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English · हिन्दी · తెలుగు · தமிழ் · മലയാളം · मराठी · ಕನ್ನಡ

Pollution: quick recap

தமிழில் விளக்கம்

Pollution · Quick recap · Fact-checked on · how we check

Written with AI from the sources listed at the bottom of this page, then fact-checked by a separate AI.

The whole chapter in one sitting: air pollutants, smog, acid rain and India's air standards and programmes; water quality, toxics, river cleaning, soil and noise; and the waste rules with extended producer responsibility.

Each idea is explained first in Tamil (தமிழ்), ending with the English and Hindi exam terms, followed by the same point in exam English. UPSC Prelims is in English or Hindi, so understand it in Tamil and revise it in English.

முதல் பகுதி காற்று பற்றியது. சில நஞ்சுகள் நேரடியாகப் புகைபோக்கியிலிருந்து வருகின்றன, ஓசோன் போன்றவை வெயிலில் காற்றிலேயே உருவாகின்றன. மிக நுண்ணிய தூசி நுரையீரலின் ஆழம் வரை செல்கிறது. குளிர்காலத்தில் காற்று அசையாமல், மேலே உள்ள வெப்ப அடுக்கு மூடி போட்டது போலப் புகையைக் கீழேயே அடைக்கிறது. லண்டன் புகைமூட்டம் நிலக்கரியுடையது, லாஸ் ஏஞ்சலஸ் புகைமூட்டம் வாகனங்களுடையது. அமில மழை தாஜ்மஹால் கல்லைத் தின்பதால் நீதிமன்றம் அதைச் சுற்றி தனி மண்டலம் வைத்தது. (→ English: primary and secondary pollutants; particulate matter; temperature inversion; smog; acid rain; Taj Trapezium Zone · हिन्दी: प्राथमिक और द्वितीयक प्रदूषक; कणिकीय पदार्थ; तापमान व्युत्क्रमण; धूम-कोहरा; अम्लीय वर्षा; ताज ट्रेपेज़ियम ज़ोन)

In exam EnglishPollution is the addition of a substance or form of energy to air, water or soil in amounts that harm life or property. In air, primary pollutants such as sulphur dioxide and carbon monoxide leave their source already harmful, while secondary pollutants such as ground-level ozone form in the air itself. Fine particles (PM2.5) do the most damage to health. In winter, crop-residue smoke, calm air and temperature inversion trap pollution over the northern plains. Classical smog (London, 1952) is cold, coal-based and reducing; photochemical smog is sunny, traffic-based and oxidising. Acid rain, with a pH below 5.6, comes from sulphur dioxide and nitrogen oxides; in 1996 the Supreme Court protected the Taj Mahal through the Taj Trapezium Zone.

காற்றை அளக்க 2009 தரநிலைகள், தினமும் சொல்லக் காற்றுத் தரக் குறியீடு. குறியீட்டில் எட்டு நஞ்சுகளில் எது மிக மோசமோ அதுவே அன்றைய எண், வகுப்பில் மிகக் குறைந்த மதிப்பெண்ணே மொத்த வகுப்பின் மதிப்பெண் என்பது போல. டெல்லியில் குறியீடு மோசமாகும்போது கட்டுப்பாடுகள் படிப்படியாகக் கூடுகின்றன. CNG பேருந்து, BS-VI வாகனம், எத்தனால், சமையல் எரிவாயு காற்றைச் சுத்தமாக்கும் வழிகள். (→ English: National Ambient Air Quality Standards; National Air Quality Index; NCAP; GRAP; Commission for Air Quality Management; Bharat Stage VI · हिन्दी: राष्ट्रीय परिवेशी वायु गुणवत्ता मानक; राष्ट्रीय वायु गुणवत्ता सूचकांक; NCAP; GRAP; वायु गुणवत्ता प्रबंधन आयोग; भारत स्टेज VI)

