Does oxygen have a smell?

Never. Oxygen is an odorless and colorless gas, which means it does not have a distinct smell that our olfactory system can detect. The sense of smell is mediated by olfactory receptors in the nose that are activated by molecules in the air that dissolve in the mucus layer of the nasal cavity. While there are many molecules in the air that have a distinct smell, oxygen is not one of them. 

Here’s an interesting fact: Mice can sense oxygen levels in the inhaled air using specialized neurons in their noses. View Study.