I also associate ozone with some electric motors, I think because they have brushes that arc during operation. Older power tools I encountered in the 1980s often did this, and you could see the blue arc if you looked into the vents at the right angle.

Photocopiers smell like ozone when they run if anyone’s forgotten the smell

Those are similar but sweeter. If I sterilize a room with UV it has a very distinct smell like nothing else aside from lightening and stun guns. I would UV the bathroom right now but then I have to vent the entire house and its 34F outside right now.