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RIVERS POLLUTION
The following figures relate to action taken to prevent pollution of
surface water drains by sewerage.
Premises inspected by drainage inspection assistant 5,363
Re-inspections 1,296
Premises inspected by district public health inspectors 442
Re-inspections 651
Number of premises in which defects were remedied after service
of written or verbal notices 273
In 62 cases the soil drainage was found to be connected to the surface
drainage, and action was taken to remedy this. In 245 cases there was a
defect in the intercepting chamber, usually due to a cap being displaced
or missing, and these defects were also remedied.
ATMOSPHERIC POLLUTION
Deposited Matter
The extent of pollution by deposited matter is determined by examination
of the solid and liquid matter collected by the deposit gauges each
month. With the exception of the Wightman Road site (d) it will be seen
that the total solids deposited each month in Hornsey is appreciably less
than the average figure for the whole country as shown in table II. It was
felt that the high figures obtained at site (d), were not representative of
the area and on the 1st April this gauge was moved to a more unobstructed
position at the Electricity Sub-Station, Hampden Road. This may prove
to be a more representative site, and has so far averaged about 15 tons
per square mile, but insufficient time has elapsed to arrive at definite
conclusions.
Suspended Matter (Smoke)
Smoke is measured by passing a known volume of outside air through
a white filter paper, the darkness of the stain depending on the amount
of smoke in the air. The filter paper is changed every 24 hours, and the
density of the stain measured. From this information a simple calculation
gives the concentration of smoke which is usually stated in milligrammes
per 100 cubic metres of air.
Smoke concentration in the air in this Borough is shown to be appreciably
less than the national average concentration, the national figures
for 1956-7 being 21 milligrammes per 100 cubic metres, compared with
11 at Fortis Green and 15 at the Central Depot. No annual figure is yet
available for the Town Hall site but the winter reading of 20 milligrammes
may be compared with the national average of 27 milligrammes.
A great deal of the considerably greater smoke concentration in winter
is due to domestic sources.
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