Let's start where you need to, by correcting a misconception some of the salt system (SWCG) companies have encourage: SWCG are just ANOTHER way of adding chlorine to your pool, and there's nothing 'natural' about it. Essentially, a SWCG turns YOU into a micro-sized manufacturer of chlorine!

That said, SWCG's can help you maintain your chlorine levels better, and that can improve water (and air) quality.

The topic of asthma and chlorine is one I know a great deal about. My older son was both a severe asthmatic and eventually, a regionally recognized distance swimmer. There were pools that were maintained rather poorly, and that had poor air systems, that he couldn't swim in (at least, not fast), like the Tracy Caulkins center in Nashville. And there were pools he was VERY fast in, like the OLD pools at UTK or Alabama, which were well maintained AND heated with 100% outside air.

But, the topic is very complex, and the solutions aren't simple. Here's what you need to know for a start:

1. Asthma is NOT an issue, in OUTDOOR pools that are (a) well maintained (our way!) and (b) in full sun. During the time my son swam most, I maintained most of the large outdoor competition pools he swam in, in the Chattanooga area. He NEVER had a problem in one of those. It was only indoor pools, or badly maintained outdoor pools.

2. There is NOT a single 'gadget' or chemical that fixes the problem on indoor pools. If you want two key items. One is an air-to-air heat exchanger that constantly blows fresh warm air over the pool, and exhausts warmed but contaminated pool air. The other is UV irradiation system, which breaks down (with chlorine) some of the chemicals that form when chlorine interacts with people 'goo'.