The Hajj will require a pilgrimage going to Saudi Arabia, and there are some rules that people should follow to ensure that they are following the rules that will allow them to be Holy for the event. The male Muslims are supposed to make sure that they are clean. They are not allowed to cut their hair, beards, and nails. They are also not allowed to use anything that is scented.
This means that even if they would use deodorant, they have to get the unscented variety because this will make a lot of difference. People are also not allowed to smoke, swear, and engage in any physical activity while the pilgrimage is taking place.