- On human health: Air pollution causes respiratory diseases like asthma, bronchitis, lung cancer, heart problems, eye irritation, and nervous system damage due to gases and fine particulates.
- On animals: Polluted air contaminates forage and water, leading to chronic poisoning, fluorosis, and other diseases in domestic and wild animals.
- On plants: Air pollutants damage leaves, reduce photosynthesis, cause chlorosis, necrosis, reduced crop yield, and inhibit growth; lichens act as pollution indicators.
- On materials: Pollutants cause corrosion of metals, erosion of buildings and monuments, fading of textiles, and damage to rubber and paints (e.g., Taj Mahal damage).
- On atmosphere and climate: Air pollution leads to greenhouse effect, global warming, acid rain, ozone layer depletion, reduced visibility, and long-term climate change.
Definitions [29]
Definition: Environmental Pollution
Any undesirable change or imbalance in the physical, chemical, or biological components of the environment that harms life is called environmental pollution.
Define environmental chemistry.
Environmental chemistry is the study of chemical and biochemical processes occurring in nature. It deals with the study of origin, transport, reaction, effects, and fates of various chemical species in the environment.
Definition: Pollutant
Any substance which causes pollution is called a pollutant.
Definition: Air Pollution
Air pollution means degradation of the air quality which harmfully affects the living organisms as well as certain objects.
or
Contamination of air by harmful substances like poisonous gases, smoke, particulate matter, microbes, etc., is called air pollution.
Definition: Greenhouse Effect
The natural phenomenon by which certain atmospheric gases trap heat and warm the Earth’s surface is called the greenhouse effect.
Define global warming.
The gradual increase in Earth’s average surface temperature due to rising concentrations of greenhouse gases in the atmosphere is called global warming.
Definition: Global Warming
The gradual increase in the average surface temperature of the Earth due to rising concentrations of greenhouse gases in the atmosphere is called global warming.
Define the following
Greenhouse effect
The warming up of the atmosphere due to trapping of the solar radiation reflected by the earth by gases like carbon dioxide is called Greenhouse effect.
Definition: El Nino Effect
The global impact on climate and weather caused by the eastward movement of warm Pacific waters and changes in atmospheric pressure is called the El Nino effect.
Definition: Water pollution
Water pollution means any change in the water quality which makes it unsuitable for use by humans and by other living organisms.
Define the following term:
Oil spills
Oil spills are the accidental discharges of petroleum into oceans or estuaries. The sources of spills are overturned oil tankers, offshore oil mining, and oil refineries.
Define the following.
Specific heat capacity
The amount of heat that is needed to raise the temperature of a unit mass of a substance by 1°C is called specific heat capacity.
Definition: Eutrophication
The natural process of aging of a lake due to gradual enrichment of its water with nutrients, leading to increased biological productivity, is called eutrophication.
Definition: Biochemical Oxygen Demand (BOD)
The amount of dissolved oxygen required by bacteria and other microorganisms to decompose and stabilise organic matter present in wastewater is called Biochemical Oxygen Demand (BOD).
Definition: Biomagnification
The progressive increase in the concentration of toxic substances at successive higher trophic levels of a food chain is called biomagnification.
Definition: Bioconcentration
The process by which substances present in very low or insignificant amounts in the environment enter and concentrate within organisms through food chains is called bioconcentration.
Definition: Bioaccumulation
The accumulation of pesticides or other toxic substances within the body of living organisms over time is called bioaccumulation.
Definition: Ecological sanitation (Ecosan)
A sustainable system of human waste management that safely recycles human excreta without using water is called ecological sanitation (Ecosan).
Definition: Noise Pollution
Noise is defined as any unpleasant/loud undesired sound interfering with one's hearing and concentration and the pollution caused due to noise is termed as noise pollution.
Define the following term:
Noise
Noise is defined as any unpleasant, loud, undesired sound that interferes with one’s hearing and concentration, and the pollution caused by noise is termed noise pollution.
Define ‘Noise Pollution’.
Noise pollution, also known as sound pollution, is defined as the presence of excessive, unwanted, or harmful sounds in the environment that disrupt normal activities and adversely affect the health and well-being of humans and other living organisms.
Definition: Decibel (dB)
The basic unit used to measure the loudness or intensity of sound is called decibel (dB).
