Hand washing with soap and water is the recognized first step in preventing the spread of germs. However, it represents only half of the hygienic process; the final step is the thorough drying of the hands. Optimal hand hygiene is not achieved until all residual moisture is removed. The method chosen for drying is just as important as the washing itself.
The Critical Role of Hand Drying in Hygiene
Hand drying is critical because moisture acts as a vehicle for microbial transfer. Wet hands transmit pathogens much more readily and efficiently than dry hands to surfaces and other people. Studies show that damp hands can spread up to 1,000 times more bacteria than completely dry hands. Using a quick, ineffective drying method significantly undermines the benefits of a proper wash.
Residual water on the skin’s surface provides a conducive environment for remaining microorganisms to survive and thrive. The friction of damp hands against surfaces allows for easy and rapid exchange of germs. Therefore, the primary goal of any hygienic drying method is to reduce the microbial load on the skin by achieving a high degree of dryness quickly.
The Science of Physical Removal (Paper Towels)
Single-use paper towels offer a dual-action mechanism that is highly effective for hygiene. First, the towel fibers immediately absorb the water remaining on the skin after washing, addressing the moisture-as-vehicle problem. This action alone substantially reduces the environment available for microbial survival and transfer.
The second action is mechanical removal, achieved through the friction of the paper against the skin. As the hands are wiped, the towel physically dislodges and lifts off residual bacteria that were loosened during washing. This mechanical scrubbing further reduces the number of microorganisms on the hands.
Scientific studies consistently show that paper towels reduce the number of bacteria on the hands after use. The technique of patting or lightly rubbing the hands is a key component, as the friction removes remaining microbes. Furthermore, because paper towels are immediately discarded, they minimize the risk of environmental contamination within the washroom.
Evaluating Airflow Drying Technologies
Airflow technologies, including warm air dryers and high-speed jet air dryers, operate on different principles than paper towels. Traditional warm air dryers rely on evaporation, using heated air to turn water on the hands into vapor. High-speed jet dryers use focused, high-velocity air jets to physically shear the water off the hands.
The primary hygienic concern with both types of air dryers is their potential to aerosolize microbes. Instead of removing bacteria, the force of the air blows water droplets containing microorganisms into the surrounding air and onto other surfaces. This action can contaminate the user, bystanders, and the washroom environment.
Research demonstrates that jet air dryers are particularly problematic, with some studies finding they can disperse microbe-containing droplets up to 3 meters away. The high-speed airflow can spread particles up to 1,300 times more than paper towels. The microbes can remain airborne for several minutes, settling on surfaces or being inhaled by others.
While some studies find that air dryers can be equally effective at reducing bacteria if hands are held stationary for a long time, user behavior often complicates this finding. The typical short drying time used by the public frequently results in incompletely dried hands, maintaining a high risk of microbial transfer. Consequently, paper towels are considered superior due to their ability to physically remove microorganisms and contain them, rather than dispersing them into the environment.