View report page

25
Swimming baths
At the beginning of the summer, as a result of two cases of infantile
paralysis being notified, I thought it desirable to suggest that all the
public swimming baths should be equipped with the apparatus necessary
for breakpoint chlorination. This enables a very much higher amount
of chlorine to act on the water, and because of some differences in the
chemical reactions the effects on persons bathing (such, for example,
as possible slight smarting of the eyes) are even less than when a small
amount of chlorine is used.
Although swimming baths have never definitely been proved to be
the vehicle of poliomyelitis infection (infantile paralysis) yet they
cannot altogether be excluded as there is some evidence that poliomyelitis
infection may be water-borne. Nevertheless experimental work with
the virus of the infection has indicated that it is very rapidly killed by
free chlorine even if this is present in a concentration of a little less than
one part per million, and therefore if the free chlorine contained in
swimming bath water is kept over one part per million the chances of
transmission of poliomyelitis infection through swimming bath water
are negligible. It was for this reason that I recommended that breakpoint
chlorination should be installed, because the public is very sensitive
during the time when poliomyelitis cases occur frequently, and in many
areas (due I think mainly to this public sensitivity) swimming baths
have been closed. We did not close our baths in 1947 when we had a
fairly large number of cases, although we certainly advised parents in
general against allowing their children to take excessive exercise, such
as competitive swimming, as if the child were already infected with
the virus this could cause a very severe degree of paralysis of the muscles
involved. We therefore aimed at getting this year a residual chlorine
content of between one and two parts per million as, if this were done,
I was quite satisfied there would be no need to close the baths even although
we might have a large number of cases of poliomyelitis. During
the season the Council installed the breakpoint apparatus at all the baths
in which it had not previously been placed.
The following colorimetric tests are taken by the staff of the Baths
department at 9 a.m., 1 p.m., and 6 p.m., each weekday and at 9 a.m. on
Sundays, and the results are recorded on log sheets for the purpose:—
1. Free residual chlorine.
2. pH value.
Periodically quantitative tests are taken to determine the bicarbonate
alkalinity.
Samples are also taken by Health department staff and submitted
periodically to the Public Analyst for chlorine content. The following
is a summary of the samples submitted during the year:—
Lady well first class 8
second class 9
Forest Hill first class 2
second class 4
Downham 5
Bellingham 2