Pollution — REET EVS Notes
This page covers the types of pollution (air, water, soil, noise), their causes, effects, and control measures. In REET EVS, this topic underpins many questions on hygiene and environmental protection, and occasionally throws in a fact-based question on a specific standard or limit.
- 1 question in REET 2024
- Class 1–5 level
- 6 min read
How this topic is asked in REET
REET 2024 asked about noise pollution — specifically, the tolerable noise limit (in dB) considered acceptable in hospital zones. BSER declared this question BONUS in the final answer key, because none of the given options matched either WHO or India's actual noise-pollution regulations. The takeaway: REET does build questions around pollution standards and limits (like decibel limits for noise), so learn them carefully, but don't panic if the options given seem inconsistent or unclear.
Types, Causes and Effects of Pollution
| Type | Main causes | Main effects |
|---|---|---|
| Air pollution | Smoke from vehicles and factories, burning of fossil fuels | Respiratory diseases, global warming, acid rain |
| Water pollution | Industrial waste, sewage, chemical fertilisers/pesticides | Waterborne diseases, death of aquatic life |
| Soil pollution | Plastic waste, pesticides, improper waste disposal | Reduced soil fertility, toxins entering the food chain |
| Noise pollution | Vehicle horns, loudspeakers, industrial machinery | Hearing loss, stress, disturbed sleep |
Under India's Noise Pollution (Regulation and Control) Rules, 2000, silence zones (which include hospitals) are limited to 50 dB during the day and 40 dB at night.[Source 1]
Global Warming vs Ozone Layer Depletion
Greenhouse gases such as carbon dioxide and methane trap heat in the atmosphere and raise Earth's average temperature — this is called global warming. Chlorofluorocarbons (CFCs), on the other hand, damage the ozone layer that shields Earth from the sun's harmful ultraviolet (UV) rays, a process called 'ozone layer depletion'.
These are two separate problems that get confused often — global warming is about rising temperature, while ozone depletion is about a weakening UV shield. In EVS it's essential to clearly separate the gases responsible for each (CO₂/methane vs CFCs).
Internationally, these two problems are addressed by different treaties — the Montreal Protocol (1987) was created to phase out the production and use of ozone-depleting chemicals like CFCs, while the Kyoto Protocol (1997) and later the Paris Agreement (2015) were designed to cut greenhouse gas emissions and curb global warming. REET can sometimes build confusing questions around the names and purposes of these treaties, so it helps to remember the pairing 'Montreal = ozone' and 'Kyoto/Paris = global warming'.
Key Effects Linked to Pollution
- Acid rain
- Sulphur and nitrogen oxide gases combine with water vapour in the atmosphere to form acid rain, which damages buildings, crops and water sources
- Greenhouse effect
- Gases like CO₂, methane and nitrous oxide trap the sun's heat in the atmosphere, raising Earth's temperature
- Eutrophication
- Chemical fertilisers washing into water bodies cause excessive algae growth, which lowers oxygen levels in the water and kills aquatic life
- Bioaccumulation
- Pesticides and chemicals become more concentrated as they move up the food chain, so top consumers (such as humans) are affected the most
- Biological Oxygen Demand (BOD)
- The amount of oxygen microorganisms need to break down organic pollutants in water; the higher the BOD, the more polluted the water is considered to be
Pollution Control Measures
The 3R principle — Reduce, Reuse and Recycle — is considered the most effective approach to controlling pollution. Beyond that, using public transport, planting trees, cutting down plastic use, proper waste disposal (separating dry and wet waste) and regular vehicle emission checks (PUC certificates) all help reduce air and soil pollution.
To prevent water pollution, industrial waste must be treated at a treatment plant before it is released, rather than discharged directly into rivers and drains. In India, the Central Pollution Control Board (CPCB) and state pollution control boards (such as the Rajasthan Pollution Control Board) monitor and enforce pollution standards.
Electronic waste (e-waste) — old mobile phones, computers and batteries — is also a growing source of soil and water pollution, since these contain toxic metals like lead and mercury; they should be deposited at authorised e-waste collection centres rather than thrown out with regular garbage. Similarly, afforestation and expanding urban green belts help reduce both air pollution and noise, since trees absorb dust particles as well as sound.
