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199
From this table it will be seen that the air of Bakehouses is,
on occasion, more than 20 per cent. drier than outside air. It
will be noticed that these observations were made in the
Bakehouse after all the work had been done. In order to test
the matter during the process of baking, examinations were also
made early in the morning, and one such reading may be added
here
Time at which Readings were taken
in Underground Bakehouse.
Relative
Humidity inside
Bakehouse.
Relative
Humidity outside
Bakehouse.
Percentage
Difference.
Early morning, work proceeding.
66 92 26
Early morning, hatch of
bread heing drawn from
oven.
58 92 34
Afternoon, work finished 52 57 5
Other examinations made in the early morning whilst actual
work was going on gave readings showing similar results to the
above. In a general way it may be said that when no work is going
on the average difference in percentage between the humidity of
the inside air and outside air is about 10; when work is going on
about 24that is to say, the air of the underground Bakehouse
contains 24 per cent, less moisture than the outside air.*
(c) Bacteriological Examination. A simple comparative
examination of the number of bacteria present in the air of four
typical underground Bakehouses and one typical above-ground
was also made. In each of these Bakehouses, whilst work was
going on, three agar-plates were exposed for 30 minutes.
One plate was placed on the floor, one on the table or trough
¤ It should not be forgotten that the differences of temperature and
humidity between the Bakehouse air and the outside air affects the
exchange of air between the two, and therefore the ventilation of the
Bakehouse and the degree of CO2