Umatilla Chemical Depot, Hermiston, Ore. -- An analysis is under way to determine if a Umatilla Chemical Agent Disposal Facility worker\'s skin blister was caused by contact with mustard agent. The facility is currently processing mustard agent ton containers in preparation for the Agent Trial Burns. On Wednesday, March 17, two maintenance employees, wearing the appropriate protective clothing for the area consisting of masks, gloves, boots, aprons and cotton coveralls, were working on equipment calibration in the facility's Munitions Demilitarization Building. At about 1 p.m, as the employees were exiting the working area, an agent monitor registered with low-level mustard readings in the airlock. Following standard procedures, the workers' protective equipment and clothing were removed and the individuals were decontaminated. Medical evaluation at the facility's clinic identified a red spot on the skin of one employee, which progressed over the following 24 hours to a blister. "Safety of our employees is our No. 1 priority," said Mike Strong, the Army Site Project Manager at the Umatilla Chemical Agent Disposal Facility. "We will fully evaluate and assess the events that led to this incident as we provide appropriate care for the employee." At no time was there danger to the public or the environment, Strong said. At this time it has not been determined whether the skin blister may be a symptom of potential mustard agent exposure or has another cause. As part of a medical analysis to determine cause, the worker's blood has been drawn and is being prepared to be sent to an independent lab for testing. The employee has returned to work, with no other adverse effects. An analysis is under way to determine the root cause of the event. As a precaution, all entries into the chemical processing areas have been upgraded to the highest levels of protective clothing pending further review.