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144
Report of the Medical Officer of Health.
that, if found necessary hereafter, intercepting traps could be
introduced and fresh air inlets provided.
It would probably be necessary to obtain a special dispensation
from the London County Council, whose By-laws
require the provision of interceptors.
H. J. MARTEN,
P. DODD, Surveyors.
27th January, 1903.
REPORT OF MEDICAL OFFICER OF HEALTH.
The ventilation of sewers is a subject that has for many years
engaged the attention of sanitarians, and many appliances have
been invented to deodorise or destroy the effluvium which indisputably
exists in many sewers, but these have not in any instance
proved satisfactory.
That ventilation is necessary is certain, in spite of the fact
that in two towns at least, viz., Bristol and Burton-on-Trent the
sewers are unventilated.
In properly constructed sewers with a good fall the amount
of ventilation required may not be great, as the necessity for it
does not exist to the same extent owing to the fact that there is
or ought to be no decomposition, but in old brick and pipe sewers
where deposit occurs through subsidence or other causes the
amount of decomposition is great and gives rise to effluvia offensive
in the highest degree. These effluvia consist of a complicated
mixture of various gases such as sulphuretted hydrogen,
sulphide of ammonium, and carbon bisulphide, along with still
more complex carbo-ammonical gases and organic vapours the
composition of which is unknown. In addition to these carbonic
acid gas, nitrogen, and marsh gas are also present but these are
not to any extent the causes of the offensiveness of sewer air.
Whether the inhalation of this offensive gas is the cause of
any definite and specific illness has not, in my opinion, been
conclusively proved, but that it does give rise to headache, nausea,
sickness, diarrhoea, and sore throat there is no doubt.
The methods adopted in London generally to abate the
nuisance arising from sewer gas are similar to those adopted in
this Borough, viz., surface ventilators in the middle of the