Chapter 8 – Pollution
1. Following are some statements about pollution. Which type of pollution do those express?
a. Fog seems to be appearing in Delhi during day hours.
Ans: Air pollution.
b. Many times, vomiting and dysentery occurs after eating ‘pani puri’.
Ans: Water pollution.
c. Problem of sneezing occurs sometimes during visit to garden.
Ans: Air pollution.
d. Crop does not grow up in some areas.
Ans: Soil pollution.
e. People living in the busy squares face the problems like short breathing and other respiratory problems.
Ans: Air pollution.
2. Read the passage and identify the sentences expressing types of pollution.
Nilesh is a student of std. VIII and lives in an urban area. It takes about an hour to go to the school by bus. He faces the heavy traffic of two wheelers, four wheelers, rickshaws, buses while going to school. He has been facing the problem of asthma since the last few days. Doctors recommended him to stay away from urban areas. Since then, his mother sent him to the village of his maternal uncle. Nilesh saw the heaps of garbage at many places in the village. Foul smell of human and animal wastes was present at many places. Blackish water with a foul smell was flowing in a stream. He developed some abdominal disease within a few days.
Ans: The sentences expressing various types of pollution are as follows:
(i) He faces the heavy traffic of two wheelers, four wheelers, rickshaws, buses while going to school: Air pollution
(ii) He is facing the problem of asthma since last few days: Air pollution
(iii) Nilesh saw the heaps of garbage at many places in village: Soil pollution
(iv) Foul smell of human and animal waste was present at many places: Air pollution
(v) Blackish water with foul smell was flowing in a stream: Water pollution
(vi) He developed some abdominal disease within few days: Water pollution
3. Match the pairs from ‘A’ and ‘B’ columns and explain the effect of pollution on human health.
| Column ‘A’ | Column ‘B’ |
|---|---|
1. Water containing cobalt | a. Mental retardedness |
2. Methane gas | b. Paralysis. |
3. Water containing lead | c. Inflammation of lungs. |
4. Sulphur dioxide | d. Skin cancer |
5. Nitrogen dioxide | e. Irritation of eyes |
Ans:
| Column ‘A’ | Column ‘B’ |
|---|---|
1. Water containing cobalt | b. Paralysis. |
2. Methane gas | d. Skin cancer |
3. Water containing lead | a. Mental retardedness |
4. Sulphur dioxide | e. Irritation of eyes |
5. Nitrogen dioxide | c. Inflammation of lungs. |
Ans: Pollution has significant and widespread effects on human health, impacting various organ systems and overall well-being. Different types of pollution, such as air, water, soil, and noise pollution, can lead to a range of health issues:
(1) Air Pollution:
(i) Respiratory Issues: Inhalation of polluted air containing substances like particulate matter (PM), ozone (O₃), sulfur dioxide (SO₂), nitrogen oxide (NO), and volatile organic compounds can cause or respiratory conditions such as asthma, chronic obstructive pulmonary disease (COPD), and bronchitis.
(ii) Cardiovascular Problems: Air pollution has been linked to an increased risk of heart attacks, strokes, and other cardiovascular diseases due to the inflammation it triggers and its effect on blood vessels.
(2) Water Pollution:
(i) Waterborne Diseases: Contaminated water sources can lead to the spread of waterborne diseases such as cholera, dysentery, and gastrointestinal infections, primarily caused by bacteria, viruses, and parasites.
(ii) Toxic Chemical Exposure: Polluted water containing heavy metals, pesticides, and industrial chemicals can lead to chronic health issues, including neurological disorders, cancer, and organ damage.
(3) Soil Pollution:
Food Contamination: Crops and plants grown in polluted soil can absorb toxins and contaminants, entering the food chain and potentially causing health issues for humans who consume these contaminated foods.
4. True or false
a. Water does not get polluted by washing the clothes in running water of river.
Ans: Wrong
Correct statement: Water gets polluted by detergents and other chemicals while washing clothes in the running water of the river.
b. More the use of electric appliances, more will be the pollution.
Ans: True
5. Answer the following.
a. What is pollution?
Ans: Pollution is defined as the contamination of the natural environment in such a way that it will be harmful to the ecosystem. There are many types of pollution, such as soil pollution, air pollution, water pollution, etc.
b. What are pollutants?
Ans: Pollutants are factors that adversely affect the natural functions of the ecosystem and cause harmful effects on the abiotic and biotic factors of the ecosystem.
For example – nitrogen oxides, sulphur oxides, carbon monoxide, pesticides, etc.
c. What is acid rain?
Ans: Rain containing high levels of acids like sulphuric acid and nitric acid, formed due to the mixing of oxides of sulphur and nitrogen with rainwater or snow is known as acid rain.
d. What is green house effect?
Ans: Greenhouse effect is the phenomenon in which infrared radiations reflected from the Earth’s surface are trapped by greenhouse gases present in the atmosphere, thus making the Earth warm.
e. Which are visible pollutants known to you?
