40  Environmental issues: Local, Regional and Global; Air pollution, Water pollution, Soil pollution, Noise pollution, Waste (solid, liquid, biomedical, hazardous, electronic), Climate change and its Socio-Economic and Political dimensions

40.1 What the Syllabus Covers

The syllabus head bundles five examined topics:

  1. Levels of environmental issues — Local, Regional, Global.
  2. Pollution types — Air, Water, Soil, Noise (+ Thermal, Radiation, Light, Plastic).
  3. Waste streams — Solid, Liquid, Biomedical, Hazardous, Electronic.
  4. Climate change — Causes, mechanisms, impacts.
  5. Socio-economic and political dimensions of climate change.

PYQs: (a) identify the primary vs secondary pollutant, (b) name the AQI category by PM2.5/PM10 level, (c) classify waste (e.g., bio-medical = Yellow bag), (d) name a greenhouse gas by GWP rank, and (e) identify Indian pollution laws / agencies (CPCB, NGT, BS-VI, NCAP, EIA, Bharat Stage).

40.2 Levels of Environmental Issues

TipThree Levels of Environmental Issues
Level Examples
Local Indoor air pollution, garbage dumps, noise around airports, groundwater contamination
Regional Acid rain, smog (NCR winter smog), Yamuna/Ganga pollution, deforestation across states
Global Climate change, ozone depletion, ocean acidification, transboundary plastic pollution

40.3 Air Pollution

Air pollution arises from gases, particulates, and biological substances released into the atmosphere.

40.3.1 Major Air Pollutants

TipCommon Air Pollutants
Pollutant Main sources Health/environment impact
PM10 / PM2.5 Burning fuel, dust, construction Lung, heart disease
CO (carbon monoxide) Incomplete combustion (vehicles) Reduces blood O₂
CO₂ (carbon dioxide) Combustion Greenhouse gas
SO₂ Coal-fired plants Acid rain, respiratory
NOₓ (NO, NO₂) Vehicles, power plants Smog, acid rain
O₃ (ground-level ozone) Photochemical from NOₓ + VOCs Lung damage, secondary pollutant
VOCs Solvents, paints, vehicles Smog precursor
CFCs / HCFCs Refrigerants, aerosols Ozone depletion
Lead (Pb) Older paints, batteries Neurological
Ammonia (NH₃) Fertiliser, livestock Particulate formation

40.3.2 Primary vs Secondary Pollutants

TipPrimary vs Secondary
  • Primary — emitted directly (CO, SO₂, NOₓ, PM, lead).
  • Secondary — formed in atmosphere by reactions (ground-level O₃, PAN, secondary PM, acid rain, smog).

40.3.3 Indoor Air Pollution

Causes: cooking fuel (wood, dung, kerosene), smoking, mould, radon. Ujjwala Yojana (PMUY, 2016) — LPG cylinders to rural women to reduce indoor pollution.

40.3.4 Air Quality Index (AQI) — India

TipIndia’s National AQI (CPCB, 2014)
AQI Value Category
0–50 Good
51–100 Satisfactory
101–200 Moderate
201–300 Poor
301–400 Very Poor
401–500 Severe

Eight pollutants tracked: PM10, PM2.5, NO₂, SO₂, CO, O₃, NH₃, Pb.

40.3.5 Bharat Stage Emission Norms

TipBharat Stage Norms
  • BS-I (2000) → BS-II (2005) → BS-III (2010) → BS-IV (2017) → BS-VI (1 April 2020), skipping BS-V.
  • Based on Euro norms.
  • BS-VI cuts PM and NOₓ dramatically; requires ULSD (Ultra-Low-Sulphur Diesel ≤ 10 ppm sulphur).

40.3.6 National Clean Air Programme (NCAP) — 2019

NCAP aims 40 % reduction in PM (2.5/10) by 2026 (revised target from 2025) across 131 non-attainment cities. Coordinator: CPCB under MoEFCC.

