UPSC CSE Prelims
Environmental Pollution Previous Year Questions (PYQs)
Showing solved Previous Year Questions for Chapter: Environmental Pollution
Topic Breakdown: Scroll →
Bisphenol A (BPA) , a cause of concern, is a structural/key component in the manufacture of which of the following kinds of plastics?
Detailed Explanation:
Answer: Option 2 — Polycarbonate
Bisphenol A (BPA) is a key structural component in the manufacture of polycarbonate plastics. Polycarbonates are widely used in consumer products such as water bottles, food storage containers, eyeglass lenses, and CDs/DVDs. BPA has raised significant health concerns as it can act as an endocrine disruptor, interfering with the body's hormonal system.
📝 Short Notes: Types of Plastics and BPA
| Plastic Type | Common Uses | Contains BPA? |
|---|---|---|
| Polycarbonate (PC) | Water bottles, food containers, eyeglass lenses, CDs/DVDs, baby bottles | Yes – BPA is a key component |
| Polyethylene Terephthalate (PET) | Beverage bottles, food packaging, synthetic fibers | No |
| Low Density Polyethylene (LDPE) | Plastic bags, squeeze bottles, container lids | No |
| Polyvinyl Chloride (PVC) | Pipes, flooring, wire insulation, medical tubing | No |
| High Density Polyethylene (HDPE) | Milk jugs, detergent bottles, toys | No |
- BPA Health Concerns: Acts as endocrine disruptor, mimics estrogen, linked to reproductive issues, developmental problems, and metabolic disorders
- BPA-Free Alternatives: Many manufacturers now produce BPA-free polycarbonates or use alternative plastics
- Regulation: Several countries have banned BPA in baby bottles and food contact materials
Magnetite particles, suspected to cause neurodegenerative problems, are generated as environmental pollutants from which of the following?
- Brakes of motor vehicles
- Engines of motor vehicles
- Microwave stoves within homes
- Power plants
- Telephone lines
Select the correct answer using the code given below
Detailed Explanation:
Answer: Option 2 — 1, 2 and 4 Only
Magnetite nanoparticles are iron oxide particles released from high-temperature combustion and mechanical friction processes. They are generated from motor vehicle brakes (friction), engines (combustion), and power plants (fossil fuel burning), but not from microwave stoves or telephone lines which do not involve such processes.
✅ Statement 1 – Correct: Brakes of motor vehicles generate magnetite through friction and mechanical wear between brake pads and discs, producing iron-rich particulate matter that oxidizes to magnetite nanoparticles.
✅ Statement 2 – Correct: Engines of motor vehicles produce magnetite as a byproduct of high-temperature combustion of fuel and wear of engine components, releasing these particles as environmental pollutants.
❌ Statement 3 – Incorrect: Microwave stoves use electromagnetic radiation to heat food without combustion or mechanical abrasion, and therefore do not release magnetite particles.
✅ Statement 4 – Correct: Power plants, particularly coal-fired ones, emit magnetite through high-temperature combustion of fossil fuels, producing fly ash containing magnetic iron oxides.
❌ Statement 5 – Incorrect: Telephone lines carry electrical or optical signals and generate electromagnetic fields but do not undergo physical processes that emit magnetite particles.
📝 Short Notes: Magnetite Pollution Sources
- Magnetite (Fe₃O₄): Iron oxide nanoparticles suspected to cause neurodegenerative diseases like Alzheimer's when inhaled, as they can cross the blood-brain barrier.
- Vehicle Sources: Brake wear (friction-generated particles) and engine combustion are major urban sources of airborne magnetite.
- Industrial Sources: Coal-fired power plants and other fossil fuel combustion facilities release magnetite in fly ash and exhaust gases.
- Health Concern: Magnetite nanoparticles found in human brain tissue samples, particularly in urban populations exposed to traffic pollution.
- Non-Sources: Household appliances like microwaves and infrastructure like telephone lines do not generate magnetite as they lack combustion or mechanical friction processes.
With reference to furnace oil, consider the following statements:
- It is a product of oil refineries.
