non-smoker
A person who does not smoke tobacco. Neutral, factual term.
I'm a non-smoker, so I don't like cigarette smoke.
This restaurant has a non-smoker-friendly environment.
喫煙者 means 'smoker', the opposite of 非喫煙者.
禁煙者 refers to someone who has quit smoking, while 非喫煙者 simply means someone who does not smoke (including those who never started).
Compound of 非 (hi, 'non-') + 喫煙 (kitsuen, 'smoking') + 者 (sha, 'person').