40.4 Water Pollution

40.4.1 Causes and Indicators

TipCauses of Water Pollution
  • Domestic sewage — pathogens, BOD load.
  • Industrial effluents — heavy metals (Hg, Pb, Cr), organic chemicals.
  • Agricultural runoff — fertilisers (N, P) → eutrophication; pesticides.
  • Oil spills.
  • Thermal discharges.
  • Microplastics / nanoplastics.
TipWater Quality Indicators
  • BOD — Biological Oxygen Demand (mg/L of O₂ needed by microbes to decompose organic matter).
  • COD — Chemical Oxygen Demand.
  • DO — Dissolved Oxygen.
  • pH — drinking water should be 6.5–8.5.
  • TDS — Total Dissolved Solids (drinking ≤ 500 mg/L).
  • Coliform count — faecal indicator.
  • Turbidity (NTU).

40.4.2 Eutrophication

Excess nutrients (N, P) cause algal blooms → DO crash → fish kill → “dead zones”. Famous case: Gulf of Mexico dead zone from Mississippi nutrient runoff.

40.4.3 Indian Water Initiatives

TipIndian Water Programmes
  • Namami Gange (2014) — flagship Ganga rejuvenation, NMCG (MoJS).
  • Yamuna Action Plan (since 1993).
  • Atal Bhujal Yojana (2019) — groundwater management.
  • Jal Jeevan Mission (2019) — Har Ghar Jal (tap water to every rural household by 2024).
  • Swachh Bharat Mission (2014) — sanitation.
  • National Water Mission (under NAPCC).

40.4.4 Famous Water-Pollution Events

TipNotable Water Pollution Events
  • Minamata disease, Japan (1956) — mercury poisoning from Chisso Corp. UN Minamata Convention 2013.
  • Itai-itai disease, Japan — cadmium poisoning.
  • Love Canal, NY (1978) — toxic landfill leakage.
  • Bhopal Gas Tragedy (2-3 Dec 1984) — MIC leak, Union Carbide, ~3,800+ deaths; air & water contamination continues.

40.5 Soil Pollution

TipSoil Pollution
  • Causes: pesticides, heavy metals (industrial), fertilisers, plastics, e-waste, leaking landfills, sewage sludge, oil spills.
  • Indicators: pH, organic carbon, NPK levels, microbial activity.
  • Soil degradation forms: Erosion · Salinisation · Waterlogging · Desertification · Loss of organic matter.
  • Anthropogenic soils: Brownfields (industrial-contaminated land).
  • Indian: Soil Health Card Scheme (2015) — MoA&FW.

40.6 Noise Pollution

TipNoise Pollution
  • Measured in decibels (dB).
  • CPCB noise standards (Noise Pollution Rules 2000):
    • Industrial: 75 dB(day)/70 dB(night).
    • Commercial: 65/55.
    • Residential: 55/45.
    • Silence zones (near hospitals/schools/courts): 50/40.
  • Health impacts: Hearing loss, hypertension, sleep disorders, stress.
  • WHO recommends < 70 dB for 24 hr average.

40.7 Thermal, Light, Radiation Pollution

TipOther Pollution Types
  • Thermal pollution — heated water discharged from power plants harms aquatic life.
  • Light pollution — over-illumination; ecological disruption; loss of dark skies.
  • Radiation pollution — natural (radon) + anthropogenic (X-ray, nuclear). Chernobyl 1986 · Fukushima 2011.
  • Microplastic and plastic pollution — Great Pacific Garbage Patch. India banned single-use plastics 1 July 2022.

40.8 Waste Categories

40.8.1 Solid Waste — Five Streams

TipFive Major Waste Streams
Stream Description Indian Rules
Municipal Solid Waste (MSW) Household/commercial waste Solid Waste Management Rules 2016
Biomedical Waste Hospital, lab waste Biomedical Waste Management Rules 2016
Hazardous Waste Toxic, flammable, corrosive Hazardous Waste Management Rules 2016
E-Waste Electronic appliances E-Waste Management Rules 2016 (revised 2022)
Plastic Waste All plastic Plastic Waste Management Rules 2016 (revised 2022 SUP ban)

40.8.2 Biomedical Waste — Colour Coding

TipBiomedical Waste Colour Codes (2016 Rules)
  • Yellow — anatomical, soiled, expired drugs.
  • Red — contaminated recyclable (catheters, syringes).
  • White (translucent) — sharps.
  • Blue — broken glass / metal implants.

