Traditional handwashing with soap and running water remains the gold standard for hygiene. However, these resources are often unavailable during travel, hiking, or while running errands. In these situations, quickly reducing the presence of microbes on the hands is necessary to prevent the spread of illness. An effective alternative is the waterless method, which can be carried easily and helps maintain cleanliness when proper washing facilities are inaccessible.
The Go-To Solution: Alcohol-Based Hand Rubs
The most effective waterless cleaning method is the use of an alcohol-based hand rub, or hand sanitizer. For reliable effectiveness, these products must contain an alcohol concentration between 60% and 95% by volume. A minimum of 60% ethyl alcohol or 70% isopropyl alcohol is often cited. Alcohol works by rapidly denaturing proteins in the outer coats of bacteria and certain viruses, causing the microbe to lose its structure and become inactive.
Water aids in this denaturation process, which is why alcohol concentrations above 95% can be less potent. Alcohol-based rubs are effective against a broad spectrum of organisms, including most bacteria and viruses with a fatty outer layer (envelope). Non-alcohol sanitizers, such as those using benzalkonium chloride, do not offer the same broad-spectrum activity and are not the standard recommendation.
Applying Sanitizer Correctly for Maximum Effect
The effectiveness of an alcohol-based hand rub depends significantly on the application technique and the amount used. Apply enough product to thoroughly wet all surfaces of your hands, typically a generous squirt or palm-full. Immediately after dispensing the sanitizer, rub your hands together vigorously. Ensure the liquid makes contact with the palms, the back of the hands, the areas between the fingers, and the fingertips.
Covering all areas, including the thumbs and under the nails, is important as these areas can harbor microbes. Continue rubbing until the product has completely dried on your skin, which usually takes about 20 seconds. Allowing the product to air-dry naturally ensures the alcohol remains in contact with the microbes long enough for inactivation. Do not wipe the sanitizer off or rinse your hands before they are fully dry, as this compromises the product’s effectiveness.
When Waterless Methods Are Insufficient
Alcohol-based hand rubs have specific limitations that make soap and water mandatory in certain situations. The primary limitation is when hands are visibly dirty, greasy, or contaminated with heavy grime, such as after gardening or handling raw meat. Alcohol cannot effectively penetrate thick layers of dirt or organic material, shielding the microbes underneath from the sanitizing action.
Alcohol is also not effective against all types of pathogens, specifically those that lack a protective lipid envelope. Non-enveloped viruses, such as Norovirus, are particularly resistant to alcohol-based products. Similarly, the spores of bacteria like Clostridioides difficile (C. difficile) are not reliably killed by hand rubs. In these scenarios, the physical action of washing with soap and water is necessary to remove the resistant organisms from the skin’s surface.