HERMISTON -- Umatilla Chemical Depot officials are investigating whether two civilian guards were exposed to sarin nerve agent as they stopped in front of a storage igloo on Oct. 15.

As depot officials wait for more test results, state and county officials are asking why it took four days for them to be told about the incident. And audience members at a citizens advisory committee expressed outrage Thursday night.

Between 11 and 11:30 p.m. Oct. 15, the two male guards, who are civilians hired by the Army, were making sure the motors were running on the filter systems outside storage bunkers at the depot, which is about 35 miles south of the Tri-Cities. The guards' names were not released.

The bunker filters check for leaks of chemical agent within the storage igloos and prevent chemical agents from reaching the air.

Depot spokeswoman Mary Binder said the motors are checked every hour. "All they do is drive by, and in most instances just roll down the window and listen for the motor running," she said.

Monitoring earlier that day showed nothing unusual with the igloo that contains old munitions filled with GB sarin that have previously leaked, Binder said.

The guards noticed a metallic taste in their mouths and a sulfuric rotten egg smell, Binder said. One also had a runny nose. The guards don't wear masks during routine checks.

Of the three symptoms, only a runny nose is a potential symptom of sarin exposure, Binder said, noting that sarin is odorless.

The guards went to the depot clinic where their clothing was monitored and showed no sign of sarin. Blood samples also were taken, Binder said.

"There is no indication that it was agent and no idea at this point what it might be or might have been," she said.

However, Dennis Murphey, administrator for the state Department of Environmental Quality's Chemical Demilitarization Program, said he was told the blood tests gave conflicting information.

Results received Monday from the blood drawn Oct. 15 showed the guards had depressed levels of cholinesterase, CHE, which is one indication of exposure to nerve agent, said Depot Commander Lt. Col. David "Doc" Holliday. Exposure to pesticides also affects these levels.

The tests take about four hours to process but because the guards had said they did not think they were exposed and the physician agreed, the results weren't ready until Monday, Holliday said at the Oregon Citizens Advisory Commission Chemical Demilitarization meeting Thursday.

A second set of blood tests done Monday showed the CHE levels had returned to normal, Holliday said. The tests were done as a precaution, he said.

Urine samples also were sent to an Aberdeen, Md., laboratory, but it will be a few days before the results are back, Binder said.

The two guards immediately returned to work but have been restricted from areas where they might have to wear protective masks, she said.

Although the Holliday learned of the incident around midnight Saturday, other groups where not informed until Tuesday afternoon when Holliday determined the incident merited a report.

No news release was issued and some agencies, including Morrow and Umatilla counties' Chemical Stockpile Emergency Preparedness Programs and the Oregon Department of Environmental Quality, have questioned the four day delay.

"Our main concern is if anything happens (on the depot), we need to know about it as soon as possible," said Casey Beard, Morrow County emergency management director. "This time there was a considerable delay."

"We're at a stage right now in operations at the site that anything out of the ordinary is of interest to DEQ," Murphey said.

Morrow County Judge Terry Tallman questioned Holliday about the delay and said he would rather be notified and have it turn out to be nothing. "I would rather know than not know," he said.

The answers Tallman received did not bolster his confidence and led to more questions, he said. "I don't feel very confident about the reassurances of this organization."

Several other members of the commission and audience grilled the commander for about an hour and a half about the incident on Thursday.

Agency representatives discussed their concerns with depot officials during a regularly scheduled emergency responder meeting Wednesday in Hermiston.

Binder told the Herald there wasn't a delay in notifying any agency or the public because there never was an indication the guards had been exposed to a chemical agent, and depot officials were still investigating the incident.

The incinerator facility was not burning on Friday, Binder said.

Just last week, a federal judge in Portland ruled that the Army was not responsible for injuries suffered by 49 construction workers who believe they were exposed to a sarin leak at the depot in 1999.

The workers were inside a building when they reported feeling ill after apparently breathing noxious fumes. Symptoms included dizziness and metallic tastes.

But the source of the illness was never directly linked to a chemical agent leak.

The depot stores 220,604 munitions and containers filled with 7.4 million pounds of deadly nerve and mustard agents, which it began destroying Sept. 8.

Mustard agents stored at the depot date as far back as World War II.