40.8.3 E-Waste

TipE-Waste Facts
  • India is among the top 3 e-waste producers globally.
  • Most informal recycling — toxic exposure.
  • E-Waste Rules 2016 (Extended Producer Responsibility — EPR).
  • E-Waste (Management) Rules 2022 strengthen EPR.
  • Basel Convention 1989 governs trans-boundary movement of hazardous waste.

40.8.4 3R / 4R / 5R Hierarchy

TipWaste-Management Hierarchy

5R: Refuse · Reduce · Reuse · Repurpose · Recycle. Below recycle: Recover (energy from waste) → Dispose (landfill).

40.9 Climate Change

40.9.1 The Greenhouse Effect

TipGreenhouse Gases and GWP
Gas Main source GWP (100-year)
Water vapour (H₂O) Evaporation — (feedback gas)
Carbon dioxide (CO₂) Fossil fuel, deforestation 1 (reference)
Methane (CH₄) Livestock, paddy, landfills, fossil-fuel leaks ~28-30
Nitrous oxide (N₂O) Fertilisers, livestock ~265-300
Hydrofluorocarbons (HFCs) Refrigerants 1,000-15,000+
Sulphur hexafluoride (SF₆) Electrical equipment ~23,500
Perfluorocarbons (PFCs) Aluminium production 7,000-12,000
Nitrogen trifluoride (NF₃) Semiconductor ~17,000

40.9.2 Climate Change Science

TipClimate Change Facts
  • CO₂ at ~420 ppm in 2024 vs ~280 ppm pre-industrial.
  • Global temperature already ~1.1-1.2°C above pre-industrial.
  • Paris Agreement (2015) — limit to “well below 2°C”, pursue 1.5°C.
  • IPCC (1988) — Intergovernmental Panel on Climate Change.
  • IPCC AR6 (2021-23) — strongest scientific warning yet.
  • Net Zero by 2050 required globally for 1.5°C; India committed to 2070.

40.9.3 Climate Change Impacts

TipImpacts of Climate Change
  • Sea-level rise (~25 cm since 1900; potentially 0.3-1.1 m by 2100).
  • Glacier melt (Himalayan, Greenland, Antarctic).
  • Ocean acidification — pH dropping from 8.2 to ~8.1.
  • Extreme weather — heatwaves, floods, droughts, cyclones (Amphan, Tauktae, Yaas, Biparjoy, Remal).
  • Biodiversity loss.
  • Agricultural shifts.
  • Vector-borne disease spread (malaria, dengue range expansion).
  • Climate refugees — Bangladesh, Pacific island nations.
  • Food and water security risks.

40.9.4 Mitigation vs Adaptation

TipMitigation vs Adaptation
  • Mitigation — reducing emissions (renewable energy, EVs, afforestation, carbon capture).
  • Adaptation — adjusting to climate impacts (sea walls, drought-resistant crops, heat-action plans).

40.10 Socio-Economic and Political Dimensions

TipEquity Concepts
  • Common but Differentiated Responsibilities (CBDR) — UNFCCC principle, 1992. Developed countries bear greater responsibility.
  • Climate justice — those least responsible suffer most.
  • Polluter Pays Principle — Rio 1992.
  • Precautionary Principle — Rio 1992.
  • Carbon footprint inequalities — top 10 % emitters cause 50 % of emissions.
  • Just transition — fair transition for fossil-fuel workers (coal miners).
  • Loss and Damage Fund — agreed at COP27 (2022); operationalised at COP28 (2023).

40.10.1 Key Indian Frameworks

TipIndian Climate Frameworks
  • NAPCC 2008 — 8 missions.
  • State Action Plans on Climate Change (SAPCC).
  • National Adaptation Fund for Climate Change (NAFCC, 2015).
  • Climate Change Action Plan, Ministry of Environment.
  • Net Zero by 2070 (COP26 Glasgow).
  • Panchamrit pledge (COP26): 500 GW non-fossil by 2030; 50% electricity from RE; 1 bn tonnes CO₂ reduction; 45% intensity cut; net zero 2070.
  • LiFE — Lifestyle for Environment (2021).

