Covid can hang in the air like smoke, so basically any public indoor space, and any busy outdoor space. One sick person shedding virus, whether they present as sick or not, can fumigate a small area with covid for a while. It's best to assume there's covid around even when cases are low.
A small room with a few people? I don't worry about it that much outside of covid peaks, personally, but it kinda depends on how much you trust them to not lie about symptoms or recently being around someone sick.
If peer pressure or malaise of not doing stuff gets the best of you (this happened to a few people I know who are otherwise pretty covid aware still), at the very least look into nasal sprays like betadine.