Well after doing some research I have learned that they really can be safe if you learn how to operate them properly and you can learn how on damagecontrol-911.com. It is not hard really, just go out of the room while it is working and when it finishes that Ozone turns into air after 1-2h. It takes it a few hours to clean the room and it is great for removing the odors. Another plus is that it will also kill every insect that was in the room and you might've not known about them so far. Really great tool for keeping your house clean and I am seriously thinking about getting one.