40.11 Indian Pollution Regulation

TipIndian Pollution Laws and Agencies
  • Water (Prevention and Control of Pollution) Act, 1974 — first major Indian environment law; created CPCB and SPCBs.
  • Air (Prevention and Control of Pollution) Act, 1981.
  • Environment (Protection) Act, 1986 — umbrella law after Bhopal.
  • Public Liability Insurance Act, 1991.
  • National Environment Tribunal Act, 1995 → National Green Tribunal Act, 2010 (NGT).
  • MoEFCC (Ministry of Environment, Forest and Climate Change).
  • CPCB (Central Pollution Control Board, Delhi) + SPCBs.
  • NGT (2010, New Delhi) — environmental court.
  • EIA Notification 1994, revised 2006.
  • Coastal Regulation Zone Notification.

40.12 Theory Anchors

TipKey Persons, Years, and Concepts
Person / Body Year Contribution
Rachel Carson 1962 Silent Spring; DDT
Stockholm Conference 1972 First UN environment summit; UNEP
CFC-Ozone link 1974 Rowland & Molina (Nobel 1995)
Bhopal Gas Tragedy 1984 MIC leak; led to EP Act 1986
Montreal Protocol 1987 CFC phase-out (most successful environmental treaty)
IPCC 1988 Climate science assessment body
Rio Earth Summit / UNFCCC 1992 CBDR, Polluter Pays, Precautionary
Kyoto Protocol 1997 Emission targets
Paris Agreement 2015 1.5°C ambition
Minamata Convention 2013 Mercury
Basel Convention 1989 Hazardous waste
Stockholm Convention 2001 Persistent Organic Pollutants (POPs)
Rotterdam Convention 1998 Chemical trade consent
IPCC AR6 2021-23 Latest assessment

40.13 Practice Questions

Q 01 AQI Easy

In India's National AQI, an AQI of 350 falls in which category?

  • AModerate
  • BPoor
  • CVery Poor
  • DSevere
View solution
Correct Option: C
301–400 = Very Poor. 401–500 = Severe.
Q 02 BS-VI Medium

India transitioned to BS-VI emission norms on:

  • A1 April 2017
  • B1 April 2020
  • C1 April 2023
  • D1 January 2010
View solution
Correct Option: B
1 April 2020 — skipped BS-V.
Q 03 Pollutant Type Medium

Ground-level ozone (O₃) is a:

  • APrimary pollutant
  • BSecondary pollutant
  • CGreenhouse only
  • DNatural inert gas
View solution
Correct Option: B
Secondary — formed by photochemical reaction of NOₓ and VOCs.
Q 04 Water Medium

BOD (Biological Oxygen Demand) is a measure of:

  • AHeavy metal content
  • BOxygen needed by microbes to decompose organic matter
  • CWater hardness
  • DSalinity
View solution
Correct Option: B
High BOD = high organic pollution.
Q 05 Eutrophication Hard

Algal blooms in lakes due to excess nitrogen/phosphorus runoff cause:

  • AIncrease in DO
  • BEutrophication — DO crash and fish kills
  • CAcidification only
  • DThermal pollution only
View solution
Correct Option: B
Eutrophication. Famous case: Gulf of Mexico dead zone.
Q 06 Minamata Hard

Minamata disease, Japan (1956), was caused by:

  • ALead
  • BCadmium
  • CMercury
  • DArsenic
View solution
Correct Option: C
Mercury from Chisso Corporation. UN Minamata Convention 2013.
Q 07 Bhopal Medium

The Bhopal Gas Tragedy (December 1984) was caused by the leak of:

  • AMethyl isocyanate (MIC)
  • BCFC
  • CChlorine
  • DAmmonia
View solution
Correct Option: A
Methyl isocyanate (MIC) from Union Carbide plant. 2-3 Dec 1984.
Q 08 EP Act Medium

