The board is charged with the duty of making effective the declared public policy of the state and municipalities as hereinabove set forth, and for that purpose is hereby authorized and empowered to determine whether the public convenience and necessity require that any municipality shall have the right to acquire lands, and thereon to bring into completion such "standard" industrial districts or parks and to dispose of or rent, let or lease any part or parts or all of such developed parks or districts for industrial purposes.