Alcohol concentration is not the higher the sterilization effect is better. Generally speaking, 75% of alcohol sterilization effect is the most ideal, mainly because this concentration of alcohol has a good permeability. It can effectively penetrate into the bacteria, absorb the water of the protein in the cell, make it dehydrated, protein coagulation, to achieve the effect of killing bacteria. But when the alcohol concentration increases after its permeability gradually reduced, although the high concentration of alcohol on the cell wall has a very good destructive, but the high concentration of alcohol can be a large number of bacteria or other impurities coagulation, can not penetrate the coagulation of impurities wrapped in other bacteria inside. When the alcohol evaporates, the bacteria inside the coagulated impurities will reproduce again. Therefore, high concentrations of alcohol are not suitable for sterilization and disinfection, and 75% alcohol with better penetration is suitable for use during disease epidemics or in routine preventive work.