Smell is easily the most important sense you can use to your advantage as a writer. It’s also one of the hardest to write, as smell is a rather subjective thing. Two people don’t have the same responses to smell. And that’s good and bad for you. Most of our associations with smells are formed when we’re children. Happy memories of fresh cut grass or heartbreaking ones of formaldehyde. The fresh sensation we get from petrichor. How optimistic things seem somehow once we experience it.
Smell is tricky to write because your first memory of the smell may not even be concrete. You may just have the vague memory of the smell of biscuits baking and have it be a happy one. You may not know why the smell still makes you happy, but it does. You may have an aversion to a smell because of a negative memory. Like the smell of chlorine making you feel ill because of a near miss drowning in a public swimming pool. A perfume may make you cry because your grandmother wore it and she’s not with you anymore. And that may not even be something you remember.
A vaguely related anecdote. For decades now, I’ve had an odd memory of the smell of fish food. This is odd because we never had fish. No one in my family had fish. None of my friends had fish. Eventually the memory sort of faded. Until a recent trip to visit family up north. Lovely damn yankees that they are. My aunt mentioned my grandmother’s cousin. And how much I liked him when I was very small. I don’t very clearly remember his appearance, I must have been three or so the last time I saw him. And the smell of fish food came back into my mind. And it was in association with him, and the time he begged for change from our entire family so he could buy fish food and let me feed the fish. And it made me happy. Long story short (too late), the memories you have of smells can have a powerful impact. Even if you can’t quite make out why.
Smell can affect our emotional state very easily. Most people, for example, find the smell of vanilla very comforting. It’s easier for them to relax when that smell is around them. Studies have also shown that some smells can make you more productive, like the smell of citrus fruits. A smell that comforts one person can make another shake in fear. Sure, your lovely grandmother wore that jasmine perfume, but so did that guy’s abusive aunt. And now he cries every time he smells jasmine.
Smell can also have a big impact on your physical state. I, for one, get incredibly nauseous when I smell vinegar in nearly any quantity. It’s a charming quirk of mine, but that feeling and that reaction can be used to your advantage. Write about how something particularly gross also smells particularly gross. If you’re doing it right, your reader will end up just as nauseous as me making a paper mache volcano. And you’ll have done your job right.