Respiratory therapy involves the evaluation, treatment, and care of patients with breathing and other cardiopulmonary disorders such as chronic asthma, emphysema, or cystic fibrosis. Respiratory therapists and technicians practice under the supervision and direction of a physician, but assume the primary responsibility for all respiratory care, therapeutic treatments, and diagnostic procedures. Some of the daily duties of respiratory therapists include performing limited physical examinations, and conducting diagnostic tests on patients to determine their breathing capacity. Respiratory therapists also measure patient's pH levels and lung capacity in order to provide best provide the information need by a physician to diagnose and determine whether the patient has any lung deficiencies. Formal training is necessary for entry into respiratory therapy careers. An associate degree has become the general requirement. Training in respiratory therapy is offered at the postsecondary level by colleges and universities, medical schools, vocational institutes, and respiratory therapy schools. Areas of study in respiratory therapy programs include anatomy and physiology, chemistry, physics, microbiology, pharmacology, and mathematics. Other courses deal with therapeutic and diagnostic procedures and tests, equipment, patient assessment, cardiopulmonary resuscitation, application of clinical practice guidelines, patient care, respiratory health promotion and disease prevention, and rehabilitation. The licensing requirements for respiratory therapy careers vary from state to state, but almost every state requires licensure to practice. Also, most employers require respiratory therapists to maintain CPR certification as well. Hospitals employ the vast majority of respiratory therapists and technicians; however, a growing number of therapists are finding employment outside of hospitