Ozone
If you ever did any photocopying on the old machines, ozone is part of that smell profile.

Problem for me is that I went to the large Science Museum in Paris at an impressionable age and there was an Odor-torium, or similarly named, exhibit which matched images on a small cinema screen with puffs of scents and aromas, perhaps from canisters. The most disagreeable example - the one that would clear out the room - was a nature show where you wound up visiting a fox’s den. Bleaurgh!!! One of the constituent component smells of that noxious lair must be released during photocopying, I couldn’t be near a photocopier in action for years without feeling nauseous.