My concern is the number of chemicals in food products. As a teacher in the 70s, I had no students with peanut allergies and not a single inhaler. Now you can’t take anything with peanut into a school building and school secretaries keep drawers full of student inhalers.
Albuterol, the inhaler I use to live, was approved for commercial use in the UK in 69 and wasn't approved in the US until the 80s. So yeah, of course you didn't see it in the 70s.
I went to the hospital multiple times as a child in the early 90s gasping for air. If you are seeing more kids with inhalers it's because they aren't dying, unable to breathe, before they reached school age. Or factors like our age being worse, not food chemicals