- Some industries use it to generate power.
- Its use causes sulphur emissions into Environment.
Which of the statements given above are correct?
Detailed Explanation:
Answer: Option 4 — 1, 2 and 3
All three statements about furnace oil are correct. Furnace oil is a heavy residual fuel produced during petroleum refining, widely used in industries for power generation and heating, and its combustion releases significant sulfur emissions causing environmental pollution.
✅ Statement 1 – Correct: Furnace oil is a dark, viscous residual fuel product obtained from oil refineries by blending heavier fractions of crude oil distillation.
✅ Statement 2 – Correct: Industries such as cement, steel, textiles, and power plants use furnace oil in boilers and furnaces to generate heat and power.
✅ Statement 3 – Correct: Furnace oil contains high sulfur content (2-4%), and its combustion releases sulfur dioxide (SO₂) and other pollutants, contributing to air pollution and acid rain.
📝 Short Notes: Furnace Oil
- Definition: A dark, viscous residual fuel oil derived from petroleum refining, also known as heavy fuel oil or residual fuel oil.
- Production: Obtained by blending the heavier components left after distillation of crude oil; contains high carbon and sulfur content.
- Industrial Uses: Used in boilers, furnaces, and kilns in cement, steel, textile, chemical, and power generation industries.
- Sulfur Content: Contains 2-4% sulfur, significantly higher than diesel or petrol; releases SO₂ and particulate matter upon combustion.
- Environmental Impact: Major contributor to air pollution, acid rain, and respiratory health issues; many countries are phasing it out in favor of cleaner fuels.
- Alternatives: Natural gas, low-sulfur heavy oil, biomass, and renewable energy sources are being adopted to replace furnace oil in industries.
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Steel slag can be the material for which of the following?
- Construction of base road
- Improvement of agricultural soil
- Production of cement
Select the correct answer using the code given below:
Detailed Explanation:
Answer: Option 4 — 1, 2 and 3 only
Steel slag, a by-product of steel manufacturing, has multiple applications in construction, agriculture, and cement production. All three statements correctly identify valid uses of steel slag.
✅ Statement 1 – Correct: Steel slag is widely used in road base construction due to its high strength, durability, excellent drainage properties, and cost-effectiveness.
✅ Statement 2 – Correct: Steel slag can be used as a soil amendment in agriculture to improve drainage, provide essential nutrients like calcium and magnesium, correct soil pH, and enhance soil structure.
✅ Statement 3 – Correct: Steel slag can be used as a partial substitute for limestone and other raw materials in cement production, reducing environmental impact and conserving natural resources.
📝 Short Notes: Steel Slag Utilization
- Definition: Steel slag is a by-product generated during steel manufacturing in furnaces, consisting primarily of calcium, iron, silicon, and magnesium oxides.
- Road Construction: Used as aggregate in asphalt concrete, road base material, and railway ballast due to high abrasion resistance and load-bearing capacity.
- Agricultural Use: Acts as a soil conditioner, neutralizes acidic soils, supplies micronutrients, and improves soil permeability.
- Cement Industry: Can replace 10-15% of clinker in cement production, reducing CO₂ emissions and energy consumption.
- Other Applications: Used in wastewater treatment, coastal protection structures, and as a raw material for mineral wool production.
- Environmental Benefits: Reduces landfill waste, conserves natural resources, and supports circular economy principles in steel industry.
Which of the following are the reasons/factors for exposure to benzene pollution?
- Automobile exhaust
- Tobacco smoke
- Wood burning
- Using varnished wooden furniture
- Using products made of polyurethane
Select the correct answer using the code given below:
Detailed Explanation:
Answer: Option 1 — 1, 2 and 3 only
Benzene is a colorless, volatile organic compound and a known carcinogen present in the environment through various natural and anthropogenic sources. The main sources of benzene exposure include automobile exhaust (as benzene is present in petrol), tobacco smoke (both active and passive), and wood burning (due to incomplete combustion). Varnished wooden furniture and polyurethane products are not significant sources of benzene pollution.
