顺序是：洗手 — 烘干 — 喷消毒剂，而不是洗手 — 喷消毒剂 — 烘干。

如果去掉中间的烘干步骤，手上残留的水分导致消毒剂70%乙醇的浓度被稀释，杀菌能力降低。

70%乙醇的杀菌原理，以及为什么不能使用过高或过低浓度的乙醇溶液杀菌的原因如下：

For our experiments we are using seventy percent to sterilize surfaces here at science world. Why is it not 100% or 50%? This has to do with the process by which it kills microorganisms. It works by denaturing their proteins and dissolving their lipids. The water in the ethanol solution is the portion that actually does the denaturing. Using higher concentration makes the ethanol less effective because there cells cannot be denatured by the water. Lower concentrations do not allow the ethanol to be as effective because it can not break down the all lipids or allow the water to get into the cells.