system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why does cold air smell fresher than regular/hot temperature air?
gpt
Because it is easier to detect the taste/smell particles in warmer air/liquid/solidaterial. 
In the same way that if you eat or drink something cold, you don't taste it as strongly. The same particles may be present in cool air, but you are less likely to detect them.

Also, in warm environments, bacteria etc are more active and may contribute additional smells etc.