To whom it my concern,
I did a little on line research and found these web sites most interesting and relevant ;
www.livestrong.com/article/125263-hot-tubs-itchy-rashes/
https://medlineplus.gov/ency/article/001460.htm
epibulletins.dhss.alaska.gov/document/display?documentid=1743
Personally - I have found putting some lemon oil into my E vitamin oil and applying to the areas of concern works for me. Lemon oil is in most grocery stores and is cheap. Vitamin E oil is in most health food stores or the medicine section, and is not cheap but worth it.
Glad to help !