| W | Warm water: the shower water temperature should be at least 35°C (but lower than 40°C) to ensure optimal removal of contaminants. |
| A | Aid: the removal of a chemical contaminant (particularly powders) can be increased by 20% by the use of a washing aid such as a cotton face cloth or sponge during showering. Washing aids should be safely disposed of after single use. Do not reuse washing aids. |
| S | Soap: the use of detergent at a concentration of 0.1%–0.5% (v/v) has been shown to assist decontamination of lipophilic (oily) substances. Most UK mass decontamination units (MDUs) have the capacity to add liquid detergent to the shower water via a metered dosing system. |
| H | Head to toe: casualties should be instructed to start by washing their head and to work their way down to their feet. Casualties should tilt their head backwards when washing their hair to avoid spreading contamination to the face. |
| E | Expedited: in order to avoid the ‘wash-in’ effect (which may enhance the dermal absorption of certain chemicals), the shower needs to be performed within 90 s. Ideally, 1 min with soapy water and the remaining half minute using water only (rinse). The 90 s timing reflects the optimal shower duration. Longer durations should be avoided. |
| D | Drying with a towel is the critical step for removing many chemical contaminants! Following use, towels must be considered to be heavily contaminated and should be disposed of according to local regulations. |