Alcohol-Based Hand Rub (ABHR) is an alcohol formulation, often a gel, foam, or liquid, designed to rapidly reduce microorganisms on the hands. ABHR is the preferred method for routine hand sanitation when hands are not visibly soiled. Failure to use the appropriate quantity is one of the most frequent reasons for inadequate hand disinfection. The correct dose ensures the alcohol contacts the skin surface for the necessary duration to be fully effective.
Establishing the Standard Dose
The standard measurement for effective ABHR application is the volume needed to wet all surfaces of the hands. Health organizations recommend an application volume of approximately 3 milliliters (mL) for adults. This volume is based on clinical efficacy studies designed to ensure proper antimicrobial contact time. Using a smaller amount, such as 1 mL, is substantially less effective than the standard 3 mL dose.
A simple way to visualize this standard is by dispensing “a palmful” of the product. This amount should fill the cup of the palm sufficiently to be spread across both hands. Since many dispenser pumps provide between 1.5 mL and 2 mL per actuation, two pumps are often necessary to reach the recommended volume. Users frequently apply suboptimal amounts, often less than 1 mL, which is a common barrier to adequate hand hygiene.
Visualizing the Correct Amount for Full Coverage
The true metric of correct dosing is not the volume itself, but the outcome it achieves: complete hand coverage for the required duration. The primary goal is to ensure the product keeps the hands wet for the entire duration of the necessary rub time, typically between 20 to 30 seconds. If the alcohol rub dries on the hands sooner than this benchmark, the initial dose was insufficient to achieve full efficacy.
A volume of 3 mL results in almost complete coverage of the hands, whereas smaller volumes, such as 1.5 mL, often leave significant areas unreached. The product must be visibly present on all areas of the hands throughout the rubbing process. Complete coverage ensures that all transient microorganisms are exposed to the alcohol for the time needed to neutralize them. Often-missed spots that require coverage include:
- The backs of the hands.
- The areas between the fingers.
- The thumbs.
- The fingertips.
Factors That Modify the Required Dosage
While 3 mL is the widely accepted standard, several factors may necessitate a deviation from this dose. Unusually large hands will require a slightly increased amount of ABHR to ensure all surfaces remain wet for the full 20 to 30 seconds. The surface area of the hands directly influences the amount of product needed to maintain wetness until the required dry time is met.
The physical form of the product can also affect the required dose, as gels and liquids spread differently across the skin. While ABHR is generally ineffective on visibly soiled hands, if it is the only option available, a significantly larger amount may be necessary to attempt to carry away debris. For visible soiling, switching to soap and water is the preferred and most effective method. Some modern, high-alcohol formulations may achieve efficacy with slightly lower volumes than traditional products, but only if they are tested to meet the same standards.