This board shall be composed of no fewer than fifteen and no more than twenty five members appointed by the county executive for two year terms. One third of the members shall be active members of volunteer fire companies operating rescue squads or ambulance services and the remaining membership shall be elected officials or their representatives, representatives of ambulance services, hospitals, fire department emergency and rescue squads, public health officers and other agencies, organizations or citizens involved in the planning or provision of emergency medical services. The county executive shall designate one of the members to serve as chairman. It will be the duty of such board to cooperate with the state health department's bureau of emergency medical services in effectuating the purposes for which the bureau was established in relation to programs for emergency medical services; to act as an advisory board to the county executive, the county legislature, the commissioner of emergency services and the deputy commissioner of emergency medical services in connection with county establishment and maintenance of a county emergency medical services and mutual aid program for medical and other emergencies in which the services of emergency medical personnel would be used. Members of such board shall be county officers and shall serve without compensation.