> Note: Avoid portable air cleaners and furnace/HVAC filters that intentionally produce ozone. Ozone is a lung irritant. Note that in some cases, air cleaners that contain electrostatic precipitators, ionizers, UV lights without adequate lamp coatings, and plasma air cleaners may have the potential to emit ozone. Both the California Air Resources Board and the Association of Home Appliance Manufacturers maintain lists of air cleaners that have been tested and shown to emit little or no ozone.

from: https://www.epa.gov/indoor-air-quality-iaq/guide-air-cleaner...

following the link to the california one you get:

> Electronic: Air cleaners that are listed as "Electronic" may be capable of generating small amounts of ozone, but have been tested and found to produce an ozone emission concentration less than 0.050 parts per million. This category includes ionizers, electrostatic precipitators, PCOs, hydroxyl generators, devices with UV light components, and other electronic air cleaning technologies.

I imagine electrostatic precipitators would fall into that category