Personal decontamination after exposure to stimulated liquid phase contaminants: functional assessment of a new unit

To evaluate the efficacy of a decontamination station following exposure of volunteers to liquids with physical characteristics comparable to sarin and mustard gas.

Twenty-four volunteers participated in the experiment which was performed with all staff wearing personal protective equipment including respiratory protection. The clothes, skin, and hair of the volunteers were contaminated with the simulated liquid phase contaminants, ethyl lactate and methyl salicylate. Sulphur hexafluoride gas was used to confirm the ventilation efficacy. Decontamination followed guidelines using a two-stage procedure. In the first chamber, all volunteers received a 3-minute shower with water at 30 degrees C, and their clothes but not their respiratory masks were removed. In the second, they were twice washed thoroughly with soap and water. After decontamination, the volunteers entered a third chamber for first aid measures.

The air concentration of sulphur hexafluoride was reduced by 1:10,000 between the first and the third chambers. Ethyl lactate and methyl salicylate were measured in low concentrations in the third chamber. The capacity was 16 volunteers per hour with two-thirds on stretchers. After self-decontamination of the staff, the concentration of ethyl lactate increased significantly in the third chamber, consistent with residual ethyl lactate adsorbed by their underwear. This observation revealed a deficiency in the guidelines for self-decontamination.

The capacity of the decontamination unit was found to be 16 volunteers per hour. The ventilation system and guidelines of the decontamination unit were demonstrated to be effective under the conditions examined. The self-decontamination of the staff was not optimal.