If a medium-sized asteroid were to hit in Earth's oceans a tsunami wouldn't be the only worry, U.S. scientists say -- the ozone layer could be at risk too.

A computer simulation by researchers at the Planetary Science Institute in Tucson suggests water vapor and sea salt thrown into the atmosphere could damage the protective layer and create record levels of ultraviolet radiation that could threaten life on the planet, NewScientist.com reported Wednesday.

Elisabetta Pierazzo and her colleagues used global climate models to study the effect of an asteroid collision happening at sea. They focused on medium-sized asteroids, about a half-mile wide.

To date, 818 asteroids that are at least that wide have been found orbiting in paths that could bring them close to Earth.

The computer simulations showed such an asteroid would throw 46 billion tons of water and vapor across an area more than 600 miles wide and as much as, or more than, 100 miles above Earth's surface.

Once in the atmosphere, the water and compounds containing chlorine and bromine from vaporized sea salts could destroy ozone above the atmosphere at a much faster rate than it is naturally created, the researchers say.

"It will produce an ozone hole that will engulf the entire Earth," Pierazzo says.

The resulting ultraviolet-radiation levels would be higher than anywhere on Earth today, the researchers say.