Sir James Dyson, the inventor, has threatened legal action over a scientific study that claims his jet-air hand dryer spreads bacteria.

The research paper, by academics at the University of Westminster, claims that the Airblade device, which removes water from hands with a 400mph blast of hot air, can disperse microbes over a distance of up to two metres.

The scientists used yeast particles to test dispersal by the Airblade and conventional warm-air hand dryers in public washrooms. Petri dishes containing agar, a substance in which bacteria can take hold, were placed at 25cm intervals to catch the particles and incubated to reveal any bacteria growth.

“The [Airblade] dispersed artificial contamination further than the warm-air hand dryer or paper towels, and bacteria, including potential pathogens, were detected on the inner surfaces and in the air flows of Airblade dryers in public washrooms,” the study concludes.

However, Dyson, one of Britain’s wealthiest men with an estimated fortune of £760m, has forced the university to remove mention of his product from subsequent versions of the study. His firm’s lawyers are assessing the merits of a legal challenge.

Dyson’s company claims the study, funded by the European Tissue Symposium, a trade body representing manufacturers including Kimberly-Clark, and presented at the Tissue World conference in Nice earlier this year, is “flawed and questionable”.

Last week Keith Redway, a medical microbiologist in the university’s biosciences department and co-author of the study, insisted the research was “impartial and robust” and open to scrutiny.

“[Dyson's] response doesn’t surprise me. The fact our research was funded by the tissue industry did not affect the results; it does not mean the findings are biased. The university is independent,” he said.

“Dyson may not like our results but we can’t change them to suit [him]. We can provide all the methodology; we have nothing to hide. They are defending their corner but they have sold these dryers as very hygienic and I cannot agree. Paper towels allow frictional removal of some bacteria such as MRSA, which electric hand dryers simply cannot achieve.”

Advice issued by the World Health Organisation to prevent the spread of swine flu recommends the use of paper towels.

Dyson Ltd said the Airblade uses up to 80% less energy than warm-air hand dryers and, unlike paper towels, does not contribute to landfill. According to the firm, the device uses an antimicrobial coating on its surface to prevent bacterial transmission from user to user and a filtration system to remove 99.9% of bacteria from the hot air used to dry hands.

“This paper towel industry-funded research is flawed and Dyson has challenged the University of Westminster’s questionable methodology and results,” the company said.

“The Dyson Airblade hand dryer is hygienic and is endorsed by the Royal Society of Public Health.”

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