well ventilated environment 6 feet of separation is pretty good if everybodys got a mask on and nobody stays directly downwind of an infected person for very long says dr donald milton of the university of maryland school of public health whose lab houses the gesundheit ii machine duration of exposure is important so theres probably not much risk from a short elevator ride while masked or being passed by a jogger on the sidewalk experts say scientists have published online tools for calculating risk of airborne spread in various settings at a recent meeting on aerosols however dr georges benjamin executive director of the american public health association noted that preventive steps can be a challenge in the real world keeping apart from other people can be difficult in homes that house multiple generations some old buildings have windows that were nailed shut years ago he said and we have far too many communities where they simply dont have access to clean water to wash their hands it might seem strange that for all the scientific frenzy to study the new coronavirus the details of how it spreads can still be in doubt nine months later but history suggests patience weve been studying influenza for 102 years says milton referring to the 1918 flu epidemic we still dont know how its transmitted and what the role of aerosols is