Definition: Radioactive pollution
The increase in natural background radiation due to human activities involving the use of naturally occurring or artificially produced radioactive materials is called radioactive pollution.
Define the following term:
Pesticides
Pesticides such as DDT (dichloro-diphenyl-trichloroethane) are used in agriculture to destroy pests, alter the basic structure of the soil, kill microorganisms in it, and may even reach the human body through food grown in such soils.
Define the following term:
Sanitary landfills
Sanitary landfills are places where waste is dumped in a ground depression and covered with dirt every day.
Definition: Soil Pollution
The contamination of soil by natural or synthetic substances that adversely affect its physical, chemical, and biological properties and reduce its productivity is called soil pollution.
Definition: Soil Erosion
The loss of soil or disturbance of the soil structure is called soil erosion.
Definition: E-Wastes Management
Irreparable computers and other electronic goods are known as electronic wastes (e-wastes).
Definition: Deforestation
Deforestation is the conversion of forested areas into non-forested areas for agricultural, industrial, urban or other human uses.
Key Points
Key Points: Air Pollution
- Air pollutants are of two types - particulate (smoke, smog, dust, heavy metals) and gaseous (CO₂, CO, SO₂, NO, NO₂). PM2.5 particles cause the greatest harm, penetrating deep into the lungs, causing irritation and breathing disorders.
- NO₂ + water vapour = nitric acid, causing irritation to eyes, lungs, liver and kidneys. CO is a poisonous gas produced by the incomplete combustion of fuel.
- Three control mechanisms - Electrostatic Precipitator (removes 99% soot/dust from industrial exhaust), Exhaust Gas Scrubber (removes SO₂ using lime/water spray), Catalytic Converter (removes poisonous gases from automobile exhaust; requires unleaded petrol).
- Delhi was 4th most polluted city in 1990. Following Supreme Court orders, all city buses were converted to CNG by 2002 — economic, efficient and adulteration-proof.
- India adopted BS-VI emission standards in 2018, skipping BS-V, reducing CO₂ and SO₂ levels in Delhi.
Key Points: Major Air Pollutants
- Air pollutants are broadly classified into gaseous pollutants (CO, SO₂, NOₓ, hydrocarbons, ozone) and particulate pollutants (dust, smoke, metals, radioactive particles).
- Gaseous pollutants may be primary (emitted directly) or secondary (formed in the atmosphere, e.g., ozone and photochemical smog).
- Carbon monoxide, mainly from automobile exhausts, is one of the most abundant and dangerous air pollutants.
- Oxides of sulphur and nitrogen, released from fossil fuel combustion and industries, cause respiratory problems and contribute to smog and acid rain.
- Particulate pollutants include solid and liquid particles such as smoke, heavy metals, pesticides and radioactive substances that damage lungs and the environment.
Key Points: Effects of Air Pollution
Key Points: Global Warming
- Global warming — rise in Earth's temperature due to increased greenhouse gases. Earth's temperature rose by 0.6°C in the past century, mostly in the last three decades.
- Causes odd climatic changes like the El Niño effect, melting of polar ice caps and Himalayan snow caps, and submergence of coastal areas.
- Chewang Norphel ("Ice Man of India"), a civil engineer from Ladakh, built 13 artificial glaciers to combat global warming, increasing groundwater recharge and providing irrigation water.
- Artificial glaciers are built at lower elevations so they melt earlier, expanding the growing season.
- Control measures — reduce fossil fuel use, improve energy efficiency, reduce deforestation, plant trees and control population growth.
Key Points: Prevention and Control of Air Pollution
- Control at Source: Air pollution can be reduced by proper planning and siting of industries, improved design of equipment, correct fuel–air mixture, use of fuel additives, and efficient engine design in vehicles.
- Vehicular Pollution Control: Installation of catalytic converters, use of unleaded petrol, adoption of CNG/LPG, and enforcement of Bharat Stage (Euro) emission norms significantly reduce harmful exhaust emissions.
- Industrial Pollution Control Devices: Emissions from industries and power plants are controlled using cyclone collectors, scrubbers, and electrostatic precipitators, which remove particulate matter and harmful gases before release into the atmosphere.
