Hand drying is the final, crucial step in effective hand hygiene. While washing removes microorganisms, residual moisture acts as a vehicle for the rapid transfer of remaining pathogens. Wet hands spread bacteria and viruses far more easily than dry hands, meaning a thorough wash is negated if hands are not dried correctly. The goal is to remove this moisture quickly and completely to minimize cross-contamination.
Physical Removal: Single-Use Paper Towels
Paper towels offer a dual-action mechanism for hand drying through absorption and physical abrasion. The material is designed to soak up water from the skin, effectively removing moisture that facilitates germ transfer. This absorption process makes the method highly efficient and quick.
The physical friction created by rubbing or patting the hands helps dislodge microorganisms that survived washing. Studies indicate this mechanical removal can reduce the bacterial load on hands by up to 77%. The single-use nature of the towel ensures that bacteria and viruses are immediately sequestered and removed from the washroom environment upon disposal.
Proper technique involves using the towel to gently pat the hands dry or rubbing them together to utilize friction for microbial removal. An important hygienic practice is to use the clean towel to turn off the faucet and open the restroom door before disposal. This step prevents immediate re-contamination of the hands from high-touch surfaces. Paper towels are considered a highly hygienic option due to their effectiveness in moisture removal and microbial reduction.
Forced Evaporation: Electric Hand Dryers
Electric hand dryers operate by forced evaporation, utilizing high-velocity air to remove water. The two main types are older, warm air dryers and newer, high-speed jet air dryers. Warm air dryers use gentle airflow and heat, often requiring 30 to 45 seconds for adequate dryness. Jet air dryers use a concentrated stream of unheated or slightly heated air at a very high velocity, achieving dryness faster, typically in 10 to 20 seconds.
Despite the improved drying speed of jet air models, a significant hygiene concern for both types is the potential for aerosolizing microbes. This high-speed air can blow microorganisms off the hands and into the surrounding air, potentially contaminating the washroom environment and other users. Research has shown that jet air dryers can disperse viral particles over a distance of up to 2 meters.
Studies have shown that jet air dryers dispersed over 1,300 times more viral particles than paper towels. Warm air dryers are also problematic, with evidence showing they can increase the bacteria count on hands by circulating microbes present in the restroom air.
Health Authority Recommendations for Acceptable Methods
Major health authorities acknowledge that the primary goal is complete hand drying, generally accepting both single-use paper towels and electric air dryers. The Centers for Disease Control and Prevention (CDC) states that both clean towels and air dryers are effective ways to dry hands. The consensus is that any method achieving thorough dryness is better than leaving hands wet.
In settings where hygiene is paramount, such as hospitals, food preparation areas, and healthcare facilities, single-use paper towels are often the preferred method. Scientific evidence demonstrating lower pathogen dispersal and higher residual microbial removal with towels contributes to this preference. The FDA Food Code, which governs food service establishments, lists the following acceptable provisions for hand drying at a handwashing sink:
- Individual disposable towels
- Continuous cloth towel systems
- Heated-air hand-drying devices
- Air-knife systems
While air dryers are technically acceptable, particularly newer models with High-Efficiency Particulate Air (HEPA) filters, paper towels remain the method of choice for minimizing cross-contamination risk. This preference is based on the mechanical action of the towel and the reduced risk of aerosolizing pathogens into the environment. The decision often comes down to balancing environmental considerations with the need for the highest standard of hygiene.