Hand dryers are electric devices found in a public washroom and are used to dry hands. They may either operate with a button, or more recently, automatically using an infrared sensor.
Costs
Hand dryers have been popular with industries for their apparent economies. According to manufacturers hand dryers can cut costs by as much as 90%, when compared to paper towels. They require very little maintenance compared to paper towels, which must be replaced, and the paper waste removed.
Environment
Due to the reduction in litter and waste in comparison with paper towels, which cannot be recycled, hand dryers are also claimed to be better for the environment. One source claims that an average fast-food restaurant using paper towels, annually, results in 9 fully-grown trees being cut down, and 1,000 pounds (≈450 kilograms) of landfill waste created, though many are often unaware of these consequences. Even before the paper towels are used, each ton has claimed 20,000 gallons (≈76000 litres) of water in chemical cleansing. 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. The flip side of these arguments is that: a) the very reason that paper towel is not recyclable (i.e. that the fibre is too weak) also makes it easily broken down as opposed to the bi-products created by producing electricity, b) it is possible to use trees from plantations that are grown specifically for that purpose instead or ripping up old-growth forests as is implied and c) it is also possible to use recycled or desalinated water in the manufacturing process. In addition, paper towel may not be recyclable but it can be made from recycled paper.
It's 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.
See also Tissue paper for information about the ways in which the paper towel industry has worked to improve its sustainability.
Hygiene
Whether hand dryers are more or less hygienic than the alternatives is a matter of dispute.
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".
In 2008, a study was conducted by the University of Westminster, London, to compare the levels of hygiene offered by paper towels, warm air hand dryers and the more modern jet-air hand dryers . The key findings were:
- 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%
- 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:
- the jet air dryer, which blows air out of the unit at claimed speeds of 400 mph (≈640 km/h), was capable of blowing micro-organisms from the hands and the unit and potentially contaminating other washroom users and the washroom environment up to 2 metres away
- use of a warm air hand dryer spread micro-organisms up to 0.25 metres from the dryer
- paper towels showed no significant spread of micro-organisms.
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 method | Effect on Bacterial Count |
|---|---|
| Paper towels and roll | Decrease of 24% |
| Hot-air drier | Increase of 117% |
Another paper found that air dryers dispersed marker bacteria in a radius of three feet (one metre) 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 agreed upon by another study, which also found that the mechanical action of paper towel drying removed bacteria, which is something hand dryers cannot do.
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.
Besides their shortfalls in terms of hygiene standards, hand dryers can also be costly to purchase and install. This means those responsible for facility management must do a careful cost analysis to determine whether they are cost effective in their building.
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 (68% vs 14%). On the whole they also considered paper towels to be the most hygienic form of hand drying in public washrooms (53% vs 44%).
