Noise pollution

Topic: Geographical Issues: Pollution, Urban Waste, Slums and Land Degradation · NCERT: Class 10, Ch 6 "Manufacturing Industries"; Class 12, Ch 9 "Geographical Perspective on Selected Issues and Problems"

Meaning

Noise pollution is unwanted sound that people find unbearable and uncomfortable. It comes from sources such as factories, construction, vehicles, aircraft, trains, sirens and loudspeakers, and it is measured in decibels (dB). It matters because it harms health, causing hearing loss, high blood pressure, heart disease and poor sleep. It is worst in metro cities, where traffic, construction and crowds all come together.

Explanation

How noise is measured

• The unit is the decibel (dB).
• This is a logarithmic scale, not a straight-line scale.
• Each rise of 10 dB means the sound is ten times more intense.

• So 70 dB is not "a little more" than 60 dB. It is ten times stronger.

• dB(A) means "A-weighted" sound. The reading is adjusted to match how the human ear hears [2].

• Leq (equivalent continuous sound level) is the average sound energy over a set period, such as a whole day or night [2].
• Indian legal limits are given in dB(A) Leq [2].

Sources of noise

Source type	Examples	Key point
Industrial	Factories, mines	Noise level depends on the type of industry
Construction	Building and demolition machines	Heavy, irregular noise from machines
Transport	Road vehicles, aircraft, trains	The biggest nuisance (NCERT)
Periodic / social	Sirens, loudspeakers at festivals and community events	Short bursts, but very loud
Sea	Ships loading and unloading	Stays inside harbours

• Why traffic noise varies:
• It depends on the type of aircraft, vehicle or train.
• It depends on the road. Bad roads mean more braking and rattling.

• It depends on the vehicle. Old engines and poor silencers are louder.

• Why it is a recent problem:

• New technology brought machines, motor vehicles and aircraft into daily life.
• So noise became a serious concern only recently.

Spatial pattern: noise is location-specific

• Noise is loudest near its source.
• It gets weaker the further you go from the source.

• So it does not spread over a whole region the way polluted air or water can.

• Hotspots: industrial areas, transport arteries (highways and railway lines) and airports.

• Metros are the worst hit. Traffic, construction and crowds all meet in one place.

Health effects and legal limits

• Hearing loss: too much noise damages the hair cells in the cochlea (the snail-shaped hearing organ in the inner ear) [6].
• Heart and stress:
• Long-term exposure to traffic noise is linked to heart disease, stroke and heart failure [6].

• It also raises heart rate and blood pressure.

• Other harms named by WHO: disturbed sleep, poorer work and school performance, and tinnitus (ringing in the ears) [5][6].

• WHO guidance values [6]:
• below 30 dB(A) inside bedrooms at night
• below 35 dB(A) in classrooms

• below 40 dB(A) yearly night average outside bedrooms

• Indian law: Noise Pollution (Regulation and Control) Rules, 2000

• Made under the Environment (Protection) Act, 1986 and notified on 14 February 2000 (S.O. 123(E)) [3].
• Day is 6 am to 10 pm. Night is 10 pm to 6 am [2].

Zone	Day limit dB(A) Leq	Night limit dB(A) Leq
Industrial	75	70
Commercial	65	55
Residential	55	45
Silence zone (at least 100 m around hospitals, schools and courts)	50	40

• The order from strictest to least strict is silence zone, then residential, then commercial, then industrial.
• In every zone, the night limit is 5 to 10 dB lower than the day limit.

Where it occurs

• Industrial noise in India: NCERT Fig. 9.2 shows noise being monitored at the Panchpatmali bauxite mine. It is in Koraput district, Odisha, on the Eastern Ghats. Blasting, drilling and heavy earth-movers make mines high-noise zones.
• Transport corridors: highways, railway lines and areas around airports. At sea, ship noise stays inside harbours.
• Metro cities and CPCB monitoring:
• The National Ambient Noise Monitoring Network (NANMN) has 70 stations in 7 metro cities: Bengaluru, Chennai, Delhi, Hyderabad, Kolkata, Lucknow and Mumbai. Each city has 10 stations [4].
• Phase I (2011): 35 stations, 5 in each city [4].
• Phase II (2015): 35 more stations [4].

• The stations cover all four zone types: silence, residential, commercial and industrial [4].

• Festival checks: the Central and State Pollution Control Boards carry out special noise checks during festivals, mainly Deepawali [2].

• Enforcement: the Noise Rules apply across India. Each State or UT must name an "Authority" to keep noise within the limits [2].
• Supreme Court, In re Noise Pollution (2005): loudspeakers and public address systems are banned from 10 pm to 6 am. The only exception is a relaxation that the government has formally notified.

Don't confuse with

• Sound vs noise pollution: all noise is sound, but noise pollution is only sound that is unwanted, unbearable or uncomfortable. Loudness alone does not decide it. The setting and the listener also matter.
• dB vs dB(A) Leq: a plain dB is just the sound level on a log scale. dB(A) Leq is adjusted to the human ear and averaged over a set time. Indian legal limits use dB(A) Leq [2].
• Silence zone vs residential zone: the silence zone (100 m around hospitals, schools and courts) has the strictest limits at 50 by day and 40 by night. The residential zone allows 55 by day and 45 by night.
• Noise pollution vs air pollution: air pollution leaves material in the air that spreads widely and stays. Noise is location-specific. It fades with distance and stops when the source stops.

Prelims Hooks

• The decibel scale is logarithmic: +10 dB means ten times the sound intensity. Indian standards use dB(A) Leq.
• The Noise Rules, 2000 were made under the Environment (Protection) Act, 1986, not under the Air Act. They were notified on 14 February 2000 [3].
• Zone limits (day/night, dB(A)): industrial 75/70, commercial 65/55, residential 55/45, silence 50/40. The silence zone covers 100 m around hospitals, schools and courts.
• Night time is 10 pm to 6 am under the Rules [2]. The Supreme Court banned loudspeakers in this window in 2005.
• NANMN has 70 stations in 7 metros, with Phase I in 2011 and Phase II in 2015 [4]. Trap: Lucknow is included, but Ahmedabad and Pune are not.
• NCERT names traffic as the biggest source of noise nuisance. The Panchpatmali bauxite mine (Koraput, Odisha) is its example of industrial noise monitoring.

Mains Points

• Urban noise is a planning problem (GS-I):
• Noise is location-specific and gathers along highways, near airports and in industrial belts.
• So it can be fixed through land-use zoning, such as buffer zones near airports and silence zones near hospitals and schools.

• Better roads, well-kept vehicles and enforcement by the authority each State must name also help [2].

• Noise is a public health issue, not just a nuisance (GS-III):

• WHO links it to hearing loss, heart disease, stroke, poor sleep and weaker school performance [5][6].

• This supports adding noise to city clean-air and Smart City plans, and extending monitoring beyond the 7 NANMN metros [4].

• The enforcement gap:

• The 2000 Rules and the 2005 Supreme Court ban on loudspeakers at night are already in place.
• The problem is that they are not followed, especially during festivals, construction and peak traffic.
• Possible fixes are regular monitoring, as the festival-time checks during Deepawali already do [2], public awareness, and stricter penalties for breaking the rules.

Related concepts

• Noise pollution standards
• Land pollution

Read more

• Noise pollution and land pollution