(see rule 3(l) and 4(l)
Ambient Air Quality Standards in respect of Noise
Area Code Category of Area/Zone Limits in dB(A) Leq *
Day Time NightTime
(A) Industrial area 75 70
(B) Commercial area 65 55
(C) Residential area 55 45
(D) Silence Zone 50 40
1. Day time shall mean from 6.00 a.m. to 10.00 p.m.
2. Night time shall mean from 10.00 p.m. to 6.00 a.m.
3. Silence zone is defined as an area comprising not less than 100 metres around hospitals, educational institutions and courts. The silence zones are zones which are declared as such by the competent authority.
4. Mixed categories of areas may be declared as one of the four above mentioned categories by the competent authority.
*dB(A) Leq denotes the time weighted average of the level of sound in decibels on scale A which is relatable to human hearing.
A "decibel" is a unit in which noise is measured.
"A", in dB(A) Leq, denotes the frequency weighting in the measurement of noise and corresponds to frequency response characteristics of the human ear.
Leq : It is an energy mean of the noise level, over a specified period.
[F. No. Q-14012/l/96-CPA]
VIJAI SHARMA, R. Secy.