answer:Without reading up on it… The moisture is changing the composition of the tablets by reacting with them, meaning they are not the original compound they’re supposed to be. This could effect their effectiveness, but honestly I dunno without reading further. I mean you’re supposed to mix them with water (and a much higher volume of it at that), so one would assume a small amount of water wouldn’t severely hamper their effectiveness. You are correct on the fumes, do not breath in chlorine gas fumes. They are very toxic. As far as drying them out, you could try taking the lid off during the day and letting it “air out” in a sense. Some of the moisture would go away, plus you would air out the fumes. If it really bothers you you could take a hair dryer to it, but I’d be cautious in that as heat tends to start a variety of reactions.