About two thirds of the human body, and nine tenths of water, is oxygen. The gas is colourless, odourless, and tasteless. It is formed from electrical discharges or ultraviolet light acting on O 2 . Aerosols in the atmosphere have a detrimental effect on the ozone layer. Large holes in the ozone layer are forming over the polar regions and these are increasing in size annually.
Undiluted ozone is bluish in colour.
Oxygen is very reactive and oxides of most elements are known. It is essential for respiration of all plants and animals and for most types of combustion. Strange Matter cartoon included by kind permission of Nick Kim at the University of Waikato , New Zealand. All rights reserved.