Decontamination of materials / issued by the Ministry of Home Security (Air Raid Precautions Department).

Date:
1936
Catalogue details

Licence: Public Domain Mark

Credit: Decontamination of materials / issued by the Ministry of Home Security (Air Raid Precautions Department). Source: Wellcome Collection.

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    decontamination will be less. Once the gas has been thoroughly absorbed, no quick process of decontamina- tion will render such a surface safe for prolonged contact. As in nearly every other case, the efficiency of any treatment is largely dependent upon the speed with which it can be applied. Owing to their irregular surface the stone setts present a rather separate prob- lem if they occur in the centre of an important town. Preliminary hosing down with water would carry the blister gas into all the joints between the stones over a wide area. In such a situation it may be important to confine the contamination as much as possible, and so immediate treatment with a thin bleach cream will be necessary. This should be well brushed into all the joints between the setts and allowed to remain in contact with the surface for at least 15 minutes. ter this treatment, thorough hosing down of the whole area should be carried out and this will render the roadway quite safe for general traffic. In hot weather a smail amount of vapour may still be detected above the roadway, but it is not likely to be any source of danger. Pavements and concrete surfaces being smooth should be subjected to a steady flow of water to wash away as much blister gas as possible before any other treat- ment is applied. It is important not to direct a power- ful stream of water on the area until the bulk of the liquid blister gas has been removed, otherwise splashing and contamination of objects in the vicinity might pccur. A steady jet of water is required, and it should be allowed to flow over the whole area for 10 minutes. A light sprinkling of dry bleaching powder should then be distributed over the area and thoroughly brushed into the surface for five minutes, care being taken not to omit the gutters through which the first wash- ing water drained away. The hosing down should then be repeated with a more powerful stream.
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