How being in the rain CAN make you sick
If you believe you have caught a cold or some other type of illness after being in the rain, you may be quick to blame the cold, rainy weather. As mentioned earlier, the rain itself is not responsible for making you sick, but it may have increased your risk of being exposed to an illness for the following reasons.
"Lowered body temperatures
Cold and rainy weather lowers our body temperature, which can weaken our immune systems and allow us to fall ill easier. It also can increase your risk of infection and make it more difficult for your body to fight the infection off. Extremely cold temperatures can also make us more susceptible to serious illnesses like hypothermia -- a serious condition where the body loses more heat than it can make."
Bottom line is that being in the rain (which does not carry the flu or cold virus) is not a healthy activity for anyone, especially when wearing a wool uniform that will retain the water that will drop the wearers body temp compromising the immune system making the person more susceptible to catching the flu or a cold. If you want to deny that fact, then that is your problem; just don't subject your band students to you same ignorance -- it's not healthy for them.