We are taught to use all our senses when we write narrative. But sight and sound usually predominate. Personally, I believe the sense of smell is our most powerful sense.
We all relate to the stench of garbage, or the aroma of Chanel No. 5. Smell adds a unique element to our writing, one which immediately indicates whether a scene is going to be pleasant or malodorous.
Think of smell when you’re describing a scene. But don’t overdo it. Smell is so powerful that one mention per chapter, or even every other scene, can be plenty.