[Power to issue guidelines.21A. (1) Notwithstanding anything contained in this Act, the Central Government in consultation with the Central Board, may, by notification in the Official Gazette, issue guidelines on the matters relating to the grant, refusal or cancellation of consent by any State Board to establish or operate any industrial plant in an air pollution control area, including the mechanism for time bound disposal of the application made under section 21 or validity period of such consent.(2) Every State Board, in discharge of its functions for the purposes of grant, refusal or cancellation of consent under section 21 shall act in accordance with the guidelines issued under sub-section (1).]