Recipe(tried): How to remove the mildew smell from a dryer

I had the same problem when I retrieved an un-used dryer
from my niece. I was afraid to use the dryer because it had a musty smell to it, and when I finally did use it, the
smell hung in the air throughout the house...My solution was simple...I put about a half cup of baking soda in a plastic picnic cup and placed it in the dryer...after a few days the smell was gone...I couldn't believe it even though it did work, but being the cautious soul that I am, whenever I'm finished using the dryer, I always put that half cup of baking soda back in the dryer...change the baking soda just as you would a box in the refrigerator. Hope this helps.