In exam EnglishIndia measures air against the National Ambient Air Quality Standards of 2009, which cover 12 pollutants and set PM2.5 limits of 40 micrograms per cubic metre a year and 60 over 24 hours, far above the WHO guideline of 5 adopted in 2021. The National Air Quality Index (2014) uses eight pollutants and six categories, and the worst sub-index decides the reading. The National Clean Air Programme (2019) set reduction targets for cities that miss the standards. For Delhi and its region, the Graded Response Action Plan (2017) adds curbs stage by stage as the index worsens, and since 2021 the Commission for Air Quality Management runs it. Cleaner fuels did the rest: CNG for Delhi's buses (1998), the jump to Bharat Stage VI vehicles on 1 April 2020, ethanol blending and clean cooking gas.

நீரை ஆக்சிஜனால் அளக்கிறார்கள். கழிவுநீர் அதிகமானால் பாக்டீரியா ஆக்சிஜன் முழுவதையும் தின்றுவிடும்; அதுவே உயிர்வேதி ஆக்சிஜன் தேவை கூடுவது, மீன்களுக்கு மூச்சுத் திணறல். உரங்கள் பாசியைப் பெருக்குகின்றன, பாசி அழுகிக் குளத்தைக் கொல்கிறது. பாதரசம், காட்மியம், ஆர்சனிக், புளோரைடு போன்றவை அழுகாது, உடலில் சேரும், கடன் மேல் வட்டி போல. கழிவுநீர் சுத்திகரிப்பு, நதித் திட்டங்கள், பாக்டீரியா, செடிகள் சுத்தம் செய்யும் வழிகள். (→ English: dissolved oxygen; biochemical oxygen demand; eutrophication; Minamata and itai-itai disease; arsenic and fluoride; biomagnification; Namami Gange · हिन्दी: घुलित ऑक्सीजन; जैव-रासायनिक ऑक्सीजन माँग; सुपोषण; मिनामाता और इताई-इताई रोग; आर्सेनिक और फ़्लोराइड; जैव आवर्धन; नमामि गंगे)

In exam EnglishWater quality is read through oxygen. Dissolved oxygen is what aquatic life breathes; biochemical oxygen demand is the oxygen microbes use to break down organic matter, so sewage pushes BOD up and DO down, and chemical oxygen demand is normally higher than BOD. In eutrophication, nitrogen and phosphorus feed algal blooms whose decay strips the water of oxygen. Toxic substances are a separate danger because they persist: mercury caused Minamata disease and cadmium itai-itai disease in Japan, natural arsenic poisons wells in the Ganga-Brahmaputra plains, excess fluoride causes fluorosis and nitrate causes blue baby syndrome. Persistent pesticides such as DDT accumulate in bodies and magnify up food chains. Remedies range from sewage treatment and river missions (Ganga Action Plan 1985, Namami Gange 2015) to clean-up by microbes and plants.

ஒலி டெசிபலில்; 10 கூடினால் ஆற்றல் பத்து மடங்கு, படி அல்ல மாடி ஏறுவது போல. பகலுக்கும் இரவுக்கும் தனி வரம்பு; மருத்துவமனை, பள்ளி, நீதிமன்றம் சுற்றி 100 மீட்டர் அமைதி மண்டலம். இரவு 10 முதல் காலை 6 வரை வெளியே ஒலிபெருக்கி கூடாது. சூடான நீர் மீன்களின் ஆக்சிஜனைக் குறைக்கிறது, அதிக வெளிச்சம் இரவு உயிரினங்களை வழி தவறச் செய்கிறது, சிந்திய எண்ணெய் பறவைகளின் இறகுகளை ஒட்டவைக்கிறது. (→ English: decibel; Noise Pollution (Regulation and Control) Rules, 2000; silence zone; thermal, radioactive and light pollution · हिन्दी: डेसिबल; ध्वनि प्रदूषण (विनियमन और नियंत्रण) नियम, 2000; शांत क्षेत्र; तापीय, रेडियोधर्मी और प्रकाश प्रदूषण)

