law: Air (Prevention and Control of Pollution) Act, 1981
  2. Definitions.
  
  
  In this Act, unless the context otherwise requires,-
  (a)
  
  "air pollution" means any solid, liquid or gaseous substance [ 2
  
  (including noise) 2 ] present in the atmosphere in such concentration as may be
  
  or tend to be injurious to human beings or other living creatures or plants or
  
  property or environment;
  (b)
  
  "air pollution" means the presence in the atmosphere of any air
  
  pollutant;
  (c)
  
  "approved appliance" means any equipment or gadget used for the
  
  burning of any combustible material or for generating or consuming any fume,
  
  gas or particulate matter and approved by the State Board for the purposes of
  
  this Act;
  (d)
  
  "approved fuel" means any fuel approved by the State Board for the
  
  purposes of this Act;
  (e)
  
  "automobile" means any vehicle powered either by internal combustion
  
  engine or by any method of generating power to drive such vehicle by burning
  
  fuel;
  (f)
  
  "Board" means the Central Board or a State Board;
  (g)
  
  "Central Board" means the [ 3 Central Pollution Control Board 3 ]
  
  constituted under Section 3 of the Water (Prevention and Control of Pollution)
  
  Act, 1974 (6 of 1974);
  (h)
  
  "chimney" includes any structure with an opening or outlet from or
  
  through which any air pollutant may be emitted;
  (i)
  
  "control equipment" means any apparatus, device, equipment or system
  
  to control the quality and manner of emission of any air pollutant and includes
  
  any device used for securing the efficient operation of any industrial plant;
  
  
  (j) "emission" means any solid or liquid or gaseous substance coming
  
  out of any chimney, duct or flue or any other outlet;
  (k)
  
  "industrial plant" means any plant used for any industrial or trade
  
  purposes and emitting any air pollutant into the atmosphere;
  (l)
  
  "member" means a member of the Central Board or a State Board, as the
  
  case may be, and includes the Chairman thereof;
  [
  
  4 (m) "occupier", in relation to any factory or premises, means the
  
  person who has control over the affairs of the factory or the premises, and
  
  includes, in relation to any substance, the person in possession of the
  
  substance; 4 ]
  (n)
  
  "prescribed" means prescribed by rules made under this Act by the
  
  Central Government or, as the case may be, the State Government;
  (o)
  
  "State Board" means, -
  (i) in relation to a State in which the Water (Prevention
  
  and Control of Pollution) Act, 1974 (6 of 1974), is in force and the State
  
  Government has constituted for that State [ 4 State Pollution Control Board 4 ]
  
  under Section 4 of that Act, the said State Board; and
  Comments:
  
  "We have therefore reflected over the various aspects of this rather
  
  difficult and complex question with great anxiety and care and taking an
  
  overall view of the diverse considerations we have, with considerable
  
  hesitation, bordering almost on trepidations reached the conclusion that,
  
  pending consideration of the issue whether the caustic chlorine plant should be
  
  directed to be shifted and relocated at some other place, the caustic chlorine
  
  plant should be allowed to be restarted by the management of Shriram, subject
  
  to certain stringent conditions which we propose to specify"  M. C.
  
  Mehta v. Union of India. AIR 1987 SUPREME COURT 965