Ask HN: Scent Sensitivity?

I have several people around me who are sensitive to different scents (chemicals and perfume). When exposed, they experience headaches, and sometimes find it hard to function at all.

I never remember hearing about this at all when I was growing up. Is this much more prevalent than it used to be?

And if so, why? Is it because of a change in the chemicals used to create the scents (or the chemicals that the scents are trying to cover up), or is something making people more sensitive than they used to be?