Mobile decontamination units-room for improvement?

Mobile decontamination units are intended to be used at the accident site to decontaminate persons contaminated by toxic substances. A test program was carried out to evaluate the efficacy of mobile decontamination units.

The tests included functionality, methodology, inside environment, effects of wind direction, and decontamination efficacy.

Three different types of units were tested during summer and winter conditions. Up to 15 test-persons per trial were contaminated with the imitation substances Purasolve ethyl lactate (PEL) and methyl salicylate (MES). Decontamination was carried out according to standardized procedures. During the decontamination trials, the concentrations of the substances inside the units were measured. After decontamination, substances evaporating from test-persons and blankets as well as remaining amounts in the units were measured.

The air concentrations of PEL and MES inside the units during decontamination in some cases exceeded short-term exposure limits for most toxic industrial chemicals. This was a problem, especially during harmful wind conditions, i.e., wind blowing in the same direction as persons moving through the decontamination units. Although decontamination removed a greater part of the substances from the skin, the concentrations evaporating from some test-persons occasionally were high and potentially harmful if the substances had been toxic. The study also showed that blankets placed in the units absorbed chemicals and that the units still were contaminated five hours after the end of operations.

After decontamination, the imitation substances still were present and evaporating from the contaminated persons, blankets, and units. These results indicate a need for improvements in technical solutions, procedures, and training.