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40
Special Survey.—A concentrated survey of the atmospheric
pollution in the Borough was undertaken following continued
heavy grit deposit in the East Greenwich area.
The services of two Chemical Consultants were engaged
by the Council.
As a preliminary, permission was obtained from the owners
of the premises under observation, and samples of flue gases representative
of the actual emission from the chimney shafts were
taken at suitable points.
In order to obtain correlation between the dust emission and
the dust deposits which have given rise to complaints, a survey of
the Borough was made with a view to locating suitable positions
where the atmospheric deposit could be collected.
Twenty-two deposit stations were selected at distances ranging
from one hundred yards to one and quarter miles from the chimneys
in question. Grit deposited from the atmosphere was allowed
to fall into enamel trays—the dimensions of which were 18" x 14" x
2" deep—and was transferred with the application of distilled water
to bottles; and in all, 881 samples of grit were submitted for
analysis. The collections were made at the end of periods varying
from several hours to seven days, and were carried out continuously
during the six months from February to July.
The results were collated and the climatic conditions, including
wind direction and velocity and rainfall for the same periods, were
recorded.
During this special survey observations were regularly made
of the smoke emission from the chimneys concerned and from those
in the near vicinity.
Special maps of the Borough showing the positions of the
deposit stations were prepared.
The deposits during each particular period were marked on
a separate map for that period, and on correlation it was found
that (1) the particles deposited varied inversely as the distance
from the point of alleged emission, and (2) the amount of deposit
varied directly as the direction of the wind.
The analytical and microscopic examinations of the deposits
and their comparison with the materials deposited in the flue system
and extracted from the chimney gases left no room for doubt that
the former were derived from the solids carried by the chimney
gases.