The Environment (Protection) Act, India's umbrella environment law, was enacted in:

  • A1974
  • B1981
  • C1986
  • D2010
View solution
Correct Option: C
EP Act 1986, following Bhopal (1984). Water Act 1974; Air Act 1981.
Q 09 NGT Medium

India's National Green Tribunal (NGT) was established in:

  • A1986
  • B1995
  • C2010
  • D2014
View solution
Correct Option: C
NGT Act 2010. India's environmental court.
Q 10 GHG GWP Hard

The Global Warming Potential (GWP, 100-year) of methane relative to CO₂ is approximately:

  • A1
  • B~28
  • C~298
  • D~23,500
View solution
Correct Option: B
CO₂ = 1; CH₄ ≈ 28-30; N₂O ≈ 265-300; SF₆ ≈ 23,500.
Q 11 IPCC Medium

IPCC, the Intergovernmental Panel on Climate Change, was established in:

  • A1972
  • B1988
  • C1992
  • D2000
View solution
Correct Option: B
1988 by WMO + UNEP. Nobel Peace 2007 with Al Gore.
Q 12 Ozone Medium

The Montreal Protocol (1987) aims to phase out:

  • AGreenhouse gases
  • BOzone-depleting substances (CFCs, HCFCs)
  • CHeavy metals
  • DPlastics
View solution
Correct Option: B
Montreal Protocol 1987 — phasing out CFCs/HCFCs. Most successful environmental treaty.
Q 13 Biomedical Color Hard

Under India's Biomedical Waste Rules 2016, anatomical and soiled waste is placed in the:

  • AYellow bag
  • BRed bag
  • CBlue bag
  • DWhite (translucent) container
View solution
Correct Option: A
Yellow — anatomical, soiled, expired drugs. Red = contaminated recyclable; White = sharps; Blue = broken glass/metal.
Q 14 Basel Hard

The Basel Convention (1989) regulates:

  • AGreenhouse-gas emissions
  • BTrans-boundary movement of hazardous waste
  • CMarine fisheries
  • DPlastic packaging
View solution
Correct Option: B
Basel Convention 1989 — trans-boundary hazardous waste.
Q 15 CPCB Medium

India's Central Pollution Control Board (CPCB) was established under:

  • AWater Act 1974
  • BAir Act 1981
  • CEP Act 1986
  • DNGT Act 2010
View solution
Correct Option: A
Water Act 1974 created CPCB and SPCBs.
Q 16 CBDR Hard

"Common but Differentiated Responsibilities (CBDR)", a principle of international environmental law, was articulated at:

  • AStockholm 1972
  • BRio 1992
  • CKyoto 1997
  • DParis 2015
View solution
Correct Option: B
Rio Declaration 1992 — Principle 7.
Q 17 NCAP Medium

India's National Clean Air Programme (NCAP) was launched in:

  • A2014
  • B2019
  • C2021
  • D2023
View solution
Correct Option: B
NCAP 2019 — 40 % PM reduction by 2026 in 131 non-attainment cities.
Q 18 Loss & Damage Hard

The "Loss and Damage Fund" for climate-vulnerable countries was agreed at:

  • ACOP21 Paris 2015
  • BCOP26 Glasgow 2021
  • CCOP27 Sharm el-Sheikh 2022
  • DCOP28 Dubai 2023
View solution
Correct Option: C
COP27, Sharm el-Sheikh, 2022. Operationalised at COP28 Dubai 2023.
Q 19 SUP Ban Hard

India banned single-use plastics (SUP) effective:

  • A1 January 2020
  • B1 July 2022
  • C1 January 2023
  • D2 October 2019
View solution
Correct Option: B
1 July 2022 — Plastic Waste Management Amendment Rules 2021.
Q 20 Match Hard

Match each international convention with its target:

(i) Montreal Protocol (a) Mercury
(ii) Basel Convention (b) CFCs / Ozone
(iii) Minamata Convention (c) Persistent Organic Pollutants
(iv) Stockholm Convention (d) Hazardous waste
  • A(i)-b, (ii)-d, (iii)-a, (iv)-c
  • B(i)-a, (ii)-b, (iii)-c, (iv)-d
  • C(i)-c, (ii)-d, (iii)-a, (iv)-b
  • D(i)-d, (ii)-a, (iii)-b, (iv)-c
View solution
Correct Option: A
Montreal → CFCs; Basel → Hazardous waste; Minamata → Mercury; Stockholm → POPs.

