Handwashing is recognized as the primary defense against the spread of germs and infectious disease. However, washing with soap and water only represents half of the complete hygiene process. Hand drying is a distinct, non-negotiable step that finalizes the hygienic routine. If hands are not thoroughly dried afterward, the physical removal of pathogens is significantly undermined, preventing the transfer of microorganisms.
Why Drying Hands is Essential for Health
Residual moisture remaining on the hands is the most important factor determining microbial transfer after washing. Wet hands are far more likely to pick up and spread bacteria and viruses than dry skin. Damp hands can spread up to 1,000 times more bacteria than completely dry hands.
Water acts as a bridge, allowing any remaining pathogens to easily translocate from the skin to any surface touched, such as doorknobs, food, or other people. Thorough drying prevents this transfer by eliminating the moisture that facilitates germ mobility. Proper drying can reduce the transfer of bacteria to surfaces by an order of 99%.
Drying also serves a dual purpose by physically removing residual microorganisms left behind after washing. The mechanical action of drying, particularly with an absorbent material, physically lifts and removes bacteria from the skin surface. If hands remain damp, not only do they spread germs more readily, but the moisture itself can contribute to skin irritation and breakdown, which allows for increased colonization of bacteria.
Comparing Hand Drying Technologies
The three primary methods for hand drying—paper towels, warm air dryers, and high-speed jet air dryers—each function differently, leading to varied levels of hygienic performance. Paper towels rely on absorption and friction, consistently offering superior results from a public health perspective.
Paper Towels
Disposable paper towels are highly efficient, quickly reducing residual water within 10 to 15 seconds. This process involves a mechanical abrasive action, where the towel’s fibers physically strip dislodged bacteria from the skin along with the moisture.
Warm Air Dryers
The traditional warm air dryer, which uses heated air to evaporate water, is generally the least effective method. These devices are slow, often requiring 30 to 45 seconds of use to achieve a dryness level comparable to that of a paper towel. Furthermore, rubbing hands together under the warm air can be counterproductive. This friction may cause bacteria residing deeper in the hair follicles and skin layers to migrate to the surface, potentially increasing the number of culturable organisms released.
High-Speed Jet Air Dryers
High-speed jet air dryers use a high-velocity sheet of air to shear water from the hands, drying much faster than warm air models, often within 10 to 12 seconds. While quick, this method presents a hygienic risk: the potential for microorganism dispersal. The powerful airflow can aerosolize any lingering bacteria or viruses from the hands and blow them into the surrounding environment, potentially contaminating the air and nearby surfaces.
For these reasons, particularly in settings where infection control is a high priority, such as healthcare facilities, single-use paper towels are widely recommended over air drying systems. They offer the most effective combination of rapid moisture removal and bacterial reduction without contributing to environmental dispersal of germs.
Maximizing Drying Effectiveness: Proper Technique
Regardless of the method available, maximizing drying effectiveness begins with removing excess water immediately after rinsing. A brief, gentle shake of the hands at the sink can significantly reduce the moisture load, minimizing the time needed for the next step.
When using paper towels, the optimal technique involves a patting or blotting motion rather than aggressive rubbing. Start by drying the wrists and palms, working down to the fingertips, paying specific attention to the areas between the fingers and underneath the nails where moisture can collect. If the towel dispenser is not touchless, use the final piece of dry paper towel to turn off the faucet and open the restroom door to avoid recontaminating the clean hands.
If an air dryer is the only option, resist the urge to rub your hands together vigorously while under the flow, especially with older, warm air models. This action can mobilize bacteria from the skin’s deeper layers, negating the positive effect of washing. For high-speed jet air dryers, follow the manufacturer’s recommended motion, which usually involves slowly drawing the hands through the air column from the wrists to the fingertips. Keep hands flat and slightly cupped to allow the air to reach all surfaces until they are completely dry to the touch.