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196
Volumes of CO2 in
10,000 volumes of air.
Open air of streets in Finsbury (mean of six
analyses)
4.3
Air of typical above ground Bakehouses 4.9
Air of typical underground Bakehouses (mean of
eight analyses)
14.8
This shows a very high degree of vitiation, but perhaps not
more than might be expected under the circumstances. For we
have in addition to the underground position, a considerable
absence of ventilation and exceptional production of C02. There
is the respiration of the workers (yeilding about one cubic foot of
CO2 per man per hour*), the oven, the gas burners,† and the fermentation
of the dough. Whilst these conditions explain the
presence of the high degree of C02 they also emphasise the
imperative necessity of abundant ventilation wherever bread is
made, especially when it is remembered that the atmosphere is
one in which men are working for eleven hours each day.
Further, it should not be forgotten that the figures obtained
in respect of the C02, are in nil probability considerably below
the mark of what is usually present. The differences of temperature
and the various openings of the Bakehouse, both for
ventilation and for the exigences of the trade, admit of considerable
variation of the C02 actually found to be present, and these
conditions are in full operation when the shop is opened and
¤ Journal of Hygiene, 1902. Vol. ii., p. 430 (Haldane).
† A common gas jet, as usually met with in workshops and bakehouses
consumes from 5 to 10 cubit feet of gas per hour; and this amount of
ordinary English gas produces, in burning, from 2½ to 5 cubic feet of
carbonic acid gas. So that this amount of C02 is added every hour that
each jet of gas is burning (Haldane). Incandescent mantles use up much
less gas per hour than ordinary burners and yeild much more light. They
are therefore preferable in workshops. By the use of incandescent
electric light, all the inconveniences due to air vitiation and heat from
gas jets can be avoided (Haldane).