Air we breathe is part of the atmosphere, the gas mixture covering the globe. This mixture of gases ensure life on earth and protects us from harmful rays of the sun.
The atmosphere consists of about 10 different gases, mostly nitrogen (78%), and oxygen (21%). That remaining 1% consists of argon, carbon dioxide, helium and neon. All are gas neutral, ie not react with other substante.Mai there are traces of sulfur dioxide, ammonia, carbon monoxide and ozone (O3) and harmful gases, smoke, salt, dust and volcanic ash.
Natural balance of atmospheric gases was maintained for millions of years, is now threatened by human activity. These dangers would be the greenhouse effect, global warming, air pollution, ozone depletion and acid rain.
Over the past 200 years global industrialization disrupted gas ratio needed for atmospheric balance. Burning coal and natural gas led to the formation of large amounts of carbon dioxide and other gases, especially after the end of last century appeared the car. Development of agriculture caused accumulation of large amounts of methane and nitrogen oxides in the atmosphere.
greenhouse effect:
Existing gases in the atmosphere must retain the heat produced by sunlight reflected from Earth. Without it the Earth would be so cold oceans would freeze supporters and people, animals and plants would die.
But when the ratio increases because of pollution gases called greenhouse gases, it is retained too much heat and the whole earth becomes warmer. For this reason in our century the global average temperature has risen half a degree.
Scientists believe that this increase in temperature will continue, and by expectations, by the middle of next century will come to value from 1.5 to 4.5 degrees C.
By some estimates, today over one billion people breathe badly polluted air, especially carbon monoxide and sulfur dioxide from industrial processes. For this reason, the number of the chest-lung disease, especially among children and the elderly, is increasing. As does the frequency of skin cancer is increasing. The reason is damaged ozone layer, which no longer retains harmful ultraviolet radiation.
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