Alcohol-Based Hand Rubs (ABHRs) are a primary tool in routine hygiene, designed to quickly and effectively reduce transient flora on the hands. These formulations, which typically contain a concentration of 60% to 95% alcohol, work by denaturing the proteins of microorganisms, rapidly inactivating them. Understanding the appropriate volume is the first step toward ensuring the effectiveness of the rub in preventing the spread of microorganisms.
Standard Volume Recommendations
Health organizations frequently recommend a volume range of 2 to 3 milliliters (mL) for a single application. This measurement represents the quantity that clinical trials have shown to be effective in reducing the microbial load on hands.
Relatably, this volume should be enough to create a “palmful” when dispensed into a cupped hand. The goal is to apply a sufficient amount of product to thoroughly wet every surface of both hands. If the hand surface is not kept moist throughout the rubbing process, the alcohol cannot maintain contact long enough to fully inactivate the germs. The volume must be adequate to sustain the rub for the recommended duration.
Proper Application Technique
The application process is a systematic procedure designed to ensure the product reaches all parts of the hands. Begin by applying the recommended volume into the palm of one hand. The process of rubbing the product in must continue until the hands are completely dry, a duration that should take approximately 20 to 30 seconds.
The technique involves rubbing the product over all hand surfaces, starting with palm-to-palm, then the back of the hands, followed by interlacing the fingers. Specific attention must be paid to areas often missed, such as the thumbs and the fingertips, which harbor a high concentration of germs. The fingertips should be rubbed against the opposing palm to cover the area underneath the nails. The hand rubbing action creates friction, which helps distribute the product evenly until it evaporates.
Factors Influencing Volume
While a standard volume is recommended, certain variables may require a slight adjustment. Hand size is a significant factor, as larger hands need a greater volume of ABHR to achieve coverage. The goal of keeping all hand surfaces wet for the full 20 to 30 seconds is compromised if the product dries too quickly.
The formulation of the hand rub, whether it is a liquid, gel, or foam, can also influence the required volume. For instance, a highly viscous gel may spread less easily than a liquid spray, potentially requiring a slightly larger pump. Ultimately, the correct volume is the smallest amount that allows the user to perform the full application technique for the recommended duration until the hands feel dry.
Limitations of Alcohol-Based Hand Rubs
Despite their effectiveness for routine decontamination, ABHRs are ineffective at removing visible dirt or grease from the hands. When hands are visibly soiled, the grime can physically shield microorganisms from the alcohol, making mechanical washing with soap and water necessary to physically remove the contamination.
Certain types of pathogens are also highly resistant to alcohol-based products. Spore-forming bacteria, such as Clostridioides difficile (C. diff), are not inactivated by alcohol because it cannot penetrate the protective outer shell of the spore. Similarly, non-enveloped viruses like Norovirus exhibit poor susceptibility to alcohol. In these specific instances, washing hands with soap and running water is the preferred method, as the friction and rinsing action physically remove the resistant microbes from the skin.