Ozone

Ozone (O₃), or trioxygen, is a molecule consisting of three oxygen atoms. It is a pale blue gas with a distinctively pungent smell. It is an allotrope of oxygen that is much less stable than the diatomic allotrope (O₂), breaking down with a half-life of about half an hour in the lower atmosphere, to normal dioxygen. Ozone is formed from dioxygen by the action of ultraviolet (UV) light and electrical discharges within the Earth's atmosphere.

Formation and breakdown

Ozone is formed in the Earth's atmosphere when oxygen molecules become dissociated by solar radiation into individual oxygen atoms. These atoms can then combine with oxygen molecules to form ozone. The process is called the ozone-oxygen cycle.

Ozone can also be created by electrical discharges, such as lightning, and by certain chemical reactions. For example, ozone is produced in the photochemical reactions that result in smog.

Role in the atmosphere

Ozone plays a crucial role in the atmosphere. The highest levels of ozone in the atmosphere are in the ozone layer, a region located in the stratosphere several kilometers above the Earth's surface. Here, ozone absorbs most of the Sun's high-frequency ultraviolet light, which is damaging to life on Earth.

Health effects

Exposure to ozone can have various health effects. It can cause breathing problems, trigger asthma, reduce lung function and cause lung diseases. In addition to these, it is also a potent greenhouse gas, with a global warming potential much higher than that of CO₂.

See also

• Ozone layer
• Ozone depletion
• Ozone-oxygen cycle
• Greenhouse gases
• Air pollution

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