Electric Air Dryers

 Picture


What is the appeal of hot air dryers? The answer to that question is not so easy, as more and more evidence is confirmed showing the low efficiency and disastrous hygiene effects this form of hand drying gives. The electric hand dryer seems, on first consideration an "easy" answer, when the need for a hand drying system is recognised. Pay once, fit it to a wall and forget it ! Sounds great. The problem is , the users don't like them, they often prove unreliable (how many times have you walked up to an inoperative airtowel?), they are prone to vandalism, they are slow to dry the hands, and the hygiene factors associated with them are horrific.
Think for a moment on how an airtowel works. The user first washes his/her hands in warm water. the hands are then placed under a blast of warm air to be dried. Where does this air come from? The machine sucks up cool air from the washroom, laden with the dust mites, bacteria and the faecal dust prevalent in toilet areas. This air is then heated up and blasted onto the warm moist hands - a perfect moist, warm surface for these bacteria to adhere to.
To compound the problem, the high volume air dryers blast some of the now bacteria laden fluid drops from the hands, into the surrounding area, including onto the arms and clothes of the user.
One last effect from the dryer use is that in drying the hands, the skin on the hands is warmed up, and when exposed to the cooler air outside the washroom a vast majority of users feel a need to wipe their hands on their clothes, as the cooler air gives the impression that the hands are still wet.

How can air dryer manufacturers claim their machines are the most hygienic to use? Their claims are based on laboratory research studies commissioned by the airtowel manufactures, and are not performed in typical dust and bacteria laden restroom environments. The studies don’t reflect the way people typically wash and dry their hands. The test subjects washed their hands much longer than usual, had to totally dry their hands (usually for over a minute), and they use new air driers in pristine lab conditions.
The air towel researchers did not address the need for drying forearms and faces at all. When have you washed your hands properly (20 sec.), used a new (uncontaminated) air dryer, were able to use it in a laboratory (which has vastly cleaner air than in restrooms), and used it long enough to totally dry your hands?. Its not surprising then the results superficially appear favourable.

Lets examine the differing types of air dryers and their hygiene implications

First, warm air dryers (both press button and automatic types.)  To begin with they can deposit 150% – 500% more bacteria on your hands than you washed off!  They just re-circulate the bacterial laden air in the restroom. This contaminates the user’s hands, face, arms, clothing, wall and floor. They provide no mechanical or abrasive cleaning action. Most people do not use them long enough (40-50 seconds) to properly dry the hands. Damp hands increases bacteria growth, and transfer 1,000 times more bacteria than dry hands. Repeated use can cause chapping of the hands, which increases the potential of infection.

Air knife (blade) style air dryer units with a HEPA filter. The user places their hands in a narrow slot and the dryer uses high-speed air jets for drying. These have no mechanical or abrasive cleaning action. They filter incoming restroom air, but they spread bacteria, blown off typically improperly washed hands, which contaminates the restroom, the users clothing, and surrounding area. They can also contaminate the users hands from touching the sides of the narrow opening of the unit. They can not dry forearms or faces and may not work for deformed hands. They do dry hands faster than warm air driers. They can put 100% – 220% more bacteria on your hands than you washed off!  They also re-circulate the bacterial laden air in the restroom. This contaminates the user’s hands, face, arms, clothing, wall and floor. Most people do not use them long enough (20–30 seconds) to properly dry the hands. Damp hands increases bacteria growth and transfer 1,000 times more bacteria than dry hands.  As with other air dryers they can cause chapping of the hands, which increases the potential of infection.

Jet air dryers - air knife (blade) style (without HEPA filter). Dries hands faster than warm air driers. They work the same as the air blade driers but without a HEPA filter, and blast the warm, moist hands with bacteria laden warm air, and thus have the same hygiene problems as warm air dryers. The higher speed air flow will also increase the bacteria circulation, blowing more bacteria laden air on the user’s hands, clothing, and spreading bacteria in the restroom.

Another effect air towels have in busy washrooms is to increase the air temperature placing additional cooling load on air conditioning systems, raising energy consumption costs.