Ozone in the upper atmosphere is a major factor in making life on the earth possible. But it contributes to air pollution in the lower atmosphere. Ozone is used commercially in water purification processes and as a bleaching agent. Ordinary oxygen molecules have two oxygen atoms. Ozone molecules have three.
Ozone is produced naturally through photochemical and electric discharge reactions.
Photochemical production occurs when high energy radiation from the sun strikes ordinary oxygen molecules in the upper atmosphere. Electric discharges, including lightning and sparks from motors, also convert ordinary oxygen to ozone. Ozone is produced commercially by electric discharges in a machine. Ozone has a molecular weight of 47.998. Pure ozone is a pale blue gas that has a sharp, irritating odor.