Ozone is just good old oxygen, the stuff of life, but instead of two atoms of oxygen joined together, O2, ozone has 3, O3. Ozone is bad down here on earth, causing chronic lung damage to humans and billions of dollars of damage to crops. It is one pollutant which has not improved in urban areas over the last twenty years.
Ground Level Ozone
Ground level ozone is produced by chemical reactions between nitrogen oxides (NOx) and Volatile Organic Compounds from automobiles, solvents, automobiles, paints, automobiles and industrial emissions. Volatile Organic Compounds are also emitted by trees in sunlight. The Canadian Council of Ministers of the Environment, in setting a Canada wide standard for ozone, noted that more than half of all Canadians are exposed to high ozone levels. In the Fraser Valley the ozone is formed by local pollution, in the Maritimes transported from the US, and in the Windsor-Quebec corridor both local and US emissions do the dirty trick.
The Ozone Layer
Up in the stratosphere, 15 to 40 kilometres above the earth, ozone forms a crucial shield reflecting away about a third of the sun's radiation, enough to protect the life forms below. Ozone in the stratosphere is continually destroyed and reformed, in a natural balance. But chlorine, delivered to the skies by long-lasting industrial chemicals used as solvents and for refrigerants and automobile air conditioning, (the CFCs or chlorofluorocarbons,) destroys the ozone molecules faster than they can reform. Ozone destroying chemicals are the subject of an International Treaty for their phase out, The Montreal Protocol, but it will be about fifty years before the ozone layer returns to its former robust self. Meanwhile jet aircraft deliver a steady attack of nitrogen oxides which also destroy the ozone layer. Pilots and cabin crew are at special risk of skin cancer.
The theory is that pollution will lead or even has led to the earth's over-heating. As we emit pollution into the atmosphere, the incoming radiation from the sun becomes trapped in the blanket of pollutants which hold the heat as the planet warms. It is important to note that some of the chemicals used to replace the ozone destroying CFCs, such as HFC-23 and SF6, are extremely strong and very persistent greenhouse gases.
- Carbon Dioxide
- Nitrous Oxide (N2O)
- CFCs & other halocarbons
- Water Vapour
- Aerosols (Fine Particulate) from Sulphur Dioxide