Are home ozone units really bad for your health?

Be Careful w/ Ozone: If you have any respiratory problems or asthma, ozone may make them worse. So that would be a definite contraindication -- (do not use). Ozone, if used, must be used in well ventilated areas and only for short time periods.

Often - yes.: According to the epa, ozone air purifies should not generate an excess 50 parts per billion of ozone but many companies circumvent this by simply not calling their machines medical devices. The epa states that ozone is dangerous due to the potential for lung damage.