California Code, Health and Safety Code - HSC § 43000.5

(a) Despite the significant reductions in vehicle emissions which have been achieved in recent years, continued growth in population and vehicle miles traveled throughout California have the potential not only to prevent attainment of the state standards, but in some cases, to result in worsening of air quality.

(b) The attainment and maintenance of the state air quality standards will necessitate the achievement of substantial reductions in new vehicle emissions and substantial improvements in the durability of vehicle emissions systems.

(c) The burden for achieving needed reductions in vehicle emissions should be distributed equitably among various classes of vehicles, including both on- and off-road vehicles, light-duty cars and trucks, and heavy-duty vehicles, to accomplish improvements in both the emissions level and in-use performance and durability of all new motor vehicles.

(d) The state board should take immediate action to implement both short- and long-range programs of across-the-board reductions in vehicle emissions and smoke, including smoke from heavy-duty diesel vehicles, which can be relied upon by the districts in the preparation of their attainment plans or plan revisions pursuant to Sections 40911, 40902, and 40925.

(e) In order to attain the state and federal standards as expeditiously and equitably as possible, it is necessary for the authority of the state board to be clarified and expanded with respect to the control of motor vehicles and motor vehicle fuels.