I found some good information when I looked to see how our bodies use chlorine. I found the following on a chemistry site. I think it explains why I'm (and other people) smelli chlorine when having sinus problems. It probably means my immune system is doing it's job.
Human Body: Immune System
"In the immune system, which is charged with fighting off the daily invasion of germs, chlorine is there to lend a hand. When infections take place, hypochlorite -- a chlorine-containing compound which is a well-known disinfectant -- forms in white blood cells. Hypochlorite itself attacks the germs, or helps to activate other agents that do the work."
I hope this this helps to ease others worries
(link to more information)