Traffic chemicals appear strongest on busy motorways with stagnant air, where people outside of cars don't spend much time.
Flower chemicals can cause problems but usually dissipate within 10 feet or so.
Fresh rain primarily eliminates free-floating chemical attacks and does not cause one itself.
Cooking is self-regulating because the person actively triggering the chemical emission is exposed much more strongly than people elsewhere even in the same room.
Grass can only be crudely avoided or mitigated during the seasons where it's problematic. (Thank God for COVID bringing awareness that masks make it physically easier to breathe.)
But perfume? You never know when you'll run across a person who chooses to be a targeted, walking violation of the Hague Convention. There's no way to mitigate this other than avoiding people entirely (which some people do choose to do, but which has negative side effects).
That said, in recent years I find the perfume from cleaning supplies or laundry supplies to be more problematic than the perfume from people.