The permissible exposure limit for ozone is 0.1 PPM.

The IDLH (Immediately Dangerous to Life and Health) level for ozone is five ppm.

That's half of chlorine which is 10 ppm.

Most major brand air purifiers put out a very minimal amount; the ionization is beneficial because it makes the really tiny (and thus most hazardous) particles clump and fall/stick to surfaces faster.

It's the offbrand units that generate lots of ozone to make people think they're "doing something", and commercial ozone generators for car/room deodorizing, that you have to be extremely careful with. Those need to be set up and then the room left for hours for the ozone to react with stuff, and then ventilated thoroughly.