- Legislative and Policy Measures: Laws such as the Air (Prevention and Control of Pollution) Act, 1981 and Environment (Protection) Act, 1986, along with emission standards and fuel regulations, play a crucial role in controlling air pollution.
- Afforestation and Public Awareness: Planting pollution-tolerant trees around urban and industrial areas, along with environmental education and public awareness programmes, helps improve air quality and reduce pollution impacts.
Key Points: Ozone Layer Depletion
- Ozone layer — present in the stratosphere (12–15 km above Earth). Absorbs harmful UV radiation. Thickness measured in Dobson Units (DU).
- CFCs rise to the stratosphere → UV rays release Cl atoms → Cl acts as a catalyst → continuously degrades O₃ → forms ozone hole, particularly over the Antarctic region.
- Other ozone-depleting substances — SO₂, nitrogen oxides and methyl chloroform.
- UV-B (280–322 nm) — damages DNA, causes mutations, skin cancer, ageing and snow blindness/cataract. It can permanently damage the cornea.
- The Montreal Protocol was signed at Montreal, Canada, in 1987 (effective 1989) to control the emission of ozone-depleting substances.
Key Points: Acid Rain
- Acid rain forms when rainwater absorbs industrial gases like CO₂, SO₂, and nitrogen oxides, making it more acidic.
- It harms soil and vegetation, corrodes buildings, damages monuments by reacting with calcium, and reduces visibility.
- It also acidifies water bodies, endangering fish and aquatic life.
- Soil pollution reduces soil fertility and nutrients.
- Waste control is essential to protect soil health.
Key Points: Climate Change
- Climate change refers to long-term changes in temperature, rainfall, wind and other climatic patterns due to natural and human causes.
- Human activities like burning fossil fuels and deforestation increase greenhouse gases, strengthening the greenhouse effect.
- Natural factors such as volcanic activity, ocean circulation and changes in Earth’s orbit also influence climate change.
- Major signs include rising global temperatures, melting glaciers and polar ice, sea-level rise and changing rainfall patterns.
- Future impacts may include frequent heat waves, stronger storms, flooding, ecosystem disruption and socio-economic damage.
Key Points: Kyoto Protocol
- Kyoto Protocol is a legally binding international agreement adopted in 1997 (Kyoto, Japan) under the UNFCCC to reduce greenhouse gas emissions.
- It came into force in 2005 and required industrialized countries to reduce emissions by about 5.2% below 1990 levels during 2008–2012.
- It targeted six greenhouse gases including CO₂, CH₄, N₂O, HFCs, PFCs and SF₆.
- The protocol introduced mechanisms like national emission targets, adaptation fund, accounting, reporting and compliance systems.
- Its main aim was to prevent dangerous human interference with the climate system by stabilizing greenhouse gas concentrations.
Key Points: Water Pollution
- The Water (Prevention and Control of Pollution) Act, 1974, was passed to safeguard water resources. Main sources — domestic sewage, industrial effluents and agricultural run-off.
- BOD (Biochemical Oxygen Demand) is the dissolved oxygen required by microorganisms to decompose organic matter in water. High BOD = high pollution = low oxygen = death of aquatic organisms.
- Algal bloom — excessive growth of planktonic algae due to excess nitrogen and phosphorus. Releases toxins and causes fish mortality. Water hyacinth (Eichhornia crassipes) — "Terror of Bengal" — is an invasive plant that chokes water bodies.
- Eutrophication — natural ageing of a lake by nutrient enrichment. When accelerated by human activities, it is called Cultural/Accelerated Eutrophication, depleting oxygen and killing aquatic life.
- Biomagnification — increase in concentration of toxic pollutants (DDT, mercury) at successive trophic levels. Non-degradable, accumulate in tissues and pass to the next trophic level.
- Thermal pollution — caused by thermal and nuclear power plants releasing hot coolant water, raising water temperature and killing aquatic flora and fauna.
