Biology: February 2010 Archives


February 14, 2010

OK, so I thought that the Dyson Blade dryer was scary, but check this out: gas plasma-based hand sanitizers.
Plasmas engineered to zap microorganisms aren't new. During the last decade, they have come into use to sterilize some medical instruments. But using them on human tissue is another matter, said Mark Kushner, director of the Michigan Institute for Plasma Science and Engineering and a professor at the University of Michigan in Ann Arbor. "Many thousands of volts drive the generation of plasma," he said, "and normally one doesn't want to touch thousands of volts." But the design of the new hand sanitizers, he said, protects people from doing so. Reassured by that design, about five years ago he put his naked thumb into a jet of microbe-destroying plasma at the lab of another plasma researcher.


The plasma cleaners make their antibacterial cocktails by running electrical current through air, said David B. Graves, a professor of chemical engineering at the University of California, Berkeley, who has worked on low-temperature plasma applications for 25 years.

Professor Graves is doing computer simulations of the chemical reactions that occur in the Morfill plasmas. The electric current ionizes the oxygen, nitrogen and water vapor in the air, he said, eventually creating the nitric oxide, hydrogen peroxide and particles that are so effective against bacteria, viruses and fungi.

OK, so I'm sold that it probably won't burn my hand off, but that doesn't necessarily mean that it's something I want to expose my hands to. Nitric oxide, for instance, is not very good for you:

Nitric oxide vapors are a strong irritant to the pulmonary tract. At high concentrations initial symptoms of inhalation may be moderate and include irritation to the throat, tightness of the chest, headache, nausea and gradual loss of strength. Severe symptoms may be delayed (possible for several hours) and include cyanosis, increased difficulty in breathing, irregular respiration, lassitude and possible eventual death due to pulmonary edema in untreated cases.

That sure sounds like fun!

Seriously, the relevant question here is how wide the difference is between the level at which the relevant chemicals deactivate bacteria, viruses, etc. and the level at which they cause side effects in humans. If there's a wide gap, then great, but if not, then we have to worrry about how well the plasma generator is calibrated. In addition, there's the question of the effect of regular exposure (e.g., for health care workers). I'll be interested to see what safety studies show.