RE: Wildfire smoke/ash affecting pool water.
I’m not sure the chemistry or volume is there for PM2.5 to affect chlorinated pool water. Ash and other combustion products aren’t very harmful to skin, especially in such low concentrations. The only thing I can see happening is the increase in carbon making the water slightly more basic, which may allow more bacteria to proliferate. But this should be combated by a competent pool crew, and would be apparent pretty quickly on smell alone.
I would be more concerned about open water ponds/lakes, not only because they are more delicately balanced but also because of the continued runoff concentrating contaminants into the lake. The threshold for potable drinking water is much much lower than a safe swimming water though.
I don’t know about the airborne properties of chemical retardants, but if you live very close to an active wildfire that may be cause for concern.