Research in air filtration and house-hold cleanliness had already led Dyson to build an in-house testing laboratory overseen by microbiologist Toby Saville. “There wasn’t an established set of standards for hand dryness, so we had to deduce them,” Churchill says. Three questions directed the team’s inquiries:
(1) How dry is dry? Churchill says of the first test: “We had people dry their hands to their own standard with paper towels. We found dryness to be when there is 0.1 gram of water left on your hands.”
(2) Is drying necessary? Saville found the answer to be a definitive yes: Volunteers briefly handled a raw chicken, washed their hands using a medical protocol, and dried them to various degrees. The data showed that damp hands carry up to 1,000 times more bacteria than dry ones.
(3) Will people really dry their hands? The team set up video cameras in public restrooms to observe hand-dryer use. Barring the remarkable portion of people who skip hand washing altogether, those who dry do so in a hurry. Most of the people observed held their hands under a hot-air blower for about ten seconds, gave up, and finished the job using their clothes.