In exam EnglishNoise is measured in decibels on a logarithmic scale, so every 10 dB rise means ten times the sound energy. The Noise Pollution (Regulation and Control) Rules, 2000, made under the Environment (Protection) Act, set day and night limits for industrial, commercial and residential areas and for the silence zone, the belt of 100 metres or more that surrounds a hospital, an educational institution or a court. Loudspeakers are barred at night, from 10 p.m. to 6 a.m., outside closed premises, and in 2005 the Supreme Court tied freedom from noise to Article 21. Thermal pollution lowers the oxygen in water, radioactive pollution damages cells and genes, light pollution misleads night-active animals, and oil spills smother the sea surface and seabirds.

கழிவு விதிகள் எல்லாம் ஒரு குடும்பம். வீட்டில் மூன்று தொட்டிகள்: ஈரம், உலர், அபாயம்; பிறகு நகராட்சி எடுத்துச் சுத்திகரிக்க வேண்டும், கடைசி மிச்சம் மட்டும் குழிக்கு. பாக்கெட், போன், பேட்டரிக்கு நீட்டிக்கப்பட்ட உற்பத்தியாளர் பொறுப்பு: விற்றவரே திரும்ப எடுக்க வேண்டும். மருத்துவமனைக் கழிவுக்கு நான்கு வண்ணத் தொட்டிகள், தொழிற்சாலை நஞ்சுக்குத் தொழிற்சாலை, இடிபாடுகளுக்குக் கட்டுபவர் பொறுப்பு. (→ English: Solid Waste Management Rules, 2016; extended producer responsibility; single-use plastic; bio-medical waste; hazardous waste · हिन्दी: ठोस अपशिष्ट प्रबंधन नियम, 2016; विस्तारित उत्पादक उत्तरदायित्व; एकल-उपयोग प्लास्टिक; जैव-चिकित्सा अपशिष्ट; परिसंकटमय अपशिष्ट)

In exam EnglishWaste is handled by a family of rules made under the Environment (Protection) Act, most of them from 2016. The Solid Waste Management Rules make households segregate waste into wet, dry and domestic hazardous streams and make local bodies collect and process it, so that only inert residue reaches a sanitary landfill. For packaging, electronics and batteries the rules use extended producer responsibility: producers must collect or recycle what they sell and prove it with certificates. Plastic carry bags rose from 50 to 75 and then 120 microns, and identified single-use plastic items were banned from 1 July 2022. Bio-medical waste is sorted into yellow, red, white and blue containers; industrial hazardous waste is the factory occupier's duty; batteries, including electric-vehicle ones, have their own 2022 rules, and building debris is the builder's responsibility.
Pollution at a glance
PartCore ideasLaws, bodies and dates
1. AirPrimary and secondary pollutants, PM2.5, smog, acid rain, winter inversionNAAQS 2009; AQI 2014; NCAP 2019; GRAP 2017; CAQM 2021; BS-VI 2020; Taj Trapezium 1996
2. Water, soil, noiseDO, BOD, COD; eutrophication; heavy metals, arsenic, fluoride, nitrate; biomagnification; decibelsGanga Action Plan 1985; Namami Gange 2015; endosulfan ban 2011; Noise Rules 2000; Supreme Court 2005
3. WasteSegregation at source; processing before landfill; extended producer responsibilitySWM, Plastic, Bio-Medical, Hazardous and C&D Rules 2016; single-use plastic ban 2022; E-Waste and Battery Rules 2022

Exam traps

Recap

Practice questions

Q1. Photochemical smog differs from classical smog mainly because it:

  1. forms in cold, damp weather from coal smoke
  2. forms in sunny weather from nitrogen oxides and hydrocarbons and is oxidising
  3. contains mainly sulphuric acid droplets
  4. occurred first in London in 1952
Show answer

Answer: B. forms in sunny weather from nitrogen oxides and hydrocarbons and is oxidising

Photochemical smog needs sunlight acting on traffic gases and is oxidising. Cold damp weather with coal smoke, sulphuric acid droplets and the London episode of 1952 all describe classical smog, so options 1, 3 and 4 are wrong.

Q2. Consider the following statements about the National Air Quality Index:
1. It was launched in 2014.
2. The overall index is the average of the sub-indices of all pollutants measured.
Which of the statements given above is/are correct?

  1. 1 only
  2. 2 only
  3. Both 1 and 2
  4. Neither 1 nor 2
Show answer

Answer: A. 1 only

Statement 1 is correct, so option 4 is wrong. Statement 2 is wrong because the worst sub-index, not the average, decides the overall index, so options 2 and 3 are wrong.

Q3. Which one of the following statements about water quality is correct?

  1. A higher BOD indicates cleaner water
  2. COD of a sample is normally higher than its BOD
  3. Warm water holds more dissolved oxygen than cold water
  4. Eutrophication increases dissolved oxygen in the long run
Show answer

Answer: B. COD of a sample is normally higher than its BOD

COD also counts matter microbes cannot digest, so it is normally above BOD. A higher BOD means more organic pollution; warm water holds less oxygen, which is why thermal pollution harms fish; and eutrophication lowers oxygen as dead algae decay, so options 1, 3 and 4 are wrong.

Q4. Consider the following pairs:
1. Minamata disease : Mercury
2. Fluorosis : Arsenic
3. Blue baby syndrome : Nitrate
Which of the pairs given above are correctly matched?

  1. 1 and 2 only
  2. 2 and 3 only
  3. 1 and 3 only
  4. 1, 2 and 3
Show answer

Answer: C. 1 and 3 only

Pairs 1 and 3 are correct. Pair 2 is wrong because fluorosis is caused by excess fluoride; arsenic causes skin lesions and cancers. So options 1, 2 and 4, which include pair 2, are wrong.

Q5. Consider the following statements:
1. Namami Gange was approved by the Union government in 2015.
2. The Ganga Action Plan was launched after Namami Gange, in 2018.
Which of the statements given above is/are correct?

  1. 1 only
  2. 2 only
  3. Both 1 and 2
  4. Neither 1 nor 2
Show answer

Answer: A. 1 only

Statement 1 is correct, so option 4 is wrong. Statement 2 is wrong because the Ganga Action Plan came much earlier, in 1985, so options 2 and 3 are wrong.

Q6. Under the Noise Pollution (Regulation and Control) Rules, 2000, a silence zone is an area of at least 100 metres around:

  1. hospitals, educational institutions and courts
  2. airports and railway stations
  3. industrial estates
  4. national parks and sanctuaries
Show answer

Answer: A. hospitals, educational institutions and courts

The Rules define a silence zone around hospitals, educational institutions and courts. Airports, railway stations and industrial estates are noisy areas, not silence zones, and national parks are protected under wildlife law rather than declared silence zones by these Rules, so options 2, 3 and 4 are wrong.

Q7. Consider the following statements:
1. Under the Solid Waste Management Rules, 2016, households must segregate waste into three streams.
2. Extended producer responsibility applies to plastic packaging, e-waste and batteries.
3. The single-use plastic ban of 2022 prohibits all plastic packaging.
Which of the statements given above are correct?

  1. 1 and 2 only
  2. 2 and 3 only
  3. 1 and 3 only
  4. 1, 2 and 3
Show answer

Answer: A. 1 and 2 only

Statements 1 and 2 are correct. Statement 3 is wrong: the ban covers a list of identified items, while packaging is managed through EPR, so options 2, 3 and 4, which include statement 3, are wrong.

Q8. Under the Bio-Medical Waste Management Rules, 2016, which colour of container is meant for glassware and metallic body implants?

  1. Yellow
  2. Red
  3. White (translucent)
  4. Blue
Show answer

Answer: D. Blue

Glassware and metallic implants go in blue. Yellow is for body parts, soiled dressings and discarded medicines; red for contaminated recyclable plastic items; white for sharps such as needles and blades.

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