LESSON NUMBER THREE

LESSON NUMBER THREE
Pollution has become a grave problem around the world. Some ecologists believe that if pollution continues at the present rate, the Earth may be made inhabitable to man.Pollution is usually at its highest level in large cities. The amount of industrial waste and the smoke from vehicles are creating very serious problems of health. When people breathe polluted air, minuteparticles often remain in their lungs. Scientists have found a connection between some pollutants and the formation of some lung diseases such as cancer and pneumonia.

Water pollution is also worryingthe humanity. It is often the result of deoxygenating which occurs when the oxygen in the water in not replaced. Many industries and chemical plants use water in their processes. In many cases thewater is returned dirtier and at a higher temperature. Warm water holds less oxygen than cold water and this can force out the existing plant and fish life. Water pollution can also result fromaccidents such as spills of oil or chemicals from ocean tankers.

In many countries different steps have been taken because of the pollution. Important laws have been passed making it necessary for vehiclesto have smog control devices. However, these devices are not enough to control all the waste. Many agencies have been set up by different governments to study this problem. They are trying to predictthe effect of the pollution on our environment. These agencies aim to clear up some of the pollution that already exists. They are also planning to prevent future pollution.



NÚMERO DE LECCIÓN TRESLa contaminación se ha convertido en un grave problema en todo el mundo. Algunos ecologistas creen que si la contaminación continúa al ritmo actual, la Tierra puede hacer inhabitable para el hombre.La contaminación es por lo general en su nivel más alto en las grandes ciudades. La cantidad de residuos industriales y el humo de los vehículos están creando serios problemas de salud. Cuando la...