There is nothing like a refreshing swim, especially in peak summer. Jumping into a pool and cooling off as the gentle smell of chlorine comes off the water. However, if you are smelling the chlorine in a pool you might not actually want to be in it.
Most people know chlorine is a chemical that's added to pool water to sanitize it by killing off germs and bacteria. If you smell chlorine, it might be a reassuring odor since it lets you know that the water has been treated and is probably safe to swim in. It turns out though that chlorine mixed with pool water actually has no odor, and what causes the smell might have you thinking twice before taking a dip. That chlorine odor is actually the byproduct of a chemical reaction that happens when chlorine reacts with ammonia, which is very present in urine.
Pretty much, if you are in a pool with a strong chlorine smell, it means someone likely peed in it. Don't worry though, it isn't just pee in the water - ammonia is also in sweat and body oils, which are also in the pool. Making matters all the worse, when chlorine gets mixed with urine, the chlorine winds up no longer being able to destroy the bacteria it's meant to get rid of. So pools that smell of chlorine actually need more chlorine.
As for what to do if you smell chlorine at a pool, the Water Quality and Health Council suggests, "It is good advice, to stay out of the water when a strong chemical smell pervades the air around any type of pool, indoor or outdoor."