it is scorched air, burned oxygen.I use a grow tent I found on Amazon. I ran two ducts intake and exhaust with fans on them. After I run the ozone I clean it with fresh air before I go back in. When I first got the ozone machine I tried it in a closet, the whole house filled up which what smelled like scorched air.
Amazon.com: VIVOSUN 48"x24"x60" Hydroponic Mylar Grow Tent with Observation Window and Floor Tray for Indoor Plant Growing - 4' x 2' : Patio, Lawn & Garden