Ozone (O3) is a key constituent of the troposphere.

Photochemical and chemical reactions involving it drive many of the chemical processes that occur in the atmosphere by day and by night.

At abnormally high concentrations brought about by man's activities (largely the combustion of fossil fuel), it is a pollutant, a constituent of smog.

Many highly energetic reactions produce it, ranging from combustion to photocopying.

Often laser printers will have a smell of ozone, which in high concentrations is toxic.

Ozone is a powerful oxidizing agent readily reacting with other chemical compounds to make many possibly toxic oxides.

The majority of tropospheric ozone formation occurs when nitrogen oxides (NOx), carbon monoxide (CO) and volatile organic compounds (VOCs), such as xylene, react in the atmosphere in the presence of sunlight.

NOx and VOCs are called ozone precursors.

Motor vehicle exhaust, industrial emissions, and chemical solvents are the major anthropogenic sources of these chemicals..

For more information about the topic Tropospheric ozone, read the full article at Wikipedia.org, or see the following related articles:

Ozone layer — The ozone layer is the part of the Earth's atmosphere which contains relatively high concentrations of ozone (O3). "Relatively high" means a few ...  > read more

Nitrogen oxide — NOx is a generic term for the various nitrogen oxides produced during combustion. They are believed to aggravate asthmatic conditions, react with the ...  > read more

Atmospheric chemistry — Atmospheric chemistry is a branch of atmospheric science in which the chemistry of the Earth's atmosphere and that of other planets is studied. It is ...  > read more

Oxidizing agent — An oxidizing agent (also called an oxidizer or oxidant) is referred to as a chemical compound that readily transfers oxygen atoms or a substance that ...  > read more

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