A warning earlier this week from the Environmental Protection Agency that Americans should test the radon gas level in their homes coincides with a University of Utah professor's belief that there needs to be a better understanding about radioactivity levels and sources.

Even though the atomic age is as old as the computer age, nuclear terms like "millirem" and "picocurie" remain a mystery to schoolchildren who talk knowledgeably about interfaces and floppy discs.And the mystique surrounding anything "nuclear" can be both dangerous and frightening.

Considering all of the sources of radiation, about 80 percent of the day-to-day background radiation seeps naturally from the earth in the form of radon gas, said Dr. Gary M. Sandquist, director of the U.'s nuclear engineering program.

It is the naturally occurring radon that is believed to pose an increased cancer risk for at least 3 million households nationwide, according to the EPA health advisory released Monday.

Perhaps radiation would be easier to understand if layman's terms were developed to make the radiation measurements easier to relate to.

Sandquist said Eastern nuclear physics students created a tongue-in-cheek measure called the "Rather," named after network television news anchor Dan Rather. The students compared radiation exposure from the Three Mile Island nuclear generating plant accident in 1979 to watching one half-hour news broadcast about the accident, since one-half hour of Dan Rather exposed viewers to as much radiation from the television as did Three Mile Island, Sandquist said.

Although the radiation levels are much lower from television, there were five to 10 times as many people watching the television as there were people who could possibly have been exposed to radiation from Three Mile Island.

Following the same layman's path, radioactivity levels could just as easily be called a Vanna or Ernie after a television game show or Sesame Street program.

Ironically, radiation testing in the Pennsylvania area near Three Mile Island after the nuclear plant accident showed natural radon gas seeps caused higher levels of radioactivity than the nuclear accident did, Sandquist said.

Another roadblock to the public's understanding of radiation is the distrust of information provided by the government, or companies like GPU Nuclear Corp., owner of the Three Mile Island plant.

GPU recognized it had a public relations and credibility problem after the accident so it set up independent monitoring stations around Pennsylvania to make reports of radioactivity levels more credible.

The Department of Energy then picked up on the idea to overcome publicity problems at the Nevada Test Site by starting a community radiation monitoring program of its own, Sandquist said.

Since 1981, five independent monitoring stations in Utah and 13 more in Nevada and Southern California have been established and are being operated by independent monitors - many of them high school science teachers who can use the monitoring equipment to help teach their students basic principles of nuclear physics.

The University of Utah provides the training for the community monitors, and Sand-quist is in charge of the monitoring station situated outside the Merrill Engineering Building at the U.

All of the stations are situated in public places where community residents can observe some of the more visible instrument readings, Sandquist said. The Salt Lake station is also fitted with a satellite link that transmits data to DOE.

The specialized detection equipment in Salt Lake City and at the 17 other stations hums constantly as it sniffs out radioactive isotopes. DOE tells the monitors of announced tests so additional equipment can be put in operation to detect any radioactive noble gasses if they drifted from the test site.

To illustrate the equipment's sensitivity, Sandquist said radon gas levels in culinary water are typically higher in the fall because more of the water comes from underground aquifers that trap the gas. Because of that, Sandquist said he could tell whether home-canned fruits or vegetables were prepared in the spring or fall by measuring the amount of radon gas trapped inside the bottle.

But don't expect radon gas levels to influence judges at the state fair as they examine bottles of peaches - the radioactivity levels are too small to be of interest, Sandquist said.

While the monitoring station at the U. effectively measures the day-to-day radiation levels in the community, it has yet to detect anything straying into the Salt Lake Valley from an underground test at the Nevada site. Stray radiation from man-made nuclear reactions is easy to detect because it contains isotopes like cobalt 60 that is not produced by nature.

The Salt Lake monitoring station was not in place at the time of the Three Mile Island accident but did detect fallout after the Soviet nuclear reactor meltdown at Chernobyl in 1986. The change in the radioactivity level was only 1 percent, but the cause was obvious because the isotopes detected were man-made.

Improved measurement techniques led the EPA to drastically change their evaluation of background radiation levels in the U.S. Typical background radiation levels nationwide used to be calculated at about 80 millirems per year. Such background levels are now known to be much higher - around 360 millirems.