SDAPCD RULE 50 PROHIBITIONS          
LAST REVISED 03/18/86

          
          REGULATION IV.      PROHIBITIONS    (Effective 1/1/69)


               RULE 50.  VISIBLE EMISSIONS   (Rev. Effective 3/18/86)

               (a)  APPLICABILITY

               Except as otherwise provided in Section (b), this rule
          applies to the discharge of any air contaminant other than
          uncombined water vapor.

               (b)  EXEMPTIONS

               The provisions of this rule shall not apply to:

                    (1)  Smoke from the use of an orchard or citrus grove
               heater which does not produce unconsumed solid carbonaceous
               matter at a rate in excess of one gram per minute;

                    (2)  Emissions from the use of equipment in
               agricultural operations;

                    (3)  Smoke from open fires set pursuant to a permit and
               its conditions;

                    (4)  Abrasive blasting operations subject to the
               provisions of Rule 71 of Regulation IV of these Rules and
               Regulations; and

                    (5)  The use of visible emissions generating equipment
               in training sessions conducted by governmental agencies for
               the purpose of certifying persons to evaluate visible
               emissions from compliance with applicable provisions of the
               State of California Health and Safety Code and District
               Rules and Regulations.

               (c)  DEFINITIONS

                    (1)  "Observer" means a certified human observer or a
               certified, calibrated opacity monitoring system.

                    (2)  "Single Source" means any or all units of
               equipment at a given location, including associated outlets
               to the atmosphere, which may be operated simultaneously.

                    (3)  "Asphalt Plant Drop Zone" means the area
               immediately below a device in an asphalt manufacturing
               facility that loads or drops asphalt onto the cargo beds of
               trucks and trailers.

               (d)  STANDARDS

                    (1)  Except as otherwise provided in Section (b) above
               and Subsection (d)(2) below, a person shall not discharge
               into the atmosphere from any single source of emissions
               whatsoever any air contaminant for a period or periods
               aggregating more than three minutes in any period of 60
               consecutive minutes which is darker in shade than that
               designated as Number 1 on the Ringelmann Chart, as published
               by the United States Bureau of Mines, or of such opacity as
               to obscure an observer's view to a degree greater than does
               smoke of a shade designated as Number 1 on the Ringelmann
               Chart.

                    (2)  A person shall not discharge into the atmosphere
               from any diesel pile driving hammer or from any asphalt
               plant drop zone any contaminant for a period or periods
               aggregating more that three minutes in any period of 60
               consecutive minutes which is as dark or darker in shade than
               that designated as Number 2 on the Ringelmann Chart, as
               published by the United States Bureau of Mines, or of such
               opacity as to obscure an observer's view to a degree greater
               than does smoke of a shade designated as Number 2 on the
               Ringelmann Chart.

               In accordance with Section 41701.5 of the State Health and
          Safety Code, diesel pile driving hammers shall comply with
          Subsection (d)(1) above after December 31, 1986.