Why do you get sick in the rain but not in the pool?

Answer 1

The popular saying "If you stand out in the rain, you'll catch a cold." is a myth. However, the myth has some base in reality. Water lowers a person's core temperature, so if you stand out in the rain for a while, your body will likely cool down. (Rain also tends to be cooler water.) Now, here is where the myth comes into play: if you stand in the rain for a sufficient amount of time (or snow, or sleet, of hail. Any type of precipitation, really.) your body temperature will be lowered below normal, and when your temp drops below normal, it becomes easier for viruses and bacteria to attack. Since you go swimming when you are hot, your body temp is not as likely to drop below normal, thus you are less likely to become ill.

A second explanation is the pool water itself. The pool is filled with chemicals to keep it clean enough to swim in. The rain does not have it, and the water, if it gets into you (vie cuts, eyes, mouths, or other body openings) can make you ill. However, swallowing pool water can also make you sick, if you swallow too much of it, due to it's high concentration of chlorine.