2020-08-03 Ozone SafetyOzone is a non-toxic and safe gas. When the concentration is higher than 1.5ppm, ozone stimulates human respiratory system, Ozone Association formulates safety and health standards: (1ppm = 1mg / m3). International Ozone Association: 0.1ppm, 10 hours exposure. USA: 0.1ppm, exposed for 8