Key Points: Sources of Water Pollution
| Source | Main Pollutants | Effects on Water Bodies |
|---|---|---|
| Household detergents | Phosphates, nitrates, ABS | Eutrophication, algal bloom, water quality deterioration |
| Domestic sewage | Organic waste, pathogens | Decrease in dissolved oxygen (DO), fish mortality, spread of diseases |
| Industrial wastes | Heavy metals, cyanides, toxic chemicals | Toxicity to aquatic life, bioaccumulation, water unfit for use |
| Offshore oil drilling | Oil, mercury | Oil spills, death of marine organisms, coastal pollution |
| Thermal & marine pollution | Hot water, sewage, ship wastes | Reduced oxygen solubility, ecosystem imbalance, marine degradation |
Key Points: Ganga and Yamuna River Pollution Control Initiatives
| Aspect | Ganga Action Plan | Yamuna Action Plan |
|---|---|---|
| Reason | To control pollution due to untreated sewage and waste | To reduce pollution caused by sewage discharge |
| River | River Ganga | River Yamuna |
| Length / Area | About 2,500 km (Gangotri to Bay of Bengal) | States of U.P., Delhi, and Haryana |
| Launched | 1986 | April 1993 |
| Launched by | Late Prime Minister Rajiv Gandhi | Government of India |
| Main Objective | Improve water quality of river Ganga | Control pollution of river Yamuna |
| Key Measures | Sewage interception, diversion, treatment plants | Construction of sewage treatment plants |
| Recent Initiative | Namami Gange Project | Continued under Yamuna Action Plan |
Key Points: Effects of Agrochemicals
- Soil degradation: Excessive use of chemical fertilisers reduces soil microbes, causes mineral imbalance, erosion, and lowers plant disease resistance.
- Water pollution: Nitrates and phosphates reach water bodies, causing eutrophication, oxygen depletion, algal blooms, and death of aquatic life.
- Human health hazards: Nitrate-contaminated water causes methaemoglobinaemia, blue baby syndrome, respiratory disorders and cancer risks.
- Pesticide toxicity: Persistent pesticides (DDT, BHC, aldrin, PCBs) bioaccumulate, damaging kidneys, brain, nervous system and threatening ecological security.
Key Points: Prevention and Control of Water Pollution
- Proper maintenance of water bodies and avoiding the disposal of waste into them helps reduce sewage pollution.
- Use of pesticides and chemical fertilisers should be minimised to prevent water contamination.
- Sewage should be properly treated before being released into rivers and other water bodies.
- Ecological sanitation (Ecosan) uses dry composting toilets to recycle human waste into organic manure, reducing the need for fertilisers.
- Ecosan toilets save water, prevent groundwater contamination, and are useful in water-scarce areas.
- Recycling of sewage water using reverse osmosis (RO) helps solve water scarcity and waste disposal problems.
- Rainwater harvesting and sewage recycling in cities help conserve water and reduce sewage generation.
Key Points: Noise Pollution
- Noise pollution is an undesirable high level of sound. Included as an air pollutant under Air (Prevention and Control of Pollution) Act, 1981, amended in 1987.
- Sources - machines, transportation, construction sites, industries, festivals and public functions.
- Exposure to 150 dB or more causes permanent hearing loss. Other effects - sleeplessness, increased heartbeat, altered breathing, psychological stress and negative impact on the child's learning.
- Control measures - sound absorbent materials, muffling noise, and horn-free zones near schools and hospitals.
- Supreme Court banned loudspeakers at public gatherings after 10 pm. The government has rules against firecrackers and loudspeakers.
Key Points: Effects of Radioactive Pollution
- Health hazards
Radioactive pollution causes severe health problems such as radiation sickness, cancer, anemia, hair loss, skin ulceration and even death at high exposure levels. - Cellular and tissue damage
Ionizing radiations (α, β, γ, X-rays, UV) damage living tissues by causing ionization, leading to destruction of cells, organs and vital systems. - Genetic effects
Radiation induces mutations in genes and chromosomes, resulting in abnormal births, inherited defects and long-term effects on future generations. - Effects through food chain
Radioactive substances enter the food chain and accumulate in organisms, causing indirect contamination and widespread biological damage. - Acute and chronic effects
Low doses cause delayed effects like leukemia, cataract and sterility, while high doses cause radiation sickness and rapid mortality, as seen in Hiroshima and Nagasaki.
