Public pools are pretty safe from a microbial perspective because they crank up the chlorine and test the water for microbes. But hey, babies (and some adults) can’t help but urinate in the water amongst other things. So they keep the chlorine pretty strong, run filtration, and the sunshine helps. BUT as for breathing chlorine gas— not so good! Chlorine is VERY POISONOUS and soaking it up in the pool is disruptive to the thyroid, because it fills the iodide/iodine receptors. The same goes for bromine. It interferes with the thyroid.  The best choice is to have your own pool— salt water, ozonated, etc. If you choose to swim in a chlorinated pool, rub coconut oil on your body beforehand to provide a buffer that will prevent the chlorine from being absorbed by your skin (to an extent).