They hope it will never happen, but they want to be ready if it does.

Utah Valley Regional Medical Center, Provo, and University Hospital, Salt Lake City, are planning mock disaster drills. On July 25, after a simulated mustard gas leak at Tooele Army Depot, each hospital will accept and treat a "patient" claiming to be contaminated by mustard gas."Over 60 percent of the nation's chemical warfare agents are stored at Tooele Army Depot," said Dr. Clark Searle, chief of Dugway Proving Ground's clinical support section. "We are involved in a program to dispose of them, but while they are there, the potential exists for civilians and Army personnel to be exposed to an accident.

"We are somewhat prepared for a mass casualty, but are not equipped for a long-term medical follow-up. That is where you come in," Capt. Searle told Utah Valley's medical team at a recent preparatory meeting.

Bob Pagnani, ambulance supervisor at Dugway's health clinic, said that although a variety of chemicals are stored in Utah, officials are most concerned about training hospital workers to deal with cases of mustard gas exposure.

"All of the other agents we have at Dugway work fast. People either live, or they are dead quickly. With mustard gas patients, the symptoms may take hours to show up, and unless precautions are taken, the patient will contaminate everyone he comes in contact with.

"The amount of mustard gas (in solid or liquid form) that would fit on the head of a nail is enough to kill," he said.

Mustard gas - a blistering agent that causes serious burns within two hours after contact with flesh - was used in World War I and was stockpiled by the United States for many years.

Part of Tooele Army Depot is used as a storage facility, holding most of nation's chemical weapons stockpile. Its south annex in Rush Valley holds a facility that tests methods for destroying aging chemical weapons.

Dugway is the central testing point for the Defense Department's chemical and biological defenses, and the main test site for battlefield smokes and obscurants. The base was founded in 1942, and records from the earlier periods are incomplete, so base officials are unsure of what chemicals are buried in what locations. The military has been paying private contractors to locate chemicals that may pose a health risk to the government workers.

"Mustard gas is still being used in Iran, Iraq and Afghanistan," Searle said. "It is pretty well documented.

"Mustard gas can be colorless and odorless, and an exposed person might not show any symptoms for a few hours. When it bonds to cells, it causes cell death."

Searle said the gas causes burns to skin, eyes and lungs. Liquid from blisters can contain active agents that can burn medical personnel.

"In one case where five Afghan patients were flown to a New York hospital for treatment, 150 medical workers were contaminated by mustard gas because they didn't know how to protect themselves," Pagnani said. "They got blisters on their fingers and couldn't work for a while."

On Monday, "gas victims" in plastic suits will be transported to the two hospitals. Medical personnel in similar suits will greet them and take them to isolated treatment rooms. Crews will look for ways to limit contamination to the rest of the hospital, dispose of used supplies without causing more damage, and treat the patients. They will also spend hours "decontaminating" the emergency area.

"If there were any kind of accident, the top medical specialists in the world would be flown to Utah within 24 hours," Searle said. "We just want to give these two hospitals some training on what they could expect in the first 24, and how to minimize the danger to everyone involved."