NIOS Environmental Science (333) Notes/Answer| Chapter-5|Environmental Pollution

NIOS Environmental Science (333) Notes/Answer| Chapter-5|Environmental Pollution. Important questions for NIOS Environmental Science (333) Questions Answers brings you latest queries and solutions with accordance to the most recent pointers SOS . Students will clear all their doubts with regard to every chapter by active these necessary chapter queries and elaborate explanations that area unit provided by our specialists so as to assist you higher. These queries can facilitate students prepare well for the exams thanks to time constraint . NIOS Environmental Science (333) Notes/Answer| Chapter-5|Environmental Pollution

HS 2nd years Solutions (English Medium)

NIOS Environmental Science (333) Notes/Answer| Chapter-5|Environmental Pollution


1. What do you mean by environmental pollution? Name the different types of pollution. 

Ans: The word pollution derived from the Latin word pollutionem (meaning to make dirty) is the unfavourable alteration of our environment largely because of the anthropogenic or human activities. More precisely, pollution is an undesirable change in physical, chemical and biological characteristics of air, water and soil that may harmfully affect man, animal, other living organisms or property. 

Different types of pollution:

  1.  According to environment – When different segments of the environment are affected by pollution, they may be categorized as 
  1. Air pollution 
  2. Water pollution 
  3. Soil pollution 

(ii) According to pollutant – Pollution caused by pollutants may be of different types such as

  1.  Thermal pollution 
  2.  Noise pollution 
  3.  Radioactive pollution 
  4.  Solid waste pollution 
  5.  Oil pollution 
  6.  Industrial pollution 
  7.  Marine pollution

2. What is air pollution? Identify the sources of air pollution.

Ans: Air pollution may be defined as the presence of one or more pollutants/contaminants like dust, smoke, mist, odour, suspendn hijacked particulate matter (SPM) etc. in the atmosphere which are injurious to human being, plants and other animals or which unreasonably obstruct the comfortable enjoyment of life and property. 

Air pollution may be described as “the imbalance in quality of air so as to cause adverse effects on the living organisms existing on earth” 

The presence of one or more contaminants in the atmosphere in such quantity and for such duration as is injurious or tends to be injurious to human health or welfare, affect other animal or plant life may be called air pollution. 

Sources of air pollution: 

Air is never found absolutely clean in nature. Pollution of air started from the very moment when the primitive men knew how to make fire. 

Major sources of air pollution can be of two types 

(i) Natural sources

  1.  Volcanic eruption: releasing poisonous gases like S0,, H,S, CO etc.
  2. Forest fires: In the areas of tropical region throughout the year forest fire is a common feature. Very large quantities of smoke and particulate matter are liberated during their breakout. 
  3. Decomposition of organic and inorganic substances: Methane gas, carbon dioxide are released into the air. 
  4. Dust: Dust is always present in the atmosphere in varying amounts.
  5. Pollen grains of flowers: The pollution is also caused by the production of pollen in the spring season. Pollens or aeroallergens enter the atmosphere from weeds, grasses and trees. They are mainly responsible for causing allergy. 
  6. Fungal spores: Micro-organisms such as algae, fungi, bacteria, yeasts, rusts, spores etc are present as variable particles in the atmosphere.
  7. Radioactive materials: The radioactive minerals present in the earth crust and action of cosmic rays from outer space on gaseous constituents of the atmosphere are mainly responsible for radioactivity of the atmosphere

In the lower atmosphere the natural chemical reactions lead to the conversion of gases or vapours into solid and liquid products by oxidation, reduction, combination, combustion, condensation or polymerization processes etc. In the upper atmosphere the photochemical reactions may undergo breakdown to the more complex molecules by absorption of high energy UV solar radiation.

