While the lab remains the home of most scientific experiments, James G. Anderson's most important experiments take place more than 30 miles in the air.

Anderson's business is flying balloons--most more than 100 times the size of the Good year Blimp--an activity which has won him a reputation as one of the world's top experts in atmospheric chemistry. And in doing so, he has found himself at the heart of one of today's most pressing environmental questions.

In recent years, scientists, government officials and the public have become increasingly concerned that man-made and natural chemicals are destroying the ozone layer, the portion of the atmosphere that protects the earth from the sun's deadly ultraviolet radiation.

As a result, Anderson's expertise is in high demand, and he has answered the call with a series of innovative experiments. In the process, he has become the first person ever to successfully examine the stratosphere, a region too high for airplanes and too low for satellites to explore.

Anderson, a native of Spokane, says he has always had a fascination for balloons, but in the wheatlands of eastern Washington balloon flying was hardly the rage. He studied economics and then political science, but the science bug bit him, and before long he was off to pursue a career in atmospheric chemistry.

Only after graduating from the University of Washington at Seattle did he conduct his first high altitude experiments. While working on his doctorate in physics at the University of of Colorado, he began experimenting with sending rockets into the atmosphere. His balloons didn't enter the picture until he became an assistant professor at the University of Pittsburg, and by the time he landed at Harvard, he was a seasoned veteran.

In his efforts to learn the chemical compositions of the stratosphere. Anderson has become the the first person ever to actually conduct experiments in the mysterious region. After constructing highly sensitive equipment at his Oxford St. lab, he and his crew travel down the National Scienific Balloon Facility in the heart of the cowfields of Palestine, Texas. There they carefully assemble and load up unmanned balloons--which when inflated reach the the same height as Boston's John Hancock tower--with equipment that will measure the gas composition of the stratosphere.

Ozone, a highly unstable union of three oxygen atoms, provides the vital function of absorbing most of the sun's ultraviolet radiation. It is continuously being formed in the stratosphere, when regular oxygen molecules interact with ultraviolet radiation.

Life without ozone could not exist, as large amounts of low-energy ultraviolet radiation would pass freely to the ground. Such radiation could damage plants, reduce crop yields, promote skin cancer, and induce cataract-related blindness in all land animals.

Nature has provided just the right level of ozone for life; if one could squish all of the stuff in the stratosphere, it would amount to a strip of gas about an eighth of an inch thick. The danger is that various man-made gasses may be seeping up into the stratosphere and destroying this delicate balance, causing ozone to be eaten up faster than it is being made.

Scientists believe that fluorocarbons used in aerosol propellants, refrigeration fluids, fillers for synthetic foams, and electronic parts cleaners are capable of doing the most damage. In addition, gasses produced by burning coals or using artificial fertilizer are also thought to be dangerous.

These substances float up into the stratosphere, where they are broken up into molecules of fluoride and chlorine. And chlorine, which is known as a "free radical," is very bad for ozone; when the substances mix, ozone is broken down.

The stuff does not have to be entirely destroyed to be threatening. Anderson says if the amount of atmospheric ozone drops by as little as 10 percent, enough ultra-violet radiation could probably seep through to be "extremely serious," and if it dropped by 50 percent, it would prove devastating.

While scientists know that man's activity is destroying the ozone layer, there is little consensus over the extent of the damage, and over whether drastic steps are in order.

"Potentially, there is a very big problem, but concern is still premature," says George M. Whitesides, professor of chemistry. "The basic scientific knowledge is not there yet."