Key Points: Land Degradation
- Land degradation
Land degradation is the general wearing away and loss of productivity of land due to factors such as salinization, erosion, deforestation, flooding, water-logging and unplanned urbanization. - Importance of top soil
The fertile top soil (15–20 cm thick) contains essential plant nutrients, and its degradation directly reduces agricultural productivity. - Soil salinization
Soil salinization is caused by the accumulation of soluble salts (mainly sodium, calcium and magnesium salts) which adversely affect soil structure and crop yield. - Causes of salinization
Salinization occurs due to inadequate leaching in semi-arid regions, rising and fluctuating groundwater table, rapid evaporation, saline irrigation water, canal seepage and seawater intrusion in coastal areas. - Extent and impact in India
About 7 million hectares of land in India are salt-affected, especially in coastal, arid, semi-arid and Indo-Gangetic regions, posing a serious threat to sustainable agriculture.
Key Points: Soil Erosion
- Soil erosion is the removal of the top fertile layer of soil by water, wind, and human activities.
- Soil erosion by water includes sheet erosion, rill erosion, gully erosion, leaching, sea erosion, and stream-bank erosion.
- Wind erosion occurs in dry and semi-arid regions where loose soil is carried away by strong winds, reducing soil fertility.
- Human activities such as deforestation, overgrazing, improper farming, and shifting cultivation greatly increase soil erosion.
- Soil erosion reduces agricultural productivity, leads to land degradation, and creates a cycle of poverty.
Key Points: Land and Water Management in India
- Land degradation problem
Population growth, faulty agricultural practices, deforestation, erosion, salinisation, water-logging and urban encroachment have reduced land productivity in India. - Forest conservation measures
The Forest (Conservation) Act, 1980 (amended in 1988) restricts deforestation; measures include controlling shifting cultivation, banning felling above 1000 m, afforestation of hills and protection of catchment areas. - Water management challenges
Floods, siltation, misuse of Himalayan slopes and reservoir damage cause loss of cultivable land and depletion of water resources. - Improving irrigation efficiency
Water-logging and salinity affect over 20% of irrigated land; solutions include lining canals, proper drainage, land levelling and efficient farm-level water management. - Role of groundwater
Groundwater is economical, easily available, less prone to losses and vital in arid regions; its management is guided nationally by the Central Ground Water Board.
Key Points: Solid Waste Management
- Solid waste includes all types of waste from homes, offices, hospitals, etc., and is managed by collection, transport, treatment, and disposal.
- Methods of disposal include open burning and sanitary landfills, but both can cause pollution and health hazards.
- Waste is classified into biodegradable, recyclable, and non-biodegradable; biodegradable waste can decompose naturally.
- Reducing waste generation and promoting recycling (by rag pickers and citizens) is essential for effective waste management.
- Special wastes like biomedical and e-waste require proper treatment, as they contain harmful chemicals and can cause environmental pollution.
Key Points: Deforestation and Its Causes
- India's forest cover reduced from 30% to 19.4% in the 20th century. National Forest Policy 1988 recommends 33% for plains, 67% for hills.
- Effects of deforestation — increased CO₂, loss of biodiversity, disturbed hydrological cycle, soil erosion and desertification.
- Jhum Cultivation (Slash and Burn) — trees cut and burnt, ash used as fertiliser, land farmed, then left to recover. Practised in North-East India.
- Chipko Movement — launched by Chandi Prasad Bhatt and Sundar Lal Bahuguna against tree felling by timber contractors in Uttarakhand.
- Amrita Devi Bishnoi Wildlife Protection Award — given to individuals/communities showing courage in protecting wildlife. Inspired by Amrita Devi, who sacrificed her life in 1731 to protect trees in Rajasthan.
- Joint Forest Management (JFM) — introduced in the 1980s; local communities protect forests and get forest products (fruits, gum, rubber, medicine) in return.
Key Points: Conservation of Forest
- Afforestation and Reforestation
Large-scale afforestation programmes are promoted to increase forest cover, while reforestation helps restore forests that were destroyed earlier, either naturally or through human efforts. - Social Forestry
Started in 1976, social forestry encourages plantation on community and public lands to supply firewood, fodder and small timber, reducing pressure on natural forests and involving local people. - Agroforestry
Agroforestry integrates agriculture, forestry and animal husbandry on the same land to increase productivity, conserve the environment and meet demands for fuel, fodder and timber. - Urban Forestry
Urban forestry focuses on planting trees in towns and cities for aesthetic value, pollution control and improvement of urban environment. - Forest Policies and Legislation
The National Forest Policy (1988) and the Forest (Conservation) Act, 1980 aim to protect forests, prevent diversion of forest land, promote sustainable use and encourage people’s participation in forest conservation.
