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80
solution of ortho-dichlor-benzene will produce 90 per cent. efficiency.
However, both these substances are fraught with such great danger
that they can only be used by men specially trained, and the premises
must be vacated before disinfestation. In so far as we in Hampstead
have no temporary alternative accommodation to offer to the tenants
we have not used this method, although I understand certain Boroughs
have already done so. An investigation was made into 76 cases which
came to our notice during the twelve months ending 31st October, 1936,
and it was found that we received only 5 requests for repeated disinfestation
as our first application had not proved sufficiently effective.
Additional legislation would be necessary in order to empower Metropolitan
Borough Councils to provide temporary accommodation for
persons removed from their dwellings whilst their premises were
undergoing disinfestation; but it would appear that at the present
time there is only a limited need therefor in Hampstead. Alternative
accommodation for tenants is required only if HCN or concentrated
ortho-dichlor-benzene is used, and in any case the use of these substances
is subject to the following disadvantages:—(1) only men
specially trained can use these products, and there is no one on the
staff of the Council who is trained in their use; (2) even with the
greatest precautions there must always be certain dangers, not only to
the workmen themselves but to the occupants of adjoining buildings,
owing to the likelihood of the gas permeating through the defective
structures; (3) accommodation would have to be provided, not only for
the particular dwelling to be disinfested but also for the occupants
of neighbouring dwellings.
When the "Westcroft" Housing Estate was ready for occupation,
arrangements were made whereby a specialist firm undertook the
removal and disinfestation of the effects of all families removing to
the Estate, and for other necessary work to be carried out by the
Council's disinfecting staff. Bugs were eradicated from furniture,
bedsteads, etc., by subjecting them to a 2.5 per cent. concentration by
volume of Hydrogen Cyanide for four hours in specially constructed
vans. Ventilation was then carried out until a series of tests made
with Sieverts and Hermsdorf reagent showed no dangerous concentration
of H.C. remaining. Generally the procedure adopted was as
follows:—