Cleanliness Campaigns and Community Participation
The Government of India launched the 'Swachh Bharat Abhiyan' in 2014, aimed at ending open defecation, improving solid waste management and promoting public hygiene — this connects directly to pollution control, since proper waste management cuts down both soil and water pollution. At the school level, programmes like 'Swachhata Hi Seva' directly involve children in cleanliness activities.
In a state like Rajasthan, mining and stone-crushing activities also create dust and air pollution problems, particularly in the Aravalli region. EVS teachers can use this to help children understand why development work needs to be balanced with environmental protection.
For quicker resolution of environmental disputes, the Government of India set up the National Green Tribunal (NGT) in 2010, which functions like a special court for cases involving pollution and environmental damage.
How to Teach This to Children
Classroom activity
Run a 'dry waste-wet waste' segregation activity on the school premises, where children sort waste into two bins themselves — this gives them hands-on experience of the 3R principle.
Teaching aids
Show two pictures — one polluted, one clean environment — and ask children to spot the difference, or run a tree-planting activity to explain the role of trees in air purification.
Common misconception
Children often think of 'global warming' and 'ozone layer damage' as the same problem. Teachers should use separate examples and pictures to make the distinction clear.
Assessment idea
Have children list 3 pollution-prevention habits they can adopt at home (such as saving water, using less plastic), and check back a week later to see if they followed through — this is a behaviour-change-based assessment.
Project work
Split children into groups, assign each group one type of pollution (air/water/soil/noise), and have them make a poster and present it in class — this also builds collaborative learning.
Memory trick
If a question about pollution standards (like the noise decibel limit) has options that all seem far off from both WHO and Indian regulations, don't panic — exactly that happened with a REET 2024 question that ended up BONUS. Your better bet is to firmly memorise the 3R principle, the difference between greenhouse gases and CFCs, and the names of bodies like the CPCB, since those facts are almost always tested straightforwardly.
REET 2024 Questions (Solved)
Question 129Bonus — dropped in the final key
How many decibel noise has been accepted to be the limit to tolerance in hospital areas according to International Standards ?
- A65 dB
- B90 dB
- C105 dB
- D140 dB
Explanation
BSER ने अंतिम उत्तर कुंजी में इस प्रश्न को BONUS घोषित किया, अर्थात सभी अभ्यर्थियों को अंक दिए गए; बोर्ड ने कारण नहीं बताया। विश्व स्वास्थ्य संगठन (WHO) के सामुदायिक शोर दिशानिर्देशों में अस्पताल के वार्ड के भीतर लगभग 30 dB (LAeq) की सीमा सुझाई गई है, और भारत के ध्वनि प्रदूषण नियम, 2000 में शान्त क्षेत्र (silence zone) के लिए दिन में 50 dB तथा रात में 40 dB की सीमा है। दिए गए विकल्पों 65, 90, 105 और 140 dB में से कोई भी इन मानकों से मेल नहीं खाता।
Practice Questions
Question 1
Smoke from vehicles and factories mainly causes which type of pollution?
- Aजल प्रदूषण
- Bवायु प्रदूषण
- Cध्वनि प्रदूषण
- Dमृदा प्रदूषण
Explanation
Smoke from vehicles and factories mixes harmful gases and particles into the atmosphere, causing air pollution.
Question 2
Which chemical causes the most damage to the ozone layer?
- Aकार्बन डाइऑक्साइड
- Bमीथेन
- Cक्लोरोफ्लोरोकार्बन (CFC)
- Dनाइट्रोजन
Explanation
Chemicals such as chlorofluorocarbons (CFCs) destroy the ozone layer, while CO₂ and methane are the greenhouse gases mainly responsible for global warming.
Question 3
What is the correct order of the 'R's in the 3R principle?
- AReduce, Reuse, Recycle
- BRecycle, Reduce, Reuse
- CReuse, Recycle, Reduce
- DRecycle, Reuse, Reduce
Explanation
The 3R principle prioritises reducing usage first (Reduce), then reusing (Reuse), and recycling (Recycle) last.