(ii) Man-made sources

  1.  Deforestation
  2. Burning of fossil fuels
  3. Emission from vehicles
  4. Rapid industrialization
  5. Modem agricultural practices

3. Mention few effects of air pollution on human health.


Air pollutantsSources of productionEffects on man
1Sulphur-dioxideCoal & oll combustionCauses chest constriction, headache, vomiting, death from respiratory ailments
2Nitrogen oxidesSoft coal & automobile exhausts, unvented gas stove, kerosene heaters, wood stovesHeadache, drowsiness, irritated lungs, childrens colds Inhibits cilia action so that soot and dust penetrate far into the lungs
3Carbon monoxideBurning of coal, gasoline, motor exhausts, faulty furnaces, unvented gas stove, kerosene heaters, wood burningCauses nausea, reduces oxygen carrying capacity of blood, Headache, drowsiness, irregular heartbeat
4SPM ash, soil smoke etc.Incinerators & every manufacturing processesCauses eye irritation, emphysema, cancer
5Hydrogen sulphidaRefineries, chemical, industrial, bituminous fuelsCauses irritation of eyes and throat
6AmmoniaExplosives, dye making, fertilizer plantsInflamas upper respiratory pxixayca
7Phoagana carbonyl chlorideChemical and dye makingInlove coughing irritation and fatal pulmonary edema
8AldehydeThermal decomposition of oils, fats or glycerolIrritate nasal and respiratory tracts
9SuspendedParticlesIncinerators and almost every manufacturing processCause amphysema, eye irritation, cancer
10AchaninsPipe insulation, vinyl ceiling floor tilusLung diseases, lung cancer

4. What is water pollution? What are the effects of water pollution on human health? 

Ans: Water pollution may be defined in a number of ways

  • Alteration in physical, chemical and biological characteristics of water that may cause harmful effects on man and other aquatic biota.
  • Addition of excess undesirable substances to water that make it harmful to man, animal and aquatic life or otherwise cause significant departure from the normal activities of various living organisms in or around water.

Problems associated with drinking water: Man needs water for drinking, cooking, washing, bathing, gardening, irrigation, industry and for a lot of other purposes. The quality of water used by man for various purposes varies widely and what is satisfactory for one purpose may not be so for another. Water for human consumption must be free from pathogenic microorganisms and other substances which are hazardous to health. A water sample is normally rejected for drinking purposes if it is highly turbid, highly coloured or has an objectionable taste, but the absence of these adverse sensory effects does not guarantee the safety of water for drinking. The enormous pressure exerted by rapidly increasing population, massive industrial activities, and modern agricultural practices have resulted in discharge of a very large amount of pollutants to the water bodies. The problem is particularly manifested as the fresh water suitable for drinking purposes is in very short supply.

Contamination of drinking water, either directly or indirectly by sewage and other wastes or by human or animal excrement is the most common and widespread danger associated with water quality problem particularly in the underdeveloped world. Faecal pollution leads to introduction of a variety of intestinal pathogens, bacteria, virus and parasites causing diseases starting from mild gastroenteritis to severe and fatal dysentery, cholera or typhoid. When drinking water is contaminated with sewage, gastroenteritis and infectious hepatitis may occur in epidemic proportions. Other diseases like rashes, fever, myocarditis, meningitis, respiratory diseases etc. are also likely. Protozoic diseases like amoebiasis, giardiasis may also occur through sewage contamination of water sources.

The chemical contamination does not cause immediate, acute health problems unless they are present in massive quantities through some accident. However, these are important in this respect that after prolonged periods of exposure to them, they can do considerable harm by being cumulative poison and carcinogens.

It is generally thought that undesirable constituents in water will affect the appearance, smell or the taste of the water and a person can evaluate the acceptability of the water sample with his senses. This is no longer true. No water sample can be termed as safe if it is not subjected to rigorous tests. Such tests particularly for drinking water are still in the infant stage in Assam.

Access to safe drinking water is vital for healthy life, also basic human rights and accordingly considered as a component of all holistic plans throughout the globe for health protection. The importance of water, sanitation and hygiene for health and development has been reflected in the outcomes of a series of international policy forums and environment related protocols.

Water contamination: The most common and widespread health risk associated with drinking water is microbial contamination, the consequences of which mean that its control must always be of paramount importance, because microbial contamination of major urban systems has the potential to cause large outbreaks of water borne diseases. Discharge of untreated sewage and agricultural waste waters, effluents from the industries, dumping of solid wastes, oil spills from giant oil tankers, mining etc. are responsible for the contamination of the drinking water sources.

