1. Pollution:

• Pollution: Addition of undesirable substances into the environment due to human activities.
• Pollutants: Physical, chemical or biological agents causing harm to humans, organisms, property, or ecological processes.
• Major types:
  • Air
  • Water
  • Soil
  • Noise
  • Thermal
  • Radiation
• Legal Framework:
  • Environment (Protection) Act, 1986
  • Enacted after Bhopal Gas Disaster (1984)

2. Air Pollution: Definition

• Presence of solid, liquid or gaseous substances (including noise & radiation) in the atmosphere at concentrations harmful to:
  • Human health
  • Other organisms
  • Property
  • Environmental processes

3. Major Sources of Air Pollution

• Burning of fossil fuels (coal, petroleum)
• Thermal power plants
• Industries & mining
• Vehicular emissions
• Construction activities
• Stone quarries

Key Point: Fossil fuels contain nitrogen & sulphur → oxides formed on combustion.

4. Acid Rain & Marble Cancer

• Oxides of Nitrogen (NOx) & Sulphur (SO₂) react with water vapour →
  • Nitric acid (HNO₃)
  • Sulphuric acid (H₂SO₄)
• Precipitation of acids → Acid Rain
• Marble Cancer: Corrosion of marble monuments (e.g., Taj Mahal)

5. Smog

• Mixture of smoke + fog
• Caused by:
  • Suspended particulates
  • Hydrocarbons
  • Condensed water vapour
• Reduces visibility, especially in winter

6. Classification of Pollutants

A. Based on Formation

Primary Pollutants

• Emitted directly
• Examples:
  • CO, CO₂
  • SO₂, NOx
  • Plastics, DDT

Secondary Pollutants

• Formed by chemical reactions
• Example:
  • PAN (Peroxyacetyl Nitrate)

B. Based on Occurrence

Quantitative Pollutants

• Naturally present but harmful beyond threshold
• Examples: CO₂, NOx

Qualitative Pollutants

• Not found naturally
• Human-made
• Examples: DDT, herbicides, fungicides

7. Particulate Pollutants (SPM)

• Suspended matter: dust, soot, fly ash
• Size range: 001 – 500 μm

• 5 (CPCB): Causes maximum health damage
• Diseases:
  • Asthma
  • Bronchitis
  • Pneumoconiosis

8. Fly Ash

Source

• Coal-based thermal power plants

Composition

• Silica (SiO₂)
• Alumina
• Calcium oxide (CaO)
• Heavy metals: Lead, Arsenic, Cobalt

Impacts

• Air & water pollution
• Crop damage (leaf deposition)
• Heavy metal contamination

Uses

• Fly ash bricks
• Cement replacement (up to 35%)
• Road embankments
• Mine filling
• Soil fertility improvement

Policy

• Mandatory use within:
  • 100 km of Thermal Power Plant (construction)
  • 50 km for mine filling

9. Heavy Metal Pollutants

Lead

• Sources:
  • Petrol (TEL)
  • Batteries
  • Paints
• Effects:
  • Nervous system damage
  • Kidney & liver damage
  • Reduced IQ in children
  • Cumulative poisoning

10. Nanoparticles (NPs)

• Size: ~1 nanometre
• Sources:
  • Natural: volcanoes, forest fires, dust storms
  • Man-made: industrial & mechanical processes

Environmental Impacts

• Accumulate in air, water, soil
• Enter food chains
• Produce Reactive Oxygen Species (ROS)

Special Effects

• Asian Brown Clouds → Glacier melting
• Ozone depletion (Cl⁻ radicals)
• Stratospheric cooling (via water vapour & PSCs)

11. Major Gaseous Air Pollutants

Carbon Monoxide (CO)

• Colourless, odourless, toxic
• Source: incomplete combustion
• Forms carboxyhaemoglobin
• Not a GHG but promotes:
  • Ozone formation
  • Methane increase

Carbon Dioxide (CO₂)

• Greenhouse gas
• Causes:
  • Global warming
  • Ocean acidification
• 7% concentration → fatal asphyxiant

Chlorofluorocarbons (CFCs)

• Used in ACs, refrigerators, aerosols
• Cause ozone depletion
• Controlled under Montreal Protocol

Ozone (O₃)

• Stratosphere: Protective
• Troposphere: Toxic pollutant
• Causes:
  • Eye irritation
  • Respiratory issues

Nitrogen Oxides (NOx)

• Produced at high temperatures
• Sources:
  • Engines
  • Power plants
  • Lightning
• Effects:
  • Acid rain
  • Smog
  • Tropospheric ozone

Sulphur Dioxide (SO₂)

• Pungent smell
• Causes acid rain
• Sources:
  • Coal burning
  • Volcanic eruptions
  • Ore roasting

Volatile Organic Compounds (VOCs)

• Easily evaporate
• Sources:
  • Paints
  • Perfumes
  • Furniture polish
• Effects:
  • Headache
  • Nausea
  • Liver damage

12. Other Pollutants

Benzene

• Component of petrol
• Causes cancer & bone marrow failure

Ethylene

• Used for fruit ripening
• Low toxicity
• Ethylene oxide is carcinogenic

Biological Pollutants

• Pollen, fungi, mites
• Cause asthma & allergies

Asbestos

• Causes:
  • Lung cancer
  • Mesothelioma
  • Asbestosis

Radon

• Soil-emitted radioactive gas
• Causes lung cancer in poorly ventilated houses