Pollution is probably the most important problem in the world today.Unlike most of the other problems in the world, such as AIDS, pollution is a human creation.Now millions of chimneys, cars, buses, trucks all over the world exhaust fumes and harmful substances into the atmosphere. These poisoned substances pollute everything: air, land, water, birds and animals. So, it is usually hard to breathe in the large cities where there are lots of plants. Everything there is covered with soot and dirt. Big cities suffer from smog. Cars with their engine have become the main source of pollution in industrial countries.How can we protect ourselves from air pollution?Find realistic solutions to this problem.