Fossil Fuels
In addition to increasing the levels of greenhouse gases, the use of fossil fuels causes other negative repercussions for the environment such as smog. Smog is a mixture of smoke and fog and it is composed of substances resulting from the interaction of sunlight and the smoke produced by the combustion of coal and oil derivatives. It tends to form in urban areas where the air is stagnant and cannot disperse naturally; it causes irritation to the eyes and to the respiratory tract, and it can be carcinogenic. In mixing with water vapour, it penetrates clouds and can cause acid rain which destroys plants and aquatic ecosystems, its acidity capable of slowly corroding buildings and monuments.
There have been serious events caused by this phenomenon, one being the Great Smog, an environmental catastrophe which struck London in December 1952, when, during a spell of extremely cold weather, Londoners added more coal, with a high sulphur content, to their furnaces: the combustion fumes formed a thick layer of smog all over the city.
This dense and smelly fog enveloped the city for five days, causing the death of some 12,000 people and 100,000 cases of disease. It was so thick that people had to walk close to the walls and schools were closed for fear the children would get lost. It even penetrated the buildings: theatrical performances and the projection of films were suspended because the people in the audience could not even see the stage or screen.
This event shook the world and led to the birth of a new modern environmental awareness: in Great Britain, in 1956, the Clean Air Act was approved, the first important environmental law passed on this planet. Since then, the situation has changed greatly. But not everywhere: in some countries, like China, which has 16 of the 20 most polluted cities in the world, events of atmospheric pollution similar to those of the Great Smog still occur today.
