Dr. Clo's Sterilization Stick uses Chlorine Dioxide to sterilize the air from virus and microorganism. Patented nano filter ensures that Chlorine Dioxide is released in a controlled manner that disinfect and deodorize the air. Chlorine dioxide from Dr. Clo is safe to use which is certified by WHO, FDA, EU and KOREA. Dr. Clo Sterilization Stick is rated as CLASS 1 Medical device by FDA.