What disinfection method does your pool use?

No doubt the vast majority use only chlorine. It's probably the cheapest? Others use healthier methods, such as ozone, UV, or salt water, etc, or a combination of two (often the healthier ones still need to combine with some chlorine). Some chlorine pools are way too chlorinated and the smell is very strong from afar and cause various health problems, others are better. I heard some European countries are more health conscious than the U.S. in this respect. If your pool doesn't use chlorine as the main disinfectant, I'd also like to know which country it is if you don't mind. Thanks.