✅ Statement 1 – Correct: Automobile exhaust, especially from petrol-driven vehicles, is a major source of benzene as it is a component of petroleum products.
✅ Statement 2 – Correct: Tobacco smoke contains benzene and is a significant source of exposure for both smokers and passive smokers.
✅ Statement 3 – Correct: Wood burning releases benzene through incomplete combustion, along with other pollutants like polycyclic aromatic hydrocarbons (PAHs).
❌ Statement 4 – Incorrect: Varnished wooden furniture may emit benzene during application but once cured, it is not a significant source of benzene pollution.
❌ Statement 5 – Incorrect: Polyurethane products are primarily associated with other volatile organic compounds (VOCs), not benzene.
📝 Short Notes: Benzene Pollution
- Nature: Benzene (C₆H₆) is a colorless, highly flammable liquid with a sweet odor, classified as a Group 1 carcinogen by IARC.
- Major Sources: Automobile emissions (petrol combustion), tobacco smoke, industrial processes, petroleum refineries, and incomplete combustion of organic materials (wood, coal).
- Health Effects: Prolonged exposure causes blood disorders, anemia, leukemia, immune system suppression, and reproductive health issues.
- Indoor Sources: Tobacco smoke, attached garages (vehicle emissions), and certain paints/solvents during application.
- Occupational Exposure: Workers in petroleum refineries, chemical plants, rubber manufacturing, and printing industries face higher risks.
- Regulatory Standards: WHO air quality guideline for benzene is minimal (no safe level); ambient air standards vary by country to limit exposure.
Consider the following statements:
- Coal ash contains arsenic, lead and mercury.
- Coal-fired power plants release Sulphur dioxide and oxides of nitrogen into the environment.
- High ash content is observed in Indian coal.
Which of the statements given above is/are correct?
Detailed Explanation:
Answer: Option 4 — 1, 2 and 3
All three statements about coal combustion and Indian coal characteristics are correct. Coal ash contains heavy metals, coal-fired power plants release sulfur and nitrogen oxides, and Indian coal is characterized by high ash content.
✅ Statement 1 – Correct: Coal ash, a by-product of coal combustion, contains toxic heavy metals including arsenic, lead, and mercury, which can leach into water bodies and contaminate soil, posing environmental and health hazards.
✅ Statement 2 – Correct: Coal-fired power plants release sulfur dioxide (SO₂) and nitrogen oxides (NOₓ) during combustion, which contribute to acid rain, respiratory issues, smog formation, and overall air pollution.
✅ Statement 3 – Correct: Indian coal, especially from eastern and central regions, has high ash content (30-50%), which reduces its calorific value, increases pollution levels, and results in large quantities of fly ash generation in thermal power plants.
📝 Short Notes: Coal Combustion and Environmental Impact
- Coal Ash Composition: Contains heavy metals (arsenic, lead, mercury, chromium, cadmium) that are toxic and carcinogenic; improper disposal can contaminate groundwater and soil.
- Air Pollutants from Coal Plants: Release SO₂ (causes acid rain), NOₓ (forms ground-level ozone and smog), particulate matter (PM2.5, PM10), CO₂ (greenhouse gas), and mercury emissions.
- Indian Coal Characteristics: High ash content (30-50% compared to 10-15% in imported coal), low calorific value (3000-4000 kcal/kg), and high moisture content.
- Fly Ash Utilization: India generates over 200 million tonnes of fly ash annually; used in cement manufacturing, brick making, road construction, and land filling.
- Environmental Regulations: MoEFCC mandates 100% fly ash utilization; thermal power plants must maintain electrostatic precipitators and FGD (Flue Gas Desulfurization) systems.
In India, the use of carbofuran, methyl parathion, phorate and triazophos is viewed with apprehension. These chemicals are used as
Detailed Explanation:
Answer: Option 1 — pesticides in agriculture
Carbofuran, methyl parathion, phorate, and triazophos are highly toxic organophosphate and carbamate pesticides used in agriculture. These chemicals are viewed with apprehension due to their severe toxicity to humans, non-target organisms, and the environment, leading to recommendations for their ban or phase-out by the Anupam Verma Committee in India.
