https://www.scientificamerican.com/article/why-do-smells-trigger-memories1/

Whenever I smell the pages of a brand new book, I am reminded of all the late night reading I did as a kid. I can even feel the soft fabric on the arms of my favorite reading chair and sense the quiet of a house where everyone else is asleep. The stresses of the day start to give way a bit to feelings of calm and focus. We have an armchair in my daughter’s room very similar to my childhood reading chair, but sitting in it doesn’t quite conjure up those memories as effectively as that new book smell.

And I am not alone! Anecdotally, many of us have had experiences where a certain smell—perhaps chlorine, fresh baked cookies, or the salty beach air—floods our brain with memories of a distinct event or location that we associate clearly with certain emotions.