Section 142D. The department, with the approval of the governor, may establish air pollution control districts compatible with such air quality control regions as may be designated by the secretary of the federal department of health, education and welfare under the provisions of the Air Quality Act of 1967, or any additions or amendments thereto. The department, with the approval of the governor, may add to or remove from air pollution control districts such cities and towns, and may establish or abolish such other air pollution control districts, as it may deem advisable and necessary to effect air pollution control in the commonwealth. The department may adopt, and from time to time amend, after public hearings, ambient air quality standards applicable to said districts and to other portions of the commonwealth, and shall adopt a plan for the implementation, maintenance and attainment of such standards. The powers, duties and rights of the department in the exercise of air pollution control in districts established under this section and the manner in which funds shall be made available to it shall be as provided in section one hundred and forty-two B.

From time to time the department shall review the ambient air quality standards and plan for implementation, maintenance and attainment of such standards adopted pursuant to this section and, after public hearings, shall amend such standards and implementation plan so as to minimize the economic cost of such standards and plan for implementation, provided, however, that such standards shall not be less than the minimum federal standards. The initial such amendments to such standards and implementation plan shall postpone the achievement dates for the primary and secondary ambient air quality standards to the latest dates permitted pursuant to federal law. Any compliance schedule, emission limitation, for new or existing facilities, order, rule, plan or regulation adopted pursuant to such standards or implementation plan shall be amended to conform to such amended standards and implementation plan upon petition of the owner or operator of a facility whose construction, maintenance or operation is affected by such compliance schedule, emission limitation, for new or existing facilities, order, rule, plan or regulation. The department shall, after opportunity for public hearing, issue a final order with respect to the subject matter of such petition within sixty days of the filing of the petition.

In any standard, implementation plan, compliance schedule, emission limitation, for new or existing facilities, order, rule, plan or regulation where the sulphur or ash content, or other chemical or physical characteristic of fuels or emissions therefrom is subject to consideration by the department, the department shall allow stack height, fuel switching and variations in plant operation to be used instead of controls on such sulphur or ash content or chemical or physical characteristic of such fuels or emissions therefrom if the owner or operator of the facility shall demonstrate to the satisfaction of the department that such controls are not necessary to achieve ambient air quality standards; provided, however, the department may impose conditions necessary to minimize public nuisance and adverse effects to the public health. If a variance or other permission granted by the department with respect to the sulphur or ash content, or other chemical or physical characteristic of fuels or emissions therefrom would otherwise prevent the achievement of primary or secondary federal ambient air quality standards within a time period required by the express language of a federal statute or regulation such variance or other permission shall be limited to the maximum time period allowed by federal law.