Frank Butrico, an off-site radiation monitor for the Atomic Energy Commission, was stationed in St. George on May 19, 1953, to check for radiation from the 32-kiloton nuclear blast, code-named Harry.

Today we know much more about Harry than Butrico did that morning. Dr. Joseph L. Lyon, the University of Utah researcher whose studies helped prove there is a link between fallout and southern Utah leukemia, recently said about 80 percent of the exposure in Washington County occurred on the day of and the week following the Harry shot.But as far as Frank Butrico was concerned early that morning, before the fallout arrived, Harry was just the ninth of 11 blasts fired off at the Nevada Test Site in the spring 1953 series of shots, called "Operation Upshot-Knothole."

Harry was detonated at the top of a 300-foot tower. It vaporized the tower and the fireball reached the ground, picking up large masses of earth and sand.

As the mushroom cloud swept away from the Nevada Test Site heading east, Harry dumped radiation on U.S. 93. Monitors detected it in a swath between 33 and 36 miles north of Glendale Junction, Nev. But of course the cloud continued to drift with the wind.

Butrico was not aware that Harry's fallout was approaching St. George until about 8:50 a.m., when his detectors began to show it was hitting the city.

Between 9:15 and 9:30 a.m. in downtown St. George, his instrument was off the dial, indicating exposure rates greater than 300 milliroentgens per hour.

Butrico double-checked his instrument and telephoned William Johnson, a radiation safety official at the Nevada Test Site, according to U.S. District Judge Bruce S. Jenkins' ruling in the 1982 fallout trial. Jenkins quoted extensively from Butrico's testimony.

After being told to "wait" after his first call, Butrico called Johnson again at 9:45 a.m. Johnson had no concrete plan other than to wash cars and try to get people indoors, according to Butrico. He told Butrico to get out the warning by radio or television.

The monitor then met with the mayor, who made arrangements with a Cedar City station for a radio announcement at 10:15 a.m.

"No other effort was made to reach towns to the east," Jenkins wrote. Butrico later estimated a level of 320 milliroentgens per hour could have hit St. George for about 20 minutes.

About noon, when he thought he could take a break, Butrico decided to go back to his motel to wash up. He used his instruments indoors to check the readings on his own body. For a short time the radiation levels in his hair were as high as they were outside. He showered several times that afternoon.

Asked whether Johnson told him that he should instruct others in St. George to decontaminate themselves, Butrico replied, "No. That subject was not brought up."

If Butrico is right about the level at the peak fallout from Harry and it lasted 20 minutes, anyone outside for that period would have been dosed with about 106 milliroentgens. This is equivalent to 95.4 millirems of tissue exposure.

A chest X-ray often delivers 10 to 50 millirems of exposure to a patient, depending on the equipment. Someone who stayed outside during those 20 minutes would have had the equivalent radiation exposure of between nearly two and nine chest X-rays.

But direct radiation may not have been nearly as hazardous as inhaling fallout particles that lodged in the lungs or drinking milk produced by cows grazing large areas contaminated with radioactive iodine.

A report by the Public Health Service, marked, "Published for the use of the Atomic Energy Commission and official health agencies ONLY," says Harry, "added measurably to the total external exposure for the test series. The area in which fallout occurred was inhabited by about 16,200 people."

Of course Harry's dose was in addition to the downwind residents' exposure from other shots. The 1953 series alone set off 252.2 kilotons of firepower - 19 times the force of the 13-kiloton bomb that devastated Hiroshima, Japan, eight years before. And that was only one year's tests.