. if distance is short and time is long, which is the likely case for social interactions in private spaces, then risk rises, which is why that's the place where masking can have some mitigative effect, but because social norms act against masking, that's where most transmission happens, not between strangers (outside of care settings and social-focused venues). airflow is at best a second-order (and probably weaker) effect, but volume (e.g., outdoors) dominates it because volume multiplies the effects of both time and distance. in a similar vein, at the office, only large meetings are really a potential problem (for which you can mask or teleconference), but not appropriately-spaced meetings or sitting at a desk with appropriate distance to the next person. for retail workers in potentially close contact with a large number of the public daily (time elongated through multiple people), then a mask can have mitigative effect, but patrons can just distance from each other. [0]: note also that the virus decays as a function of time, on the order of minutes outside the body.