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48
of 55,000 or more British thermal units per hour. This Section,
which does not apply to furnaces designed solely or mainly for use
for domestic purposes, is designed to ensure that any new furnaces
installed shall be, so far as is practicable, capable of being operated
continuously without emitting smoke. Eight such notifications
were received during the year.
Chimney Heights
A Circular and Memorandum from the Minister of Housing and
Local Government places a duty on local authorities to satisfy
themselves that new chimneys, to which Section 10 of the Clean
Air Act applies, will be high enough to prevent, so far as practicable,
smoke, grit, dust or gases emitted from the chimneys from
becoming prejudicial to health or a nuisance. Guidance is given
on the calculation of chimney heights, based on the amount of
flue gases which the chimney is expected to emit as a function of
the maximum rate of emission of sulphur dioxide. This is not
applicable to all chimneys and affects only: —
(a) chimneys of industrial boiler plant of maximum continuous
rating greater than approximately 650 lb. steam/hr. and not
exceeding 450,000 lb. steam/hr. or
(b) to chimneys serving furnaces burning fuel at a maximum
rate greater than approximately 100 lb./hr. of coal or
50 lb./hr. of oil, and not exceeding 50,000 lb./hr. of coal
or 30,000 lb./hr. of oil.
The method of calculation advised by the Minister is to be
regarded more as a guide rather than a mathematically precise
way of reaching a final decision on chimney height and is open
to modification in the light of particular local circumstances.
During the year discussions took place with the Borough Architect
on this problem, following which a meeting with other authorities
was held to endeavour to arrive at an acceptable standard for the
Inner London area. The problem is still under consideration.
Measurement of Atmospheric Pollution
Daily readings of the concentration of smoke and sulphur
dioxide (S02) in the atmosphere were continued during the year
at the four stations throughout the Borough where recording
apparatus has been installed. A record of these readings for the
year under review is given in Table 1 and details of smoke and S02
concentration during the year is shown in Table 2. The readings
are taken by members of the staff of the Department who pass the
information to the Department of Scientific and Industrial Research
for collation with data received from authorities all over the
country.