In which situation would hand sanitizers be ineffective?

Hand sanitizers are designed to kill germs and bacteria on the skin, but their effectiveness is significantly reduced when hands are visibly dirty or greasy. This is because the presence of dirt, grease, or organic material can create a physical barrier, preventing the hand sanitizer from effectively making contact with the skin and the pathogens it aims to eliminate. Therefore, it is essential to wash hands with soap and water in such situations to ensure that all contaminants are removed, allowing for better sanitation before using hand sanitizer.

In public restrooms, applying skincare products, and during facial treatments, hand sanitizers can generally be effective, provided that the hands are clean.