I put this in my basement and let it sit for 2 hours. After 4 hours I returned home. The toxic smell of ozone was so strong and nauseating that family members felt nauseous and had headaches. There is nothing clean and fresh about this scent. It's a horrible putrid toxic chemical smell that my body chemistry reacted to immediately. We turned on the fans and opened the windows, but unfortunately the smell was overwhelming. Finally, around the seventh day, the ozone smell began to dissipate and the musty basement smell returned. It is clear that the strong toxic odor of ozone masked the mustiness in the basement for about a week. In my opinion, after turning on this device, you should be away from home for at least 7-10 days. Even if you only use it in one room, the smell spreads throughout the house. I can't imagine using this in a car. It cannot be healthy and should be banned. I strongly recommend that you read all reviews before purchasing, especially the low rated ones. I returned it.