Sec. 116.  Except as  otherwise provided  in sections 119  (c),
(e), and (f)(as in effect before the date of the enactment of the
Clean  Air  Act  Amendments  of 1977),  209,  211(c)(4),  and 233
(preempting certain State regulation  of moving sources)  nothing
in  this Act  shall preclude or  deny the  right of  any State or
political  subdivision  thereof  to  adopt  or  enforce  (1)  any
standard or limitation respecting  emissions of air pollutants or
(2)  any  requirement  respecting  control or  abatement  of  air
pollution;  except that if an emission  standard or limitation is
in  effect  under  an  applicable implementation  plan  or  under
section 111 or 112,  such State or political subdivision  may not
adopt or  enforce any  emission standard  or limitation  which is
less stringent than the standard or limitation under such plan or
section.
[42 U.S.C. 7416]