Time - minimize duration of contacts
Distance - physical distancing
Shielding - masks and barriers
* Radiator is people's noses and mouths not x-ray machine
* Like most x-ray machines, radiation is not uniform in all directions - focus on nose and mouth
* For COVID 19, a thin layer of cloth is very effective shielding. X-rays need heavy lead shielding
* Like radioactive sources, assume they are active at all times - in other words assume everyone is infected for the purposes of when to use time-distance-shielding
This doesn't mean accepting no risk, or ignoring all trade offs.
nrc.gov/about-nrc/radi…