THE POLLUTION PROBLEMS

THE POLLUTION PROBLEMS
After studying this chapter, you will be able to:
1. Trace the history of pollution in the world.
2. Identify the major sources of worldwide pollution.
3. Distinguish between toxic pollutants and those that are harmful only to the environment.
4. Describe the main causes of air, water, and land pollution.
5. Enumerate the efforts exerted by some people to help reduce pollution.
4.1. MEANING OF POLLUTION
When there is a change in the physical, chemical, or biological condition in the environment which
harmfully affects the quality of life, including effects on other animals and plants, then we say that
there is pollution in environment.
The change is generally brought about by introduction of hazardous substance into the
environment. A hazardous substance includes any substance that poses a threat to human health or
to the environment. Substances that are poisonous to human beings and animals are called
toxicants. Those that harm to the environment may be corrosive, flammable, or explosive.
Examples of toxic materials are carbon monoxide (CO), sulfur dioxide (SO
2
), and the oxides of
lead and mercury.
Examples of substances that harm the environment include wastes disposed of improperly by
industries, nonbiodegradable materials, like plastic, thrown just anywhere; and excessive carbon
dioxide (CO
2
) introduced into the atmosphere.
Problems caused by hazardous substances are twofold: first, they cause a wide range of harmful
effects on human health such as cancer, damage to the brain, liver, kidney, bone marrow, embryo,
skin, gastrointestinal organs, and to the central nervous system; second, these substances can cause
long-term or permanent damages to ecosystem. For instance, toxic substances dumped into the
water system can cause long-term damage to most of our rivers and lakes.
We classify pollution into four types: air pollution, water pollution, land and soil pollution, and
noise pollution.

Guide questions
Name some hazardous substances emitted by vehicles that run on gasoline or diesel fuel. What
possible damage can they cause to humans?
4.2. AIR POLLUTION
Substances that pollute the air are generally of two types. The first types of air pollutants are those
that are directly harmful to humans. They include toxic materials emitted by factories and motor
vehicles. The second types of pollutants are those that damage the environment and possibly alter
the earth’s climate.
Figure 4.1: Environmental pollution
4.2.1. Toxic air pollutants
Toxic air pollutants include oxides of sulfur and nitrogen, carbon monoxide, volatile and organic
compounds, lead oxide, and benzene.
The main source of toxic pollutants is the burning of fossil fuels like gasoline, diesel, and
petroleum in power plants, factories, and motor vehicles. Burning of trash also produces toxic
pollutants.
Figure 4.2: Burning tyres harm to air environment
These pollutants are considered toxicants because the human body absorbs these gases together
with fine particles into the bloodstream, causing adverse health effects. The most obvious effects
are:
1. Breathing difficulties.
2. Increased susceptibility to respiratory infection.
3. Development of chronic lung disease.
4. Worsening of existing heart and lung diseases.
5. Fetal defects and various kinds of cancer.
Figure 4.3: Health effects by environmental pollutants
4.2.2. Contributors of common air pollutants
The urban and industrialized areas in the world are the greatest contributors of air pollution.
Knowing that pollutants are the causes of many bad effects on human health, these should be main
causes for alarm by the people in general and by the government in particular. As experienced by
the United States, Japan, and the European countries, emission control costs are high, but still,

control measures must be undertaken.
Otherwise, the cost of man-hours, health care, unproductively, and shorter life span will be more
staggering. UNEP and WHO suggested a gradual introduction, and proper maintenance of factories
and power plants.
Guide questions
1. Explain the two types of air pollution.
2. Is air pollution in your area serious? If it is, do you known if you or some of your neighbors
have suffered from of it? What suggestions can you give?
3. Do you know of some steps that the government has taken to reduce air pollution, especially
in the Ho Chi Minh City? How effective are they?
4. What are the forms of air pollution that can easily be avoided?
5. Enumerate some general effects of acid rain on the environment.
6. Explain the greenhouse effect.
7. Cite some possible consequences of an increase in global temperature.
4.3. LAND AND SOIL POLLUTION
There are two principal sources of wastes responsible for the land and soil pollution. The first one
is the solid waste which comes from mining operations. It includes direct waste from the mining of
minerals and fossil fuels and those associated with the mining and processing industries. Strip
mining not only produces mineral waste that pollutes the soil and streams but also leaves huge
scars on the land. The loosening of the soil leads to erosion during heavy rains, causing sediments
to settle at the bottom of rivers and lakes. Erosion also adds to the deterioration of the land, making
it unfit for agriculture. It also makes the water turbid-cloudy, thick, and dense.
Figure 4.4: Pollutants harm to the environment
Another type of solid waste is the by-products of agriculture. It includes animal manure and
wastes from slaughtered horses and from all forms of crop harvesting. These wastes are generally
less polluted because they are spread over wide areas. Also, they are biodegradable, meaning, they
return to the soil as nutrients of plants. In excessive amounts, they emit bad odor, which is almost
intolerable to human beings.
Guide question
1. What are the major sources of water pollution in Ho Chi Minh City? Do you know if

something is being done to reduce it?
2. Do you know of other rivers and lakes affected by soil erosion? Where does the eroded soil
come from?
4.4. RADIATION AND ITS HARMFUL EFFECTS
Radiation is the general term used to refer to a variety of rays to which life on earth is exposed to.
These include visible light, infrared and ultraviolet rays, X rays, cosmic rays, and rays from
radioactive materials.
In a wide sense, any result of radiation energy to a living organism is a biological effect of
radiation. This includes normal effects like photosynthesis on plants and vision in animals and also
the injurious effect burns, anemia, and cancer on humans and animals.
4.4.1. Historical background
When X rays were discovered by the German physicist Wilhelm Conrad Roentgen in 1895, the
focus of attention was its possible applications, especially in the field of medicine. The harmful
effects were observed one year later. In 1896, Elihu Thomas exposed one of his fingers to X rays
and observed the burns caused by these.
In the same year, the famous American inventor, Thomas Alva Edition, observed the effects of X
rays exposure on one of his assistants, Clarence Dally. Dally hair fell out and his scalp became
inflamed. Eight years later, he developed severe ulcers on both hands and arms. They became
cancerous and eventually caused his death.
The harmful effects of radioactivity were also observed by Pierre Curie, a French chemist and one
of the great scientists, in 1906. Burns were produced on the parts of the body exposed to radiation.
In 1925, a number of women exposed to paint containing radium became ill with anemia and had
lesions in the jawbone and mouth. Some of them developed bone cancer later.
Ernest Lawrence - an American physicist who invented the cyclotron, a rich source of neutron -
exposed rats to this deadly radiation. He found that fast neutrons are 21/2 times more effective in
killing them then slow neutrons.
Neutron radiation harmed and killed many people in Hiroshima, Japan, when an atomic bomb was
dropped there in 1945. A study was conducted on several hundred pregnant women who survived
the Hiroshima and Nagasaki bomb blasts. Their children were medically observed for more than 20
years. Many of them had heads smaller than the normal size, and there was a significant increase in

the number of mentally retarded children.
4.4.2. Specific harmful effects of radiation
There are many sources of radiation that may cause injury to human beings. The natural sources,
like cosmic rays and natural products like granite and monazite sands (an important source of the
element thorium), give dosage that are very safe to humans.
The artificial sources like medical X rays, high - voltage power supplies, television sets, and
luminous dial watches give significant dosage but the effects do not show until after many years.
These effects may include lower blood counts, temporary sterility, skin irritations, and on rare
occasions, cancer.
Figure 4.5: Harmful effect of radiation