THERE ARE DIFFERENT FORMS OF POLLUTION:br />
a) air pollution
The air is polluted by the exhaust fumes of cars. The dangerous substances are carbon dioxide, lead, nitrogen, sulphur dioxide and so on. The worst polluters are trucks and buses. They need a lot of diesel. There is a cloud of black smoke coming out of the back when they step on the gas or start the engine. Aeroplanes need thousands of litres of fuel for one flight only. Factories need a lot of energy and they produce smoke and other dangerous substances. They have to build in filters, but they cost a lot of money. The filters must be changed or cleaned from time to time. If you heat your own house you produce also a lot af smoke and pollute the air. Solar energy is very clean, gas and wood are not so bad but coal is the dirtiest energy form. In the past all the ships were powered with coal.
b) water pollution
Sometimes there are tankeraccidents where the oil gets into the water and kills a lot of animals like fishes, seabirds, dolphins, seals, penguins, whales and so on. A lot of ships lead their waste and sewage into the water. Even smaller motorboats lose oil and pollute the water. Many towns - in Southern Europe and Third World countries- lead all their sewage into the Ocean because they have no money to build cleaning plants. Every summer millions of tourists use sunlotions and creams and when they go swimming the substances get into the water.
In Austria all the lakes have very clean water again because: all the lakes have cleaning plants and on many lakes motorboats are not allowed. There are high fines for offenders. In many places the groundwater is polluted by waste dumps or by pesticides and insecticides. The farmers use a lot of fertilizers in the Marchfeld and so you should not really drink the water there.
In Austria we have to collect waste and separate it in bins. Many people have a compost heap, it is for the kitchen waste, lawn cuttings and so on.
d) global warming
This is caused by the emission of carbon dioxide and other "greenhouse gases" into the air. It could result in climate changes with disastrous effects on vegetation, wildlife and human living conditions. Reports of droughts, floods and changing patterns of cultivation are increasing.