Posted By Joe Ridley Hi there, It sounds like there are problems with the pool water treatment system and ventilation system. The cause of the chlorine smells is a build up of a substance called Nitrogen Trichloride which is caused when the ph value is too low and the combined chlorine too high. Nitrogen Trichloride is an irritant and can cause respiratory discomfort. Prolonged, frequent exposure of people bathing or working in such atmospheres can cause a number of eye, throat and chest symptoms that almost mimic flu. Do you have a pool engineer? He should be able to sort the problem out. The pool temperature should be around 29C with the pool hall temp one degree above that. Humidity levels should be between 50% and 70%. I would strongly recommend contacting the Pool Water Treatment Advisory Group - 01379 783678 for further advice, they should be able to point you in the right direction for correcting this problem, also you can order their publication "Swimming Pool Water Treatment and Quality Standards" which is the recognised standard for swimming pools. It contains all the standards required for the safe operation of the swimming pool water treatment. You may want to consider closure of the pool until this problem is solved, have any bathers been complaining as well? Hope this helps Cheers Joe