Ans:
(i) The polluting substances that are easily seen with the naked eye can be called visible pollutants.
(ii) For example; solid waste, plastic articles, plastic bags, suspended things in the water, metal refuse, etc.
f. Which are invisible pollutants?
Ans:
(i) The pollutants, which are completely dissolved in water or mixed in the air, cannot be seen, and hence they can be called invisible pollutants.
(ii) For example; the insecticides spread on the crops, aerosols, many hazardous gases in the air, toxic compounds that are totally soluble in water, etc.
6. Answer the following
a. Give two examples of each of water, soil and air pollution from your residential area.
Ans:
(i) Water pollution:
(a) Effluent from small-scale industries directly released into water bodies changes its chemical properties and colour.
(b) Dumping garbage into streams results in pollution by plastic, waste food, etc.
(ii) Soil pollution:
(a) Landfilling or improper dumping (illegal dumping) of domestic garbage leads to soil pollution.
(b) Leakage of sewer pipelines or sewage tanks pollutes soil.
(iii) Air pollution:
(a) Heavy vehicular traffic causes the release of pollutants into the air.
(b) The burning of waste contaminates the air with particulate matter, fly ash, and other toxic pollutants.
b. How does the pollution occur due to vehicles? Give the names of vehicles causing least pollution.
Ans:
(i) Vehicles, or automobiles, have been regarded as the greatest sources of air pollution.
(ii) They release pollutants such as carbon monoxide, hydrocarbons, nitrogen oxides, etc.
(iii) Apart from these gases, automobile exhaust also contains gaseous lead and particulate matter.
(iv) 2-stroke engines, poor fuel quality, old vehicles, vehicles that are PUC disqualified, inadequate maintenance of vehicles, and congested traffic are also reasons that increase vehicular air pollution.
(v) Vehicles that cause the least pollution are bicycles, solar cars, electric cars and trucks, plug-in hybrid electric vehicles, hydrogen fuel cell vehicles, cleaner-burning gasoline vehicles, vehicles using CNG instead of petrol, vehicles having four-stroke engines, etc.
c. What are natural reasons for water pollution?
Ans: The various natural causes of water pollution are as follows:
(i) Growth of aquatic weeds leads to the depletion of O₂ levels in water and deteriorates its natural quality.
(ii) Decomposition of organic matter present in water like dead plants and animals, etc. can lead to depletion of O₂ levels in water.
(iii) Deposition of mud or sludge can cause a diversion or change in the course of rivers thus affecting the biodiversity in that water body.
(iv) Soil erosion adds numerous biotic and abiotic factors in water. This increases turbidity of water bodies and also disrupts the normal composition of the water body.
(v) Microbes like fungi and bacteria require oxygen for oxidation of decaying organic matter in water, hence reducing dissolved O₂ levels.
(vi) Excessive algal growth occurs due to water pollution by organic and inorganic matters. This in turn may disturb the natural water ecosystem.
(vii) Nematodes present in soil may enter water along with rainwater. Some nematodes may be parasitic and are harmful to human beings.
d. Suggest four preventive measures for air pollution.
Ans: Preventive measures for air pollution are as follows:
(i) Installation of pollution control machinery in factories to control the release of smoke containing harmful particles, for example, an arrester (used to separate particulate matter from contaminated air), a filter, etc.
(ii) Sewage and other waste generated in cities with foul odours should be disposed off properly.
(iii) Proper control and regulations should be established for atomic tests and the testing of chemical weapons.
(iv) There should be control or a ban imposed over products that can release harmful CFC’s into the atmosphere.
e. Explain relation between green house effect and global warming.
Ans:
(i) Greenhouse gases like CO₂ play an important role in absorption of solar heat in the Earth’s atmosphere. The effect of these gases on the Earth is known as the greenhouse effect.
(ii) Due to an increase in the concentration of greenhouse gases in the atmosphere, the heat trapped in the atmosphere causes a gradual increase in the global temperature, a phenomenon known as global warming. Thus, greenhouse effect is related to global warming
f. Construct two slogans each on air, water and soil pollution.
Ans:
Air Pollution:
1. “Breathe Easy, Act Now: Clear Skies, Healthy Lives!”
2. “Clean Air, Bright Future: Uniting for Pollution-Free Horizons!”
Water Pollution:
1. “Guardians of the Waves: Rise Against Water Pollution!”
2. “Pure Waters, Stronger Communities: Stop Pollution at the Source!”
Soil Pollution:
1. “From Ground Up: Heal Soil, Sustain Life!”
2. “Rooted in Responsibility: Preserving Soil for Generations to Come!”
7. Classify the following pollutants into natural and manmade categories.
Sewage, dust, pollen grains, chemical fertilizers, vehicular smoke, algae, pesticides, waste of animals and birds.
Ans:
| Natural pollutants | Manmade pollutants |
|---|---|
Dust, pollen grains, algae, waste of animals and birds | Sewage,
chemical fertilizers,
vehicular smoke,
pesticides, |