There are plenty of ways to monitor it. Most importantly of them are expensive. The sulfur smell was probably hydrogen sulfide. There are some draeger tubes for testing it, but if it is only occassional, that's part of the problem. There are labs that will test also, again for a fee. One other option that I haven't heard much about in awhile is the copper test strip that public lab was working on. It would give a good long term coverage. Can anyone give an update on the copper strip hydrogen sulfide testing?