And already numerous videos - mostly little scientifically empirically comprehensible experiments - of breathing or sneezing people can be found. The results of these observations often have no further value, since the physics behind them is dubious and no meaningful measures can be derived from them. Legislators cannot assess whether corona viruses are spread around the room by hand dryers or whether the effect of a door opening is greater. It is up to companies to provide evidence that their equipment - whether ventilation systems or hand dryers - is safe. Real trials, however, are costly, and evaluating the results is difficult.