*What are some sources of pollution--something that makes air, water, or the ground dirty or dangerous in Bangladesh?
*What problems do they cause?
Pollution is a change in the physical, chemical, or biological conditions in the environment (land, water, and air) that affects the quality of life for people, animals, or plants. It makes air, water, and the ground dirty and dangerous. Though we think of pollution as being a modern problem, it actually dates back many centuries. In the Middle Ages, Europeans began living together in relatively large cities. These cities were often dirty places with unsafe water, where disease spread rapidly. Although much has been done to improve sanitation, pollution problems have become more serious since the Industrial Revolution. Changes from agricultural to industrial economies caused changes that have resulted in air, water, and ground pollution. Even in less industrialized counties, there are pollution problems.
Smoke from factories and exhaust gasses from cars cause air pollution. This has many serious consequences. Smog is harmful to human health, especially for people who already have lung problems. Chemicals from this air pollution can also combine with moisture to form acid. This eats away at stone and brick buildings. In places like Rome, it has done serious damage to ancient stone buildings, arches, and statues. It may also fall in the form of acid rain, often hundreds of miles away from the source of the air pollution. Acid rain increases the acidity of the soil, ponds, and lakes. This can damage or kill wild animals and plants and pollute drinking water.
Another consequence of air pollution is the possibility of global warming. As carbon dioxide from the burning of various fuels builds up around the earth, the sun's warmth is held in close to the earth. This is called the "greenhouse effect." If it continues, the average temperature could rise by up to 9 degrees Fahrenheit in the next fifty years. This could change weather patterns, causing droughts in some places and flooding in others.
Various chemicals also cause pollution. Insecticides used by farmers to protect their crops from insects can also affect other animals. DDT is a well-known case. It is an insecticide that builds up in the tissues of animals that eat it, harming or killing the animals that, in turn, eat them. DDT is no longer used in most rich countries, but some companies still sell it to poorer countries where its dangers are not so well known.
Sometimes manufacturing involves harmful chemicals, and these must be disposed of. If they are not disposed of properly and sometimes even if they are, they may pollute the ground or water. Cancer-causing chemicals buried in the ground have been known to leak out, affecting the people who live above them.
Refuse disposal has also become a serious problem. As new goods are obtained, old ones are thrown away, along with often unnecessary packaging. Millions of tons of rubbish are disposed of every year. It takes a great deal of space, and, in some cases, there is no more room. When it is burned, it pollutes the air. If it is disposed of in rivers and seas, it causes water pollution. Plastics in particular are a disposal problem. Though wood and paper break down easily through the action of bacteria, plastics require a very long time.
Water pollution also comes from a variety of sources. The disposal of domestic sewage, sometimes untreated or inadequately treated, into bodies of water contributes to pollution. Breaking down the waste requires bacteria, which use up oxygen in the water that is needed by fish.
Fertilizers used by farmers help produce more food, but they can also cause many problems. They can be washed into rivers and make algae grow so quickly that oxygen in the water is used up. This causes other plants and animals to die.
The use of nuclear energy has increased in recent decades and with it the risk of radioactive pollution. The risk comes mainly from two sources; accidents at nuclear plants and nuclear waste disposal. Nuclear power plants produce waste that takes many centuries to become safe. The problem of disposing of this waste is very serious. Now the waste is put in concrete and buried at sea, but this cannot go on forever.
Pollution is a problem with a long history. However, it is a greater danger today than it has ever been. We have more potential to do permanent damage to the environment, to plant and animal life, and to ourselves, than ever before.
c. Write short answers to the following questions:
1. What were European cities like during the Middle Ages?
2. What has resulted from the change from agricultural to industrialized economies?
3. Where does the acid come from that eats away at stone and brick?
4. What problem does acid rain cause?
5. What causes global warming?
6. What could be the effect of an increase in temperature?
7. What is the problem with insecticides?
8. What can happen when harmful chemicals are disposed of?
9. What are the problems with refuse disposal?
10. What are three sources of water pollution?
11. What are the two sources of radioactive pollution?
12. Why is pollution a greater danger today than in the past?
*What are some sources of pollution in your local area?
*What problems do they cause?
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