📝 Short Notes: Hazardous Pesticides in India
- Organophosphates and Carbamates: These are two major classes of chemical pesticides that inhibit acetylcholinesterase enzyme, causing neurotoxic effects in pests and potentially in humans.
- Carbofuran: A carbamate insecticide banned in many countries; highly toxic to birds, fish, and mammals; used for soil and foliar treatment.
- Methyl Parathion: An organophosphate insecticide with extreme acute toxicity; banned or restricted globally due to human poisoning cases.
- Phorate: A systemic organophosphate insecticide; extremely hazardous with high dermal and oral toxicity.
- Triazophos: An organophosphate insecticide; moderately to highly toxic with environmental persistence concerns.
- Anupam Verma Committee (2013): Reviewed 66 pesticides banned abroad but used in India; recommended banning 13 and restricting others, leading to regulatory action by the Ministry of Agriculture.
- Government Action: Progressive banning and phase-out of hazardous pesticides to promote safer agricultural practices and protect public health and environment.
In the context of which one of the following are the terms ‘pyrolysis and plasma gasification’ mentioned?
Detailed Explanation:
Answer: Option 4 — Waste-to-energy technologies
Pyrolysis and plasma gasification are advanced thermochemical waste-to-energy technologies that convert waste materials into useful energy products. Pyrolysis involves heating organic waste in an oxygen-deficient environment to produce syngas, bio-oil, and char, while plasma gasification uses extremely high temperatures (created by plasma torches) to break down waste into syngas rich in hydrogen and carbon monoxide. Both processes offer sustainable solutions for waste management while generating energy, making them key technologies in the circular economy framework.
📝 Short Notes: Waste-to-Energy Technologies
- Pyrolysis: Thermal decomposition of organic materials at 300-900°C in the absence of oxygen, producing syngas, bio-oil, and biochar. Used for plastic waste, biomass, and municipal solid waste treatment.
- Plasma Gasification: Uses plasma torches creating temperatures above 3000°C to convert waste into syngas and inert slag. Can process hazardous and mixed waste streams effectively.
- Products: Syngas (mixture of H₂, CO, CH₄) can be used for electricity generation, as chemical feedstock, or converted to liquid fuels.
- Advantages: Significant waste volume reduction (up to 90%), minimal landfill requirement, energy recovery, and reduced greenhouse gas emissions compared to conventional incineration.
- Applications in India: Several pilot projects and commercial plants are being explored under Swachh Bharat Mission and Smart Cities initiatives for sustainable waste management.
Consider the following:
- Carbon monoxide
- Methane
- Ozone
- Sulphur dioxide
Which of the above are released into the atmosphere due to the burning of crop/biomass residue?
Detailed Explanation:
Answer: Option 4 — 1, 2, 3 and 4
The burning of crop/biomass residue releases multiple pollutants into the atmosphere through incomplete combustion and chemical reactions. All four pollutants mentioned—carbon monoxide, methane, sulphur dioxide, and ozone—are associated with biomass burning, either as direct emissions or secondary formation.
✅ Carbon Monoxide (CO) – Released: Incomplete combustion of organic matter directly produces carbon monoxide, a toxic gas that reduces oxygen-carrying capacity in blood and contributes to air pollution.
✅ Methane (CH₄) – Released: Biomass burning releases methane, a potent greenhouse gas with 25 times the global warming potential of CO₂ over a 100-year period, contributing significantly to climate change.
✅ Ozone (O₃) – Formed: While not directly emitted, ozone forms as a secondary pollutant when nitrogen oxides (NOₓ) and volatile organic compounds (VOCs) from biomass burning react in the presence of sunlight, creating ground-level ozone.
✅ Sulphur Dioxide (SO₂) – Released: When biomass containing sulfur compounds burns, it releases sulphur dioxide, which causes respiratory problems and contributes to acid rain formation.
