as in the song, remember?
if you don't have an aunt,
you won't lose her
and if you don't live
then you don't, then you and no, then you will not die.
There is always a chance to get infected with something, even in a closed apartment a mosquito can fly through the ventilation, and there may be something in the tap water. but if the statistics of morbidity in the swimming pools were significant, they would have been clearly banned.
they use special disinfectants there, previously they simply chlorinated (sometimes excessively from which the skin was very dry and the eyes were inflamed), now it seems that they use something more gentle.
so heal the nerves and boldly strengthen the body.
Here is a very interesting but long article in English http://www.scs.illinois.edu/~mainzv/HIST/bulletin_open_access/v32-2/v32-2%20p129- 140.pdf
At the beginning of the 20th century, poliomyelitis became very widespread in the United States. There were high suspicions that it was transmitted through the pools. How often this actually happened is unclear. Chlorine treatment in particular has become widespread due to fear of polio.