(1) Every activated authority operating an air pollution control program shall have requirements for the control of emissions which are no less stringent than those adopted by the department of ecology for the geographic area in which such air pollution control program is located. Less stringent requirements than compelled by this section may be included in a local or regional air pollution control program only after approval by the department of ecology following demonstration to the satisfaction of the department of ecology that the proposed requirements are consistent with the purposes of this chapter: PROVIDED, That such approval shall be preceded by public hearing, of which notice has been given in accordance with chapter
42.30 RCW. The department of ecology, upon receiving evidence that conditions have changed or that additional information is relevant to a decision with respect to the requirements for emission control, may, after public hearing on due notice, withdraw any approval previously given to a less stringent local or regional requirement.
[(2)] Nothing in this chapter shall be construed to prevent a local or regional air pollution control authority from adopting and enforcing more stringent emission control requirements than those adopted by the department of ecology and applicable within the jurisdiction of the local or regional air pollution control authority, except that the emission performance standards for new woodstoves and the opacity levels for residential solid fuel burning devices shall be statewide.