Public laws, 89th Congress. 675. S. 3112, act to amend Clean air act so as to authorize grants to air pollution control agencies for maintenance of air pollution control programs in addition to present authority for grants to develop, establish, or Improve such programs, make use of appropriations under act more flexible y consolidating appropriation authorizations under act and deleting provision limiting total of grants for support of air pollution control programs to 20 per centum of total appropriation for any year, extend duration of programs authorized by act and for other purposes.