Hand dryer


Hand dryer is an electric machine which makes use of heating element and an air blower to dry the hands. It is commonly used in the public bathrooms as a cost-effective alternative to paper towels.
It may either operate with the push of a button or automatically using a sensor.

History

The earliest hand dryer was patented in 1921 by R.B. Hibbard, D. J. Watrous and J.G. Bassett for the Airdry Corporation of Groton New York. This machine was sold as a built in model or freestanding floor unit that consisted of an inverted blower that was controlled by a floor pedal. Known as "Airdry The Electric Towel", these units were used in restrooms, barbershops and factories. Airdry Corporation moved to Chicago and San Francisco in 1924 to centralize their distribution.
The hand dryer was later popularized in 1948 by George Clemens, who founded World Dryer and invented the Model A, World Dryer’s flagship model. In 1993, Mitsubishi Electric introduced a new type of hand dryer "Jet Towel" that blows jets of air on both sides of the hand, pushing the water off rather than evaporating it.

Costs

Hand dryers have been popular with industries for their apparent economies. According to manufacturers, hand dryers can cut costs by as much as 99.5%. They require very little maintenance compared to paper towels, which must be replaced. An added benefit is the removal of the paper waste. Hand dryers represent a larger initial investment, so those responsible for facility management must do a careful cost analysis to determine whether they are cost effective in their building. Costs are always relative to the kWh cost that the facility is charged by its provider. In the UK, this will typically be around 10-12p, the only way to compare costs accurately is to work out the rated energy consumption and divide it by the number of drys the hand dryer is capable of performing back to back in 1 hour, this will give the energy consumption per dry. The world's lowest energy hand dryer uses just 1 watt-hour per dry and is rated at 0.24 kW.

Effect on environment

Due to the reduction in litter and waste in comparison with paper towels, which cannot be recycled, hand dryers are claimed to be better for the environment. Another study shows that whereas the majority of the environmental impact of a hand dryer occurs during its use, the environmental impact of paper towels is predominantly in the material production and manufacturing stages. It is estimated that hand dryers use 5% less energy than paper towels in the first year, and 20% less over five years. A World Dryer study of 102 hand dryers installed in public schools in Topeka, Kansas, claimed an annual savings of 34.5 tons of solid waste, 690,000 gallons of water, and 587 trees; another World Dryer study of 153 hand dryers in the Iowa state capitol showed an annual savings of 10.5 tons of solid waste and 176 trees. However, a Dutch study published in March 1995 indicated that there was environmental parity between hand dryers and paper towels as hand drying methods when all factors were taken into consideration.

Hygiene

In 2009 a published study was conducted by the University of Westminster to compare the levels of hygiene offered by paper towels, warm air hand dryers and the more modern jet-air hand dryers. It found that after washing and drying hands with the warm air dryer, the total number of bacteria was found to increase on average on the finger pads by 194% and on the palms by 254%; drying with the jet air dryer resulted in an increase on average of the total number of bacteria on the finger pads by 42% and on the palms by 15%; and after washing and drying hands with a paper towel, the total number of bacteria was reduced on average on the finger pads by up to 76% and on the palms by up to 77%.
The scientists also carried out tests to establish whether there was the potential for cross contamination of other washroom users and the washroom environment as a result of each type of drying method. They found that:
In 2005, in a study conducted by TÜV Produkt und Umwelt, different hand drying methods were evaluated. The following changes in the bacterial count after drying the hands were observed:
Drying methodEffect on Bacterial Count
Paper towels and rollDecrease of 24%
Hot-air dryerIncrease of 117%

Another paper found that air dryers dispersed marker bacteria in a radius of three feet and onto the investigator's laboratory coat. Another study found that hot air dryers had the capacity to increase the bacterial count on the skin, and that paper towel drying decreased skin bacterial count. This is corroborated by another study which found that the mechanical action of paper towel drying removed bacteria, something air dryers cannot do.
Doctors at the University of Ottawa claim that "the blowing of warm air may lead to an accelerated dehydration of the skin surface, thereby affecting the viability" of the microorganisms, and that the warm air may "penetrate all the crevices in the skin, whereas absorbent towels may not reach such areas, even though the skin appears dryer".
The European Tissue Symposium, a trade body, has produced a position statement on the hygiene standards of different hand drying systems. This summarises some of the scientific research undertaken.
Dyson have countered the claims presented, suggesting that the results were intentionally falsified.

Noise

Many people object to the loud noise that hand dryers make. Typically, installed hand dryers make over 80 decibels of sound at a distance of while in operation. It is much louder for the user and may exceed safety limits for children whose ears are at the height of the device. Some units, however, are designed to be quieter at the cost of drying speed.

Reception

Research conducted in 2008 indicated that European consumers much prefer hand towels over hand dryers in public washrooms. 63% of respondents said paper towels were their preferred drying method, while just 28% preferred a hand dryer. Respondents overwhelmingly considered paper towels to offer faster hand drying than electric hand dryers. On the whole they also considered paper towels to be the most hygienic form of hand drying in public washrooms.