Key Points:
| Movement / Case | Place & Year | Key People / Groups | Main Issue | Outcome / Significance |
|---|---|---|---|---|
| Bishnoi Agitation | Khejarli, Rajasthan (1731) | Amrita Devi Bishnoi & Bishnoi community | Protection of Khejri trees from felling | 363 people sacrificed lives; inspired conservation ethics; Amrita Devi Bishnoi National Award instituted |
| Chipko Movement | Tehri-Garhwal, Uttarakhand (1970) | Sunder Lal Bahuguna, local women | Indiscriminate tree felling causing floods & erosion | Tree hugging stopped felling; ban on tree cutting in Himalayas |
| Appiko Movement | North Kanara, Karnataka (1983) | Local tribals | Commercial deforestation | Tree hugging forced contractors to stop cutting |
| Silent Valley Agitation | Kerala (1970s–80s) | Conservationists & public | Hydroelectric project threatening biodiversity | Project stopped; unique rainforest ecosystem protected |
| Joint Forest Management (JFM) | West Bengal (1972 onwards) | Forest Dept. & villagers (A.K. Banerjee) | Degraded sal forests | Community participation restored forests; shared benefits ensured |
Key Points: Pollution-Related Diseases
- Mercury pollution causes Minamata disease, leading to severe neurological damage and death due to bioaccumulation in fish.
- Persistent pesticides like DDT biomagnify in food chains and cause hormonal disorders, cancers and neurological problems.
- Exposure to pesticides and heavy metals is a major risk factor for Parkinson’s disease by damaging dopamine-producing neurons.
- Air pollution and smoking are the leading causes of lung cancer, causing uncontrolled growth of lung tissues.
- Bioaccumulation and biomagnification increase the toxicity of pollutants, making humans the most affected at the top of the food chain.
Important Questions [5]
- What do you mean by Biochemical Oxygen Demand (BOD)?
- The scientists from a research institute collected samples of water from sewage pipes of two different cities, A and B. On analysis, the BOD value of the sample from city A was found to be 500 mg/L.
- State any four measures to control noise pollution.
- What is eutrophication?
- Discuss the Various In-situ and Ex-situ Strategies for Conservation of Biodiversity.
Concepts [56]
- Environmental Pollution
- Kinds of Pollutants
- Air Pollution
- Sources of Air Pollution
- Major Air Pollutants
- Effects of Air Pollution
- Greenhouse Effect
- Global Warming
- El Nino Effect
- Prevention and Control of Air Pollution
- Ozone
- Ozone Layer Depletion
- Acid Rain
- Nuclear Winter
- Climate Change
- Kyoto Protocol
- Water Pollution
- Sources of Water Pollution
- Ganga and Yamuna River Pollution Control Initiatives
- Effects of Water Pollution
- Effect of Agrochemicals
- Environmental Acts
- Prevention and Control of Water Pollution
- Eutrophication
- Biochemical Oxygen Demand (BOD)
- Biological Concentration and Biomagnification
- A Case Study of Integrated Waste Water Treatment
- Ecosan Toilets
- Noise Pollution
- Sources of Noise Pollution
- Effects of Noise Pollution
- Decibel
- Prevention and Control of Noise Pollution
- Radioactive Pollution
- Sources of Radioactive Pollution
- Effect of Radioactive Pollution
- Prevention and Control of Radioactive Pollution
- Soil Pollution
- Sources of Soil Pollution
- Effects of Soil Pollution
- Prevention and Control of Soil Pollution
- Land Degradation
- Soil Erosion
- Prevention and Control of Land Degradation
- Land and Water Management in India
- Wasteland Development
- Solid Waste Management
- E-waste Management
- Deforestation and Its Causes
- Consequences of Deforestation
- Conservation of Forests
- Case Study of People's Participation in Conservation of Forests
- Case Study of Organic Farming
- Case Study of Remedy for Plastic Waste
- Pollution-related Diseases
- Occupational Respiratory Disorders