Question 4
Directly discharging industrial waste into a river mainly causes which type of pollution?
- Aध्वनि प्रदूषण
- Bजल प्रदूषण
- Cप्रकाश प्रदूषण
- Dरेडियोधर्मी प्रदूषण केवल
Explanation
Discharging industrial waste and sewage directly into rivers without treatment is a major cause of water pollution.
Question 5
When were the Noise Pollution (Regulation and Control) Rules made in India?
- A1986
- B2000
- C2010
- D2019
Explanation
India's Noise Pollution (Regulation and Control) Rules were made in 2000, setting decibel limits for different types of areas.
Question 6
Improper disposal of plastic waste mainly increases which type of pollution?
- Aमृदा प्रदूषण
- Bध्वनि प्रदूषण
- Cप्रकाश प्रदूषण
- Dरेडियोधर्मी प्रदूषण
Explanation
Plastic waste doesn't break down easily in soil, which is why it drives soil pollution and reduces soil fertility.
Question 7
Which central body is responsible for monitoring and enforcing pollution standards in India?
- Aकेंद्रीय प्रदूषण नियंत्रण बोर्ड (CPCB)
- Bभारतीय रिज़र्व बैंक (RBI)
- Cचुनाव आयोग
- Dनीति आयोग
Explanation
The Central Pollution Control Board (CPCB) is India's leading agency for monitoring and enforcing air, water and noise pollution standards.
Question 8
Which is the most suitable practical activity for teaching children waste management in class?
- Aकेवल परिभाषा श्यामपट्ट पर लिखवाना
- Bस्कूल में सूखा-गीला कचरा अलग करने का अभ्यास करवाना
- Cटॉपिक को छोड़ देना
- Dबच्चों से निबंध याद करवाना
Explanation
Hands-on activity helps children learn the 3R principle through direct experience, which is far more effective than simply memorising a definition.
Question 9
Which certificate is mandatory in India to control air pollution from vehicles?
- APUC प्रमाणपत्र (Pollution Under Control)
- BRC प्रमाणपत्र केवल
- Cबीमा प्रमाणपत्र केवल
- Dपैन कार्ड
Explanation
A PUC (Pollution Under Control) certificate is mandatory in India to keep vehicle emissions within prescribed limits.
Question 10
If loud machines and loudspeakers keep running continuously in an area, which type of pollution will this mainly cause?
- Aजल प्रदूषण
- Bध्वनि प्रदूषण
- Cमृदा प्रदूषण
- Dवायु प्रदूषण केवल
Explanation
Unwanted noise from loud machinery and loudspeakers running continuously is called noise pollution, which affects hearing ability and mental health.
Frequently Asked Questions
How many main types of pollution are there?+
Pollution is mainly of four types — air pollution, water pollution, soil pollution and noise pollution.
What's the difference between global warming and ozone layer depletion?+
Global warming is the problem of Earth's temperature rising because of greenhouse gases like CO₂/methane, while ozone layer depletion is the weakening of the UV-protection shield due to chemicals like CFCs — the two have different causes.
Who sets noise pollution standards in India?+
Under India's Noise Pollution (Regulation and Control) Rules, 2000, different decibel limits are set for silence zones, residential, commercial and industrial areas.
What is the 3R principle?+
3R stands for Reduce, Reuse and Recycle — considered the most effective strategy for pollution and waste control.
What is eutrophication?+
When chemical fertilisers wash into water bodies, they cause excessive algae growth, which lowers oxygen levels in the water and kills aquatic life — this process is called eutrophication.
When did the Swachh Bharat Abhiyan start?+
The Swachh Bharat Abhiyan was launched in 2014, aimed at ending open defecation and promoting proper waste management.
What type of pollution does Biological Oxygen Demand (BOD) measure?+
BOD is a standard for measuring water pollution — it indicates how much oxygen microorganisms need to break down organic pollutants in water; a higher BOD means more polluted water.
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Change Log
- 17 September 2026 — English page published — mirrors the fact-checked Hindi page, independently bilingual-accuracy checked