Alcohol-based hand rubs are most effective when used on which of the following surfaces?

The effectiveness of alcohol-based hand rubs is maximized when they are applied to dry and clean surfaces. This is because alcohol needs to evaporate to efficiently kill germs and bacteria, and moisture can dilute the alcohol, reducing its efficacy. Clean surfaces allow for better penetration and interaction with microorganisms, ensuring that the alcohol effectively disrupts their cellular membranes.

When surfaces are dirty, greasy, or wet, the presence of contaminants can create a barrier that hinders the alcohol from coming into direct contact with pathogens, thus decreasing the overall antimicrobial action. Therefore, using alcohol-based hand sanitizers on surfaces that are specifically dry and clean ensures that they perform as intended, providing optimal germicidal action.