His eyes teared, his nose ran and his lungs burned. But Spec. 4 Eric Hackman could do little but endure the discomfort caused by tear gas wafting through an Army gas chamber.

Hackman, 24, of Latrobe, Pa., and other Fort Eustis soldiers got a good whiff of the gas as part of their training in the use of masks and clothing designed to protect them from chemical weapons.The soldiers had been through the training before. They knew how to suit up and clear their masks by breathing out hard. But events in the Persian Gulf were making the refresher course particularly timely.

"In the event he goes to Saudi Arabia and if he doesn't do the procedure properly, does not clean the mask properly, he could be exposed to the chemical, get sick - die," said Maj. Frank Connor, chief of the Training Division at Fort Eustis.

About 230,000 U.S. troops have been sent to the Persian Gulf since Iraqi President Saddam Hussein sent his army into neighboring Kuwait on Aug. 2. Saddam has stockpiles of chemical weapons and has used them against the Kurds in eastern Iraq.

U.S. soldiers train regularly in putting on their protective gear and performing their jobs. "If you are a truck driver, you have to be able to do your truck driving in an NBC environment," said Sgt. 1st Class Larry Price, head of the post's "NBC" - nuclear, biological, chemical - branch.

Hackman and others volunteered to remove their masks inside the chamber, a tent set up in a forest clearing. Some commanders require it as part of the training. Others do not.

The exercise is intended "so you will be confident (in the mask) when you go into the battlefield," said Staff Sgt. Marvin Ward.

The smell of the gas seeped from the tent and the wind blew it on those waiting their turn.

"Let's get it over with," one soldier said.

About 10 masked soldiers filed into the chamber. When they left 10 minutes later with their masks off, they were bent over, coughing and waving their hands.

"Don't touch your face," cautioned Sgt. Donna Niemuth, in charge of the chamber. "Look into the wind."

Hackman's eyes were redder than most.

"You want to rub your eyes," said Hackman, of the 155th Transportation Company based at Fort Eustis. "Right before I got out the door, I got a good breath."

Spec. 4 Richard Hill, also of the 155th, wasn't as bothered by a runny nose.

"I blew it good before I went in there," Hill said. "It burns. I want to scratch my eyes. There's a real nasty taste in my mouth."

The tear gas wore off in about 15 minutes.

The soldiers also spend time in the classroom, learning about chemical agents much stronger than tear gas.

Price taught a recent class to members of the Army Reserve's 359th Transportation Battalion based in nearby Hampton.

Price told them there are four NBC tenets: avoidance, protection and decontamination, and pulling all three together to perform in a contaminated environment.

Chemical warfare agents include nerve gas, blister agents like mustard agent, and blood agents that strip oxygen from the blood. They can be fatal or incapacitating, Price said. The effects of some agents wear off quickly; others can last many years.

Nerve agents cause loss of muscle control and affect nerve endings, Price said.

"How many of you took Black Flag and sprayed it on a bug?" he asked. "That's what nerve agent does to you."