Alcohol hand rubs are intended for use on hands that are:

Alcohol hand rubs are specifically formulated for use on hands that are not visibly soiled. This is important because alcohol-based hand sanitizers are effective at reducing the number of germs on the skin, but they are not as effective when hands are contaminated with dirt, grease, or organic matter. In such cases, washing hands with soap and water is recommended to physically remove the soil and any pathogens present.

Using alcohol hand rubs on visibly clean hands allows the alcohol to effectively reduce the microbial load, facilitating fast and efficient disinfection. For optimal effectiveness, it's essential that hands be free of any visible contamination to ensure that the alcohol can work properly and to maximize its germicidal properties.