INDIVIDUAL PARTICIPATION is infentiisimal compared to well thought government strategy. ventilation of buildings design of buildings to deal with viral infection etc.. is just as important as wearing a mask[a mask that may have been handled or dirty etc ]

Most public buildings put up in the last generation have terrible air circulation when aerosolized pathogens are the issue. The timescale we are dealing with is months, not decades. Masks can work that fast, rebuilding can't.