– When the level of chlorine in pool water becomes elevated beyond a safe (and recommended level), it can become toxic to humans. Anyone who has been swimming with their eyes open and experiences burning, red, itchy eyes knows what we are talking about. “Acute over-chlorination in pools causes swimmers to experience moderate to severe eye irritation. They experience burning in their nasal passages and mouth if they inhale the over-chlorinated water. Swimmers also develop rashes and irritated skin when pool water pH becomes unbalanced.” Bottom line: if you experience any unpleasant side effects after swimming in a pool, thoroughly cleanse your skin and your eyes to alleviate any pain and do not go back into the water until you have tested it and you know the chlorine levels are not too strong.