The Truth Behind Ozone

This article presents the applications of ozone monitoring. What is ozone? How does it impact air quality? Why is it important to monitor ozone concentrations? What are the industrial applications of ozone?

Ozone (O3) is a triatomic molecule consisting of three oxygen atoms. It is a colorless gas with a pungent smell. Ozone at ground level – in the air we breathe – is an air pollutant and is not to be confused with the ozone layer in the upper atmosphere. Ozone in the upper atmosphere filters potentially damaging ultraviolet light from reaching the Earth’s surface. In the troposphere, near the Earth’s surface, human activities lead to ozone concentrations several times higher than the natural background level.

Ozone impact on air quality

Ozone is the main product of complex photochemical processes in the lower atmosphere involving oxides of nitrogen and volatile organic compounds as precursors. Ozone is a strong photochemical oxidant.

The main sectors that emit ozone precursors are road transport, power and heat generation plants, household (heating), industry, and petrol storage and distribution. The dominant issues determining short-term air

quality are nitrogen dioxide, particulate matter and ozone. All three pollutants are strongly related to the use of fossil fuels. Ground-level ozone (O3), unlike other pollutants mentioned, is not emitted directly into

the atmosphere, but is a secondary pollutant produced by reaction between nitrogen dioxide (NO2), hydrocarbons and sunlight. Sunlight provides the energy to initiate ozone formation; consequently, high

levels of ozone are generally observed during hot, still sunny, summertime weather. During the day, ozone concentrations will usually build up and peak in the afternoon. At night-time, ozone concentrations decline.