Healthy people should never wear a mask. Children should never wear a mask. The standard of care in a hospital is to wear a sugical type mask no longer than three hours and then it must be changed. Today we have people wearing "designer" masks of cloth, wearing masks for a long day at work or school, then wearing the same mask after work or school and wearing the same mask day after day. They also touch their mask repeatedly with contaminated hands. Most people toss their mask onto a car seat, stuff it in a pocket, a purse etc. further contaminating the mask.