In the United States, the paramedic is a professional whose primary focus is to provide advanced emergency medical care for critical and emergency patients who access Emergency Medical Services (EMS). This individual possesses the complex knowledge and skills necessary to provide patient care and transportation. Paramedics function as part of a comprehensive EMS response, under medical oversight. Paramedics perform interventions with the basic and advanced equipment typically found on an ambulance. The paramedic is a link from the scene into the health care system. One of the eligibility requirements for state certification or licensure requires successful completion of a nationally accredited Paramedic program at the certificate or associate degree level. Each state varies in requirements to practice as a paramedic, and not all states require licensure. History Prior to 1970, ambulances were staffed with advanced first-aid level responders who were frequently referred to as "ambulance attendants." There was little regulation or standardized training for those staffing these early emergency response vehicles or the required equipment carried inside. Around 1966 in a published report entitled "Accidental Death and Disability: The Neglected Disease of Modern Society", (known in EMS trade as the White Paper) medical researchers began to reveal, to their astonishment, that soldiers who were seriously wounded on the battlefields of Vietnam had a better survival rate than those individuals who were seriously injured in motor vehicle accidents on California freeways. Early research attributed these differences in outcome to a number of factors, including comprehensive trauma care, rapid transport to designated trauma facilities, and a new type of medical corpsman; one who was trained to perform certain critical advanced medical procedures such as fluid replacement and airway management, which allowed the victim to survive the journey to definitive care. During the 1960s a Los Angeles cardiologist named Walter S. Graf became concerned about the lack of actual medical care being given to coronary patients during emergency transportation to a hospital. In 1969, while serving as president of the Los Angeles Chapter of the American Heart Association, he created a "mobile critical care unit", consisting of a Chevy van, a registered nurse, and a portable defibrillator. The same year his patient Kenneth Hahn, a member of the Los Angeles County Board of Supervisors, persuaded the Supervisors to approve a pilot program to train county firefighters as "Mobile Intensive Care Paramedics". A change in state law was necessary to allow personnel other than