While the state Board of Environmental Protection continues to take testimony on ways to meet air-emission standards, it should require that any system it adopts be cost effective and simple to implement.

The California standards presented to the BEP last week meet both these requirements. The standards for new cars and light trucks would instruct auto manufacturers to produce cleaner-burning engines. Ford has said it could produce engines that meet the standards for only an additional $100, which it said it would not pass on to customers. Other manufacturers said a fast-heating catalytic converter could do the job well and cheaply.

Massachusetts and New York were the first states in the Northeast to adopt the tougher standards. If Maine and other regional states do so as well, it could drop air pollution here by as much as 30 percent without adding significantly to the cost of owning or operating an automobile. Used cars wouldn’t be affected by the new rules, and there are further exceptions that allow for fleet averages to meet the tougher requirements.

Cleaner-burning engines will help the state meet the Clean Air Act standards, which it must do if it is to escape federal punishment, such as loss of highway dollars or traffic-control measures. For the California rules, the first emission standards for hydrocarbons, carbon monoxide and nitrogen oxides would come into effect in 1994. The new engine standards would apply to 1996 vehicles, with California, which had already planned to institute the measures, picking up the cost of monitoring compliance.

Because air doesn’t respect state boundaries, regional cooperation on lowering air-pollution levels is essential. The California standards offer a practical, affordable way to help clean Maine’s skies.