40.14 Quick Recall

ImportantQuick recall
  • 3 levels: Local · Regional · Global.
  • Air pollutants: PM10/PM2.5 · CO · CO₂ · SO₂ · NOₓ · O₃ · VOCs · CFCs · Pb · NH₃.
  • Primary vs Secondary: primary emitted directly (CO, SO₂, NOₓ); secondary formed in atmosphere (O₃, PAN, acid rain, smog, secondary PM).
  • AQI India (CPCB 2014): Good 0-50 · Satisfactory 51-100 · Moderate 101-200 · Poor 201-300 · Very Poor 301-400 · Severe 401-500. 8 pollutants: PM10, PM2.5, NO₂, SO₂, CO, O₃, NH₃, Pb.
  • Bharat Stage: BS-I 2000 → BS-VI 1 April 2020 (skipped BS-V).
  • NCAP 2019: 40 % PM cut by 2026 in 131 non-attainment cities. Ujjwala 2016: indoor air, LPG.
  • Water indicators: BOD · COD · DO · pH · TDS · Coliform · Turbidity (NTU).
  • Eutrophication: N/P runoff → algal bloom → DO crash → dead zone.
  • Famous pollution events: Minamata Hg (1956 Japan) · Itai-itai Cd · Love Canal NY · Bhopal MIC 2-3 Dec 1984.
  • Indian water: Namami Gange (2014, NMCG) · Yamuna · Atal Bhujal 2019 · Jal Jeevan Mission 2019 · Swachh Bharat 2014.
  • Soil pollution: pesticides, metals, plastics, e-waste. Soil Health Card 2015. Degradation: Erosion · Salinisation · Waterlogging · Desertification.
  • Noise (Rules 2000): Industrial 75/70 · Commercial 65/55 · Residential 55/45 · Silence zones 50/40 dB(day/night).
  • Waste streams (5): MSW · Biomedical · Hazardous · E-waste · Plastic. All under Rules 2016, revised.
  • Biomedical colour codes: Yellow (anatomical/soiled) · Red (contaminated recyclable) · White (sharps) · Blue (glass/metal).
  • 5R hierarchy: Refuse · Reduce · Reuse · Repurpose · Recycle.
  • Climate change: CO₂ ~420 ppm (vs 280 pre-industrial); already +1.1-1.2°C. Paris 2015: 1.5°C.
  • GHG GWP (100-yr): CO₂ 1 · CH₄ ~28 · N₂O ~298 · HFCs 1k-15k · SF₆ ~23,500.
  • IPCC 1988 (WMO + UNEP); Nobel Peace 2007. AR6 2021-23.
  • Impacts: sea-level rise, glacier melt, ocean acidification (pH 8.2→8.1), extreme weather, biodiversity loss, agricultural shifts, climate refugees.
  • Mitigation vs Adaptation.
  • Political concepts: CBDR (Rio 1992) · Polluter Pays · Precautionary Principle · Just Transition · Climate Justice · Loss & Damage Fund (COP27 2022).
  • Indian climate: NAPCC 2008 (8 missions) · SAPCC · NAFCC 2015 · Net Zero 2070 Glasgow · Panchamrit · LiFE 2021.
  • Indian laws: Water Act 1974 (CPCB) · Air Act 1981 · EP Act 1986 (umbrella, post-Bhopal) · NGT Act 2010 · EIA Notification 1994/2006 · CRZ.
  • International conventions: Montreal 1987 (CFCs) · Basel 1989 (hazardous waste) · Rotterdam 1998 (chemical trade) · Stockholm 2001 (POPs) · Minamata 2013 (Hg).