law: Air (Prevention and Control of Pollution) Act, 1981
  18. Power to give Directions.
  In
  
  the performance of its functions under this Act -
  (a)
  
  the Central Board shall be bound by such directions in writing as the Central
  
  Government may give to it; and
  (b)
  
  every State Board shall be bound by such directions in writing as the Central
  
  Board or the State Government may give to it :
  Provided that
  
  where a direction given by the State Government is inconsistent with the
  
  direction given by the Central Board, the matter shall be referred to the
  
  Central Government for its decision.
  (11)
  
  (2) Where the Central Government is of the opinion that any State Board has
  
  defaulted in complying with any directions given by the Central Board under
  
  sub-section (1) and as a result of such default a grave emergency has arisen
  
  and it is necessary or expedient so to do in the public interest, it may, by
  
  order, direct the Central Board to perform any of the functions of the State
  
  Board in relation to such area, for such period and for such purposes, as may
  
  be specified in the order.
  (3)
  
  Where the Central Board performs any of the functions of the State Board in
  
  pursuance of a direction under sub-section (2), the expresses, if any, incurred
  
  by the Central Board with respect to the performance of such functions may, if
  
  the State Board is empowered to recover such expenses, be recovered by the
  
  Central Board with interest (at such reasonable rate as the Central Government
  
  may, by order, fix) from the date when a demand for such expenses is made until
  
  it is paid from the person or persons concerned as arrears of land revenue or
  
  of public demand.