In the context of permissible noise level match List – I with List – II and select the answer from the code given below the lists.
List – I (Area)
A. Residential area
B. Silent zone
C. Industrial area

Question

In the context of permissible noise level match List – I with List – II and select the answer from the code given below the lists.
List – I (Area)
A. Residential area
B. Silent zone
C. Industrial area
D. Commercial area
List – II (Permissible Noise Level)
1. 50 db
2. 55 db
3. 65 db
4. 70 db
Code :

UnlockIAS · Accepted Answer

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.

Why the other options are wrong — (a) 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) 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) 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).

Concept: 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.

State PCS 2022 Q30 — Environment & Ecology PYQ with Answer

State PCS 2022 Q30 — Environment & Ecology PYQ with Answer