• Oxygen organised in molecules of three oxygen atoms rather than the usual two


  • noun a poisonous form of oxygen found naturally in the atmosphere which is toxic to humans at concentrations above 0.1 parts per million

Cars & Driving

  • noun a strong oxidizing agent (often produced by sparking from electrical apparatus, such as arc welding equipment); particularly harmful to tyres


  • Triatomic oxygen (O3), an unstable form of oxygen that is produced by ultraviolet activity and electrical discharges and is used as an oxidizing agent, a deodorizer in air-conditioning and cold storage systems, and as an agent for stemming the growth of bacteria, fungus, and mildew. Excessive concentrations of ozone are poisonous to humans.


  • A poisonous and highly reactive blue gas whose chemical formula is O3, making it an allotropic form of oxygen. It may be formed, for instance, when oxygen is exposed to electrical discharges, or in certain photochemical reactions. Ozone has a characteristic odor, which is sometimes detected near a lightning stroke, and although it is toxic, a layer of ozone in the atmosphere helps shields living organisms from excessive ultraviolet radiation from the sun.


  • noun a sterilising solution used in chemical ice


  • noun a gas present in the atmosphere in small quantities, which is harmful at high levels of concentration


  • noun a harmful gas formed by the reaction of industrial pollutants with sunlight, especially in large cites, that can damage bodily tissues and reduce a person’s VO2Max over time


  • acronymO3