I used to put those humidifier and fragrance in my shoe cupboards and small spaces. In the past year, I have been reading up on charcoal products that helps to neutralize smell, or sort of act as a deodorizing agent. I know charcoal tablets also absorbs toxins in our body, should we have accidentally consumed products that may be toxic, such as food poisoning.
My mom places charcoal on her orchids. Charcoal helps the plant in retaining moisture thus allows the roots of the orchids to drink from it.
When I saw charcoal products for effective use in our car, I was shocked that these products cost about $7 to $20 for a small canister. So I had waited until I saw them in our friendly shop at the mall. They were really cheap at $2 each so I bought so many of them! They come in many variants, for the fridge, shoe cupboard, wardrobe, drawers and I even got a pack for orchids. And there is one that I have not decided to use or not. They are to be used in our water (consumption).. Just bought for fun, i guess!