Massachusetts lawmakers may double the number of cities and towns allowed to ban fossil fuels in new construction. A bill under consideration would add up to 10 communities to an ongoing pilot program that proponents say is already reducing emissions, making homes healthier, and lowering energy bills — all without stifling the development of new housing.

Cities including Salem and Somerville are lining up to participate in an expanded program, and some local leaders in Worcester are eager to take part, too. Boston, the state’s largest city, has previously expressed interest in joining.