For the third time since last week, employees at an Aberdeen Proving Ground research lab were evacuated and medically evaluated because of possible exposure to a dangerous chemical.
Four employees were conducting routine experiments with phosgene at about 8 a.m. Thursday at the Edgewood Chemical Biological Center, when one detected the chemical?s odor, APG officials said.
At low concentrations, phosgene has a “a pleasant odor of newly mown hay or green corn, but its odor may not be noticed by all people exposed,” according to the Centers for Disease Control and Prevention. “At high concentrations, the odor may be strong and unpleasant.”
Although it can be converted to a liquid form, phosgene is a poisonous gas at room temperature.
It was widely used during World War I as a choking agent and was responsible for the majority of deaths due to chemical warfare, the CDC said.
A cylinder of phosgene was being moved when the employee noticed the odor and called 911. Operations were stopped, APG officials said. They said emergency personnel discovered a valve on the cylinder wasn?t completely closed and closed it.
Laboratory filters and an environmental containment system would have prevented the gas from leaking out, officials said.
They said no presence of phosgene was detected in the room, and none was released into the environment.
None of the employees showed any symptoms of exposure, but they were taken to Upper Chesapeake Medical Center as part of the emergency protocol, an APG spokeswoman said.
APG spokeswoman Pat McClung said last week?s incidents remain under investigation, and there was no connection between them and the recent episode. The earlier incidents appeared to involve electrical problems.