📝 Short Notes: Biomass Burning Emissions
- Primary Pollutants: Direct emissions include CO, CH₄, SO₂, NOₓ, particulate matter (PM2.5 and PM10), and black carbon
- Secondary Pollutants: Ground-level ozone forms when NOₓ and VOCs react in sunlight; acid rain forms from SO₂ and NOₓ reactions with water vapor
- Greenhouse Gases: Biomass burning releases CO₂, CH₄, and N₂O, contributing approximately 40% of global CO emissions and 20% of tropospheric ozone precursors
- Health Impacts: Particulate matter and toxic gases cause respiratory diseases, cardiovascular problems, and reduced visibility; CO interferes with oxygen transport in blood
- Environmental Impact: Contributes to air pollution, smog formation, acid deposition, soil nutrient loss, and climate change through greenhouse gas emissions
- Major Sources: Agricultural residue burning (stubble burning in Punjab/Haryana), forest fires, and traditional biomass fuel use for cooking and heating
In India, ‘extended producer responsibility’ was introduced as an important feature in which of the following?
Detailed Explanation:
Answer: Option 3 — The e-Waste Management and Handling Rules, 2011
Extended Producer Responsibility (EPR) was first introduced as a key feature in India through the e-Waste Management and Handling Rules, 2011. Under EPR, producers of electrical and electronic equipment are made responsible for the collection, channelization, and proper disposal of e-waste generated from their products after end-of-life. This principle was later extended to other waste management rules including the Plastic Waste Management Rules, 2016, but the e-Waste Rules of 2011 marked its first significant introduction in Indian environmental legislation.
📝 Short Notes: Extended Producer Responsibility (EPR) in India
| Rules/Regulations | Year | EPR Provision |
|---|---|---|
| Bio-medical Waste Management and Handling Rules | 1998 | No EPR provision; focused on healthcare facility responsibilities |
| e-Waste Management and Handling Rules | 2011 | First introduction of EPR - Producers responsible for collection and channelization of e-waste |
| Plastic Waste Management Rules | 2016 | EPR extended to plastic waste - Producers, importers, brand owners accountable |
| e-Waste Management Rules (Revised) | 2016 | Strengthened EPR with collection targets and penalties |
| Battery Waste Management Rules | 2022 | EPR provisions for battery producers |
- EPR Concept: Makes producers responsible for the entire lifecycle of their products, especially post-consumer waste management
- Objectives: Reduce environmental burden, promote circular economy, ensure proper waste disposal and recycling
- Implementation: Producers must establish collection mechanisms, collaborate with authorized recyclers, and meet specified collection targets
- Recent Developments: EPR certificates tradable on centralized portal; Digital tracking of waste collection
Why is there a great concern about the ‘microbeads’ that are released into the environment?
Detailed Explanation:
Answer: Option 1 — They are considered harmful to marine ecosystems.
Microbeads are tiny plastic particles (typically less than 5mm) used in cosmetics and personal care products that are released into water bodies through drainage systems. Marine animals like fish, shellfish, and plankton easily ingest these microbeads due to their small size, which can block their digestive systems leading to starvation or death. Additionally, microbeads absorb pollutants and toxins from water, concentrating them in the food chain and potentially harming larger predators, including humans.
📝 Short Notes: Microbeads and Marine Pollution
- Definition: Microbeads are solid plastic particles measuring less than 5mm in diameter, primarily made of polyethylene or polypropylene.
- Sources: Commonly found in facial scrubs, toothpastes, body washes, and other exfoliating personal care products.
- Environmental Pathway: They pass through wastewater treatment plants (too small to be filtered) and enter rivers, lakes, and oceans.
- Marine Impact: Mistaken for food by marine organisms, causing bioaccumulation in the food chain and physical harm to aquatic life.
- Toxic Absorption: Microbeads act as sponges for persistent organic pollutants (POPs) and heavy metals present in water.
- Global Action: Many countries including USA, UK, Canada, and India have banned or restricted the use of microbeads in cosmetics.
- India's Stand: India banned the manufacture of cosmetics containing microbeads in 2020 to protect marine ecosystems.
As per the Solid Waste Management Rules, 2016 in India, which one of the following statements is correct?
