Arizona Revised Statutes Title 49. The Environment § 49-473. Board of supervisors

A. The board of supervisors of a county, in order to conserve and promote the public health, safety, and general welfare, shall within its territorial limits, or any portion thereof, investigate the degree to which the atmosphere of the county is contaminated by air pollution and the causes, sources, and extent of such air pollution or, if the state is developing a study in the county pursuant to § 49-424, cooperate with and assist the state in such a study.

B. The board of supervisors of a county shall authorize or designate an existing department of the county government or establish an air pollution control district to carry out the necessary investigations, inspections, and enforcement of any rules and regulations adopted pursuant to this article.

C. The board of supervisors of a county may in lieu of the provisions of subsection B, in addition to the joint exercise of powers provided for in title 11, chapter 7, article 3,  1 establish a multi-county air quality control region with one or more other counties by agreement with the board of supervisors of such other county or counties, and contract for the joint administration of this article within such region, including, but not limited to, the joint adoption of regulations and standards and the enforcement thereof by a joint region hearing board. Any region created under this subsection shall be governed by all of the provisions applicable to a county.