Water borne diseases: Diseases caused by ingestion of water contaminated by human activities or animal excreta, which contain pathogenic microorganisms. Contaminated surface water sources and poorly maintained municipal water distribution systems contribute to transmission of water borne bacterial diseases. Brewery, dairy and distillery organic load, dyeing, leather taming, textile colour, organic load, heavy metals etc. can also affect water quality. Common water borne diseases

  1. Typhoid – Salmonella typhi 
  2. Cholera – Vibrio cholerae
  3. Dysentrry – shigella
  4. Diarrhoea – cryptosporidium
  5. Giardiasis – Giardia lamblia 
  6. Diarrhoea – E coli
  7. Gastroenteritis – viruses
  8. Polio-polioviruses

NIOS Class 12th Environmental Science (333) Notes/Question Answer

ChaptersChapters NameLink
Chapter 1Basic Concept of EnvironmentClick Here
Chapter 2Ecological ConceptClick Here
Chapter 3Biodiversity and its conservationClick Here
Chapter 4Natural ResourcesClick Here
Chapter 5Environmental PollutionClick Here
Chapter 6Social Issues and EnvironmentClick Here
Chapter 8 (A)Disaster Management: Responsibilities and PrecautionsClick Here
Chapter 8 (B)Road SafetyClick Here

5. What is soil pollution? How can it be controlled ? 

Ans: Soil is the upper most part of the earth crust and is a mixture of organic as well as weathered rock and materials necessary for the plant growth. Soil system is indeed very complex and dynamic. It is formed as a result of long term process of complex interactions, disintegration and decomposition of rocks due to weathering leading to the production of mineral matrix in close association with interstitial organic matter. Dumping of various types of specially domestic and industrial wastes, application of pesticides in the agricultural fields etc. make the soil polluted. Even the fertility of soil decreases due to addition of a number of different types of toxic materials.

  1.  Industrial effluents should be properly treated before discharging them on the soil.
  2. Solid wastes should be properly segregated as biodegradable and non-biodegradable wastes at source and then disposed-off by adopting effective scientific methods.
  3. Use of bio-fertilizers should be encouraged instead of chemical fertilizers.
  4. Application of pesticides should be controlled.
  5. Bioremediation can be adopted for degradation of toxic chemicals present in soil. 
  6. Necessary enactment of laws should be made for panel action against those who are involved in polluting soil.
  7. Awareness should be created among the people. 

6. What are solid wastes ? How are they classified? Give examples.

Ans: Solid wastes are all the wastes produced by household, commercial, institutional, agricultural, mining and industrial activities and are discarded as useless or unwanted. An apt definition of solid waste is “materials in the wrong place”, implying that a material becomes waste only when a specific owner ceases to have a use for it. With rapid urbanization, industrialization, population growth and increasing economic standard, the solid waste has become a serious threat in recent years and the situation is going to be worse in coming years if appropriate measures are not taken immediately. Dumping the wastes as a waste has two-fold negative implications. On the one hand, it pollutes the air, water and land resulting in diseases and destruction of human habitat, while on the other hand, it deprives us of a powerful resource material for producing energy, electricity, manure etc. A commercially viable technology suited to deal with the content of the waste material can put this double-edged weapon in the service of human race and natural habitat.

7. Discuss the environmental effects of solid wastes.

Ans: Solid waste has the potential to degrade the air, water and the soil. There are potential risks to health and to the environment from improper handling of solid wastes. Direct risks concern mainly the workers in the field, who need to be protected, as far as possible, from skin contact with the waste. There are also specific risks in handling wastes from hospitals and clinics.

For the general public, the main risks to health are indirect and arise from the breeding of disease vectors, primarily flies and rats. Improper storage and disposal provide the condition under which these risks arise. It also helps in inducing health hazards like plague, dengue, cholera etc. Garbage burning contributes significantly to urban air pollution. Using water polluted by solid waste for bathing, irrigation and drinking can also cause diseases like skin infections.

