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27
The smoke and sulphur dioxide are both measured in microgrammes
per cubic metre.
Since the above constitutes a major change in recording, it is thought
that a review of the previous years' records may be appropriate. Accordingly
the charts on pages 30 and 31 have been got out. Those on page 30
show the smoke records over the past seven years—highest, lowest and
1961 figures of (a) the monthly average and of (b) the extreme recordings
in periods (of maybe one, two, three, or perhaps more days) during
those months.
Commentary. It will be seen from the charts showing the monthly
average (left hand side of the page) that smoke in 1961 was, apart from
a bad December, as low as it has been in the last seven years. In the
south (Downham depot) in fact, it was below the previous minimum
for most of the first half of the year. With regard to the highest and
lowest readings in the months (right hand side of the page) it will be
seen that the lowest readings are in the main the lowest for the seven
years, while the highest readings (with the exception of November and
December) are well within the previous highest for those years. In
other words 1961, except for November and December, was a reasonably
satisfactory year for smoke pollution in spite of the poor weather. The
cold spell in December, however, blotted the copybook.
The charts on page 31 show the deposit gauge records over the
past nine years, and the highest, lowest and 1961 monthly figures for
insoluble deposit, soluble deposit, and for sulphur.
Commentary. It will be seen that with regard to insoluble deposit
(mainly, grit, smuts, dust) Pool Allotments shows high maxima but
quite satisfactory minima ; the 1961 line was mediumly placed. Verdant
Lane shows lesser maxima, slightly lower minima, and, for 1961, again
a medium amount. Wearside Road has an intermediate position with
regard to maxima, and a low position for minima, the 1961 line being
again medium. The Brockman Rise graph has more interest : it deals
only with results over 3 years, but the 1961 figures show that for many
of the months of 1961 the insoluble deposit was below the previous
minima. December was exceptional. The gauge was placed in an area
which became smoke-controlled in 1959.
With regard to soluble deposits (a measure more of general pollution)
there is not so much difference between the maxima and minima,
nor between the various stations. Brockman Rise again however shows
the lowest pollution for 1961, except again for the bad month of
December.
On the amount of sulphur deposited (which is some indication of
the degree of general smoke and house congestion in the neighbourhood)
the summer 'trough' is always obvious. Pool Allotments was quite
satisfactory in 1961 and, in relation to previous years, so was Wearside
Road. Brockman Rise again, except for the early part of the year, was
low, but on the whole no lower than Verdant Lane.