A fan will do nothing toward smell unless it is an exhaust fan sucking air out of the closet to outside of the house. If you dont care about smell and your not trying to hide it then you shouldnt have any worrys. Smell also largely depends on how many plants your growing. if your only growing a few then dont really worry but if your growing like 30 then the whole house is going to reek come bud time. :thumbsup: