Produces clean, nontoxic, oil-free smoke to quickly find air-flow leaks in heat exchangers, air ducts, chimneys, tanks, boilers, and piping. Won't stain clothing or building interiors. Contains no explosives. Also used for fire drills and to test smoke alarms Warning: This product can expose you to chemicals which is [are] known to the State of California to cause cancer and birth defects or other reproductive harm.