I've seen the Preval kits and have heard good things. The sprayer really isn't a worry for me though. It's the safety concerns that I was more asking about. If I need a fresh air system for me then I probably should do this in my backyard with neighbors' houses 25 feet away. But if the basic automotive clear isn't hazardous, or at least not hazardous enough to cause a problem with this kind of application, then I'm good with it.