The other environmental damage caused by solid wastes is aesthetic ugliness of street litter and the destruction of the beauty of the countryside by uncontrolled dumping of city wastes. More serious and often unrecognized is the transfer of pollution to water bodies which occurs when the leachate from a refuse dump enters surface water or ground water. Air pollution may be caused from the inefficient burning of waste. Industrialization introduces the dangers of hazardous wastes. Improper disposal of such wastes results in the death of humans and other animals. 

The present practice of solid waste disposal in different cities and towns is highly unscientific and poses a lot of environmental problems such as

  • open dumps are malodorous places in which disease carrying vermins such as rats and flies proliferate 
  • methane gas is released into the surrounding air due to decomposition of solid wastes by the micro-organisms.
  • a liquid that oozes and seeps through a solid waste heap ultimately finds its way into the soil, surface water and ground water.
  • hazardous materials dissolved in this liquid contaminate underground water and soil strata 
  • the solid waste is highly heterogeneous and is not being segregated at any stage. It includes wastes from industries, hospitals and nursing homes, domestic waste etc.
  • the leachate consisting of a variety of chemical constituents seeps and pollutes the ground water. 
  • absence of landfill liners aggravate the problem furthermore. 
  • health hazards faced by the residents living in the nearby areas of dumping sites cannot be ignored.
  • the present practice of collecting solid waste from the individual houses results in wastage of time and thereby increases the cost of collection.
  • transportation of collected solid wastes openly by the tractors or trucks is unhygienic and the aesthetic look of the city is also affected. 

8. Mention two methods of solid waste management.

Ans: The problem of solid waste management encompasses both the urban and rural spheres. This malaise needs to be looked into and considered urgently, lest it should become an uncontrolled proportion in the near future, threatening the generations to come. The day-today management of municipal solid waste is a complex and a costly task. Direct activities that must be considered and coordinated on a daily basis include the rates, collection, storage, transfer and transport, processing and disposal of wastes. These activities are associated directly with the management programme which include financing, operations, equipment and personnel, cost involved and budgeting, contact administration, ordinates and guidelines, public communications and public awareness. In short, the solid waste management imbibe in itself the 

  1.  effective refuse of the solid wastes
  2. determining a substitute technology toward recycling of solid wastes, with due consideration given to the economic constraints and environmental aspects.

9. What is noise pollution? Write two probable effects of it on human health.

Ans: We hear various types of sounds every day. Crowded cities, various means of transportation systems, new mechanisms of recreation and entertainment etc. are dumping different types of sounds to the environment and people have to talk about the ill affects of these sounds. A particular sound may be musical to one but noise for another. A sound may be pleasant when soft, but noise when loud.

So noise pollution has become an important matter of concern specially in the urban environment. Noise pollution may be defined in a number of ways – 

Any unwanted electromagnetic signal that produces a displeasing effect and which interferes with human communication, comfort and health is termed as noise pollution. 

Noise pollution is the unwanted sound dumped into the environment without regard to the adverse effect it may have. 

The effects of noise pollution may be auditory effects or non-auditory effects.

a) Auditory effects:

The most acute and immediate effect of noise pollution is the impairing of hearing which may cause auditory fatigue and finally lead to deafness.

b) Non-auditory effects: 

The non-auditory effects are also equally serious. It includes interference with speech communication, annoyance leading to ill temper, mental anxieties, mental stress, bickering and violent behaviour. Noise pollution affects human health, disrupts comforts and working efficiency. Excessive noise pollution causes psychological disorders.

10. What measures can be taken to keep drinking water sources clean and safe?

Ans: The following suggestions can be made to improve the quality of drinking water at the community as well as at the individual level. Since cost is less, these are quite acceptable even to families with lower income.

  1. Common filtration processes using sand, stone and charcoal should be carried out as the first treatment. 
  2. High turbidity and iron can be removed by alum treatment and improved filtration technique at least in the rainy season. 
  3. Hardness can be softened by boiling. This process also kills bacteria. 
  4. Disinfection with chlorine should be done to minimize bacteriological contamination.
  5. Defluorination technique using low cost bio absorbent can be encouraged.
  6. Boiling of drinking water is highly essential.

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