How Do Hand Sanitizers Work?

Hand sanitizers work by stripping away the outer layer of oil on the skin. This usually prevents bacteria present in the body from coming to the surface of the hand. However, these bacteria that are normally present in the body are generally not the kinds of bacteria that will make us sick. In a review of the research, Barbara Almanza, an associate professor at Purdue University who teaches safe sanitation practices to workers, came to an interesting conclusion. She notes that the research shows that hand sanitizers do not significantly reduce the number of bacteria on the hand and in some cases may potentially increase the amount of bacteria. So the question arises, how can the manufacturers make the 99.9 percent claim?
How Manufacturers Make the 99.9 Percent Claim

The manufacturers of the products test the products on bacteria-tainted inanimate surfaces, hence they are able to derive the claims of 99.9 percent of bacteria killed. If the products were fully tested on hands, there would no doubt be different results. Since there is inherent complexity in the human hand, testing hands would definitely be more difficult. Using surfaces with controlled variables is an easier way to obtain some type of consistency in the results. But, as we are all aware, everyday life is not as consistent.