17.16.050   Visibility limiting standard.
   A.   No person shall cause, suffer, allow or permit operations or activities likely to result in excessive amounts of airborne dust without taking reasonable precautions to prevent excessive amounts of particulate matter from becoming airborne.
   B.   Except for sources located within the boundaries of the Tohono O'Odham, Pasqua Yaqui and San Xavier Indian Reservations, opacity of an emission from any nonpoint source, as measured in accordance with the Arizona Testing Manual, Reference Method 9, shall not exceed the following:
      1.   Twenty percent for such nonpoint sources in eastern Pima County, east of the eastern boundary of the Tohono O'Odham Reservation.
      2.   Forty percent for such nonpoint sources in all other areas of Pima County.
   C.   Open fires permitted according to Chapter 17.14 are exempt from the requirements of this section.
   D.   No person shall cause, suffer, allow, or permit diffusion of visible emissions, including fugitive dust, beyond the property boundary line within which the emissions become airborne, without taking reasonably necessary and feasible precautions to control generation of airborne particulate matter. Sources may be required to cease temporarily the activity or operation which is causing or contributing to the emissions until reasonably necessary and feasible precautions are taken.
      1.   Sources required to obtain an air quality permit under ARS § 49-426, § 49-480 or Section 17.14.040 may request to have the actions constituting reasonably necessary and feasible precautions approved and included as permit conditions. Compliance with such permit conditions shall be considered compliance with this subsection.
      2.   This subsection shall not apply when wind speeds exceed twenty-five (25) miles per hour (using the Beaufort Scale of Wind-Speed Equivalents, or as recorded by the National Weather Service). This exception does not apply if control measures have not been taken or were not commensurate with the size or scope of the emission source.
      3.   This subsection shall not apply to the generation of airborne particulate matter from undisturbed land.
(Ord. 2017-20 § 3 (part), 2017: Ord. 2002-108 § 3, 2002; Ord. 1999-11 § 2, 1999; Ord. 1995-87 § 39, 1995: Ord. 1994-83 § 49, 1994: Ord. 1993-128 § 4 (part), 1993)