Alcohol 75% is the most commonly used concentration of alcohol for medical or clinical purposes, and this alcohol can be used directly for disinfection of skin surfaces, or for disinfection of objects or air. Generally speaking, medical alcohol can be used directly without dilution, sprayed with a spray bottle, or dipped in a paper towel or rag and wiped on the surface of the object. Another concentration of alcohol is 95%, generally speaking, is not used for disinfection, but for the use of fuel for scientific alcohol lamps. If 95% alcohol is used for disinfection, it must be diluted, because too high a concentration of alcohol will cause the surface proteins of the virus to coagulate and lose the effect of killing the virus.