Ozone can clean fruits and vegetables. .

Ozone, the gas that protects the Earth from ultraviolet radiation, may soon give U.S. food shoppers better protection from harmful bacteria. Retailers could sanitize fruits and vegetables by exposing them to ozone before they go on sale, suggests Gary Rodrick, a professor with the University of Florida's Institute of Food and Agricultural Sciences, Gainesville. In Europe, ozone has been used for decades to sanitize water and food products.

"With a 99.9% kill rate, it's far more effective than current sanitizing methods, such as commercial fruit and vegetable washes," he argues. "The Food and Drug Administration recently gave the go-ahead to use it commercially in U.S. supermarkets and food-processing facilities. It also will be more acceptable than food irradiation, which has raised fears among some consumers."

Moreover, ozone used in food sanitation will not contribute to air pollution or smog. "In the upper atmosphere, ozone shields the Earth from ultraviolet radiation. In some urban areas, ozone forms at ground level when certain airborne chemicals interact with the sun's light and heat, contributing to smog. However, the sanitation process uses very low levels of ozone, and the entire process must be precisely controlled to be effective."

Ozone molecules contain three oxygen atoms and are formed when ordinary oxygen molecules containing two atoms are forced to take on a third. Rodrick says that ozone's usefulness as a sanitizing agent comes from its unstable molecular structure--the third oxygen atom tends to break apart from the ozone molecule, releasing energy. "When you expose an apple to ozone, bacteria on the fruit's surface will begin absorbing ozone molecules immediately. Those molecules break apart within seconds, and when they do the bacteria literally...