Detailed Explanation:
Answer: Option 3 — The Rules provide for exact and elaborate criteria for the identification of sites for landfills and waste processing facilities.
Simple Explanation:
The Solid Waste Management (SWM) Rules, 2016 were notified by the Ministry of Environment, Forest and Climate Change (MoEFCC) to improve scientific waste management in India.
The Rules contain detailed provisions regarding the selection of sites for sanitary landfills and waste processing facilities, including distance from rivers, highways, habitations, and airports.
❌ Statement A – Incorrect: Waste generators are required to segregate waste into three categories—Biodegradable (wet), Non-biodegradable (dry), and Domestic Hazardous Waste, not five categories.
❌ Statement B – Incorrect: The Rules apply to a much wider range of areas, including urban local bodies, census towns, railways, airports, ports, SEZs, industrial townships, and pilgrimage sites.
✅ Statement C – Correct: Schedule I of the SWM Rules, 2016 provides detailed criteria for identifying suitable landfill and waste processing sites.
❌ Statement D – Incorrect: The Rules do not prohibit movement of waste across districts. In fact, they encourage regional facilities serving multiple local bodies.
Biological Oxygen Demand (BOD) is a standard criterion for -
Detailed Explanation:
Answer: Option 3 — Pollution assay in aquatic ecosystems
Biological Oxygen Demand (BOD) is a standard criterion for measuring the amount of dissolved oxygen consumed by microorganisms while decomposing organic matter in water bodies. It serves as a key indicator of water pollution—higher BOD values indicate greater organic pollution and potential harm to aquatic life due to oxygen depletion. BOD testing is widely used in environmental monitoring to assess the health and quality of aquatic ecosystems.
In the context of solving pollution problems, what is/are the advantage/advantages of bioremediation technique?
- It is a technique for cleaning up pollution by enhancing the same biodegradation process that occurs in nature.
- Any contaminant with heavy metals such as cadmium and lead can be readily and completely treated by bioremediation using microorganisms.
- Genetic engineering can be used to create microorganisms specifically designed for bioremediation.
Select the correct answer using the code given below:
Detailed Explanation:
Answer: Option 3 — 1 and 3 only
Bioremediation is a pollution control technique that uses living organisms, primarily microorganisms, to degrade or neutralize environmental contaminants by enhancing natural biodegradation processes. While genetic engineering can create specialized microorganisms for targeted bioremediation, heavy metals like cadmium and lead cannot be readily or completely treated through this technique as they are elements that cannot be biodegraded.
✅ Statement 1 – Correct: Bioremediation works by enhancing the natural biodegradation processes that occur in nature, using microorganisms to break down pollutants in soil, water, or other environments.
❌ Statement 2 – Incorrect: Heavy metals like cadmium and lead cannot be readily and completely treated by bioremediation because they are elemental pollutants that cannot be biodegraded, though they may be transformed or immobilized.
✅ Statement 3 – Correct: Genetic engineering techniques can be used to design microorganisms with enhanced or specific capabilities to target particular contaminants for more effective bioremediation.
Consider the following pairs: Commonly used/consumed materials and Unwanted or controversial chemicals likely to be found in them
- Lipstick: Lead
- Soft drinks: Brominated vegetable oils
- Chinese fast food: Monosodium glutamate
Which of the pairs given above is/are correctly matched?
Detailed Explanation:
Answer: Option 4 — 1, 2 and 3
✅ Pair 1 – Correct: Lipstick formulations have been found to contain lead, a heavy metal that poses potential health risks. Studies have detected trace amounts of lead in various lipstick brands, making this a valid concern.
✅ Pair 2 – Correct: Brominated vegetable oils (BVO) are used in some soft drinks as emulsifiers to keep citrus flavoring evenly distributed. BVO has been banned in several countries due to health concerns and potential toxicity.
✅ Pair 3 – Correct: Monosodium glutamate (MSG) is a flavor enhancer commonly used in Chinese fast food and various Asian cuisines. While controversial, MSG is used to enhance savory taste, though its safety remains debated.
All three pairs are correctly matched.