Complete  notes on Pollution-Air, water, Soil and Noise  for BPSC and Other Competitive Exams in 2025

Complete  notes on Pollution-Air, water, Soil and Noise  for BPSC and Other Competitive Exams in 2025

General Science- 23(Environment)

Pollution – Air, Water, Soil and Noise

1. Introduction

Pollution is the undesirable change in the physical, chemical, or biological characteristics of air, water, or land that may harm human health, living organisms, or the environment.

2. Air Pollution

Definition:

Presence of substances in the atmosphere in concentrations sufficient to cause harm.

Major Air Pollutants

1. Primary Pollutants (emitted directly)
   • CO, SO₂, NOx, particulate matter (PM₁₀, PM₂.₅), hydrocarbons, lead
2. Secondary Pollutants (formed by chemical reaction in atmosphere)
   • Ozone (O₃), PAN (Peroxyacetyl nitrate), smog components

Sources

• Natural: Volcanic eruptions, forest fires, dust storms, pollen
• Anthropogenic: Vehicles, industries, burning of fossil fuels, biomass burning, waste incineration

Effects

• Human Health: Respiratory diseases, cardiovascular problems, cancers
• Environment: Acid rain, smog, reduced visibility, ozone depletion
• Climate: Greenhouse gas accumulation → global warming

Control Measures

• Bharat Stage VI vehicle norms (India)
• Scrubbers & electrostatic precipitators in industries
• Promotion of public transport & EVs
• Banning single-use plastics & stubble burning control

3. Water Pollution

Definition:

Contamination of water bodies making it unfit for use.

Major Water Pollutants

• Organic wastes (sewage, food waste)
• Pathogens (bacteria, viruses, protozoa)
• Chemicals (pesticides, heavy metals, fertilizers)
• Oil spills, thermal discharges

Sources

• Domestic sewage, industrial effluents, agricultural runoff
• Oil tankers & drilling rigs
• Acid mine drainage

Effects

• Human Health: Water-borne diseases – cholera, hepatitis, typhoid
• Aquatic Life: Eutrophication (excess nutrients → algal bloom → oxygen depletion)
• Ecosystem: Disruption of aquatic food chains, biodiversity loss

Control Measures

• Sewage treatment plants (STPs)
• Zero Liquid Discharge (ZLD) in industries
• River rejuvenation programs – Namami Gange
• Regulation of pesticides & fertilizers

4. Soil Pollution

Definition:

Presence of toxic chemicals or alteration of soil environment leading to reduced fertility or harmful effects.

Major Soil Pollutants

• Pesticides & herbicides
• Heavy metals (lead, mercury, cadmium)
• Industrial waste, radioactive substances
• Plastic & e-waste

Sources

• Excessive agrochemicals
• Improper waste disposal
• Industrial spills & mining
• Acid rain fallout

Effects

• Loss of soil fertility & crop yield
• Contamination of food chain (bioaccumulation)
• Desertification & erosion
• Toxicity to soil microflora & fauna

Control Measures

• Organic farming & integrated pest management
• Proper hazardous waste management
• Phytoremediation (plants to absorb toxins)
• Ban on persistent organic pollutants (POPs)

5. Noise Pollution

Definition:

Unwanted or harmful sound exceeding permissible limits.

CPCB Noise Standards (India):

• Residential: Day 55 dB, Night 45 dB
• Industrial: Day 75 dB, Night 70 dB
• Silence Zone (Hospitals, Schools): Day 50 dB, Night 40 dB

Sources

• Transportation (road, rail, air)
• Construction, industrial machinery
• Loudspeakers, music systems, festivals
• Household appliances

Effects

• Human Health: Hearing loss, stress, hypertension, sleep disturbance
• Wildlife: Disrupts communication, breeding, migration

Control Measures

• Noise barriers, soundproofing
• Ban on loudspeakers at night (10 PM – 6 AM)
• Maintenance of vehicles & machinery
• Zoning of residential & industrial areas

6. Indian & International Laws / Initiatives

• Air (Prevention and Control of Pollution) Act, 1981
• Water (Prevention and Control of Pollution) Act, 1974
• Environment Protection Act, 1986
• Noise Pollution (Regulation and Control) Rules, 2000
• National Clean Air Programme (NCAP) – Target: 20–30% PM reduction by 2024
• National Ganga River Basin Authority
• Basel Convention – Control of transboundary movement of hazardous wastes
• Paris Agreement (2015) – Climate change mitigation

7. Current Affairs Pointers for Exams

• Air Quality Index (AQI) categories by CPCB
• BS-VI norms timeline
• Jal Jeevan Mission & Namami Gange
• Recent AQI rankings of Indian cities
• Bans on single-use plastics
• National Green Tribunal (NGT) rulings on stubble burning & Yamuna cleaning

MCQs for Practice

Q1. Which pollutant is a major cause of photochemical smog?
A) SO₂
B) Ozone
C) CO₂
D) Methane

Q2. Which of the following causes eutrophication?
A) Oil spill
B) Excess nutrients
C) Noise pollution
D) Thermal discharge

Q3. CPCB noise standard for silence zones during night is:
A) 55 dB
B) 45 dB
C) 40 dB
D) 35 dB

Q4. Which Act in India was enacted first?
A) Air (Prevention and Control of Pollution) Act
B) Environment Protection Act
C) Water (Prevention and Control of Pollution) Act
D) Noise Pollution Rules

Q5. In aquatic food chains, biomagnification of pesticides occurs because:
A) Producers absorb more than consumers
B) Consumers excrete pollutants slowly
C) Pollutants degrade easily
D) Fish avoid pollutants