UPPSC 2022 Prelims GS Paper-I · Question 30 of 150

Correct — D, A-2, B-1, C-4, D-3. Residential 55 dB, silent zone 50 dB, industrial 70 dB, commercial 65 dB. The governing standard is the Schedule to the Noise Pollution (Regulation and Control) Rules, 2000, which sets ambient air-quality standards for noise in dB(A) Leq separately for day and night. Three of the four pairings here are the DAYTIME limits: residential 55, silence zone 50, commercial 65. The fourth is not. The daytime limit for an industrial area is 75 dB(A), and 75 does not appear anywhere in List-II; the 70 dB the key pairs with 'Industrial area' is the NIGHT-time limit. The paper therefore mixes the two columns of the same table, and a student should know that plainly rather than carry away '70 dB is the industrial standard'. The matching still works and (d) is still the only defensible code, because the ranking of the four areas is identical in both columns — industrial above commercial above residential above silence zone — so no other pairing of these figures can be built. Day time under the Rules runs from 6 a.m. to 10 p.m. and night time from 10 p.m. to 6 a.m.

• (a)A-3, B-4, C-2, D-1 — Inverted throughout. It gives a residential area 65 dB and a silence zone 70 dB — the two quietest categories awarded the two loudest figures — while allowing an industrial area only 55 dB and a commercial area 50. The whole logic of the Schedule is that permitted noise rises with the intensity of activity, and this option runs it backwards.
• (b)A-1, B-2, C-3, D-4 — It gets the direction right but swaps within both pairs. Residential is given 50 and the silence zone 55, when the silence zone must be the quieter of the two; and industrial is given 65 while commercial gets 70, when industrial is the higher. It is also the run-of-the-mill A-1, B-2, C-3, D-4 sequence that these papers plant as a lazy default.
• (c)A-2, B-1, C-3, D-4 — The near miss, and the only one that needs thinking about. It gets residential 55 and silence zone 50 exactly right, then swaps the last two — industrial 65 and commercial 70. That is the wrong way round: the Schedule permits more noise in an industrial area than in a commercial one, in both the day and the night column. Fix that single swap and you have option (d).

The Noise Pollution (Regulation and Control) Rules, 2000, made under the Environment (Protection) Act, 1986, divide urban space into four categories and set an ambient noise limit for each, measured in dB(A) Leq — an A-weighted, time-averaged decibel level that approximates how the human ear responds. The limits fall as the expected human use becomes more sensitive: industrial 75 by day and 70 by night, commercial 65 and 55, residential 55 and 45, and silence zones 50 and 40. A silence zone is an area of not less than 100 metres around hospitals, educational institutions and courts, declared as such by the competent authority. Because the decibel scale is logarithmic, these apparently small gaps are large: a 10 dB rise is roughly a doubling of perceived loudness.

Never memorise these as eight loose numbers. Memorise the ladder — industrial, commercial, residential, silence zone, in that descending order — and one anchor value, and the rest follows. That ladder alone kills options (a), (b) and (c) here, because each of them breaks it somewhere. The second habit worth building is to ask which column a figure comes from: this question's own List-II quietly mixes daytime figures with a night-time one, and a candidate who has learnt the table as a day/night pair spots that instead of being confused by it. Note that these are ambient standards for an area, not limits on a single source such as a horn, a generator or a loudspeaker, which the same Rules regulate separately.

• Noise Pollution (Regulation and Control) Rules, 2000, framed under the Environment (Protection) Act, 1986
• Ambient standards in dB(A) Leq, day / night — Industrial 75/70, Commercial 65/55, Residential 55/45, Silence Zone 50/40
• Day time is 6 a.m. to 10 p.m.; night time is 10 p.m. to 6 a.m.
• A silence zone is an area of at least 100 metres around hospitals, educational institutions and courts, so declared by the competent authority
• This question's 70 dB for an industrial area is the night-time limit; the daytime industrial limit, 75 dB(A), does not appear in List-II at all

• Quoting 70 dB as 'the' industrial standard — it is the night limit; the daytime limit is 75 dB(A)
• Placing the commercial limit above the industrial one; the Schedule permits the most noise in industrial areas
• Forgetting that a silence zone is defined by a 100-metre radius around hospitals, schools and courts, not by being merely residential

UPPSC asks this as a four-way match of area to decibel figure, and also asks the parent statutes by year — the Environment (Protection) Act 1986, the Water Act 1974. UPSC has approached noise from the physics and measurement side instead, asking what a given decibel level corresponds to in daily life, so prepare both the legal table and a feel for the scale.

• practice — not a real PYQ

  Under the Noise Pollution (Regulation and Control) Rules, 2000, a 'silence zone' is an area of not less than how much distance around hospitals, educational institutions and courts?

  • (a)50 metres
  • (b)100 metres
  • (c)200 metres
  • (d)500 metres

  Answer(b) 100 metres — the area so declared by the competent authority carries the strictest ambient limits, 50 dB(A) by day and 40 dB(A) by night.

• practice — not a real PYQ

  The Noise Pollution (Regulation and Control) Rules, 2000 were framed under which parent legislation?

  • (a)The Air (Prevention and Control of Pollution) Act, 1981
  • (b)The Factories Act, 1948
  • (c)The Environment (Protection) Act, 1986
  • (d)The National Green Tribunal Act, 2010

  Answer(c) The Environment (Protection) Act, 1986 — the umbrella statute under which most of India's environmental rules, including the noise standards, are notified.