Just.a quick post here. Pools are sometimes either not clean enough (and thus contain possible pathogens) or too clean (well, more importantly might have too much of cleaning chemicals like chlorine).
Outbreaks of crypto, a parasitic infection linked to pools, doubled from 2014 to 2016, and 4,800 people visited ERs for pool chemical-associated health issues in 2012.
Source: CDC warns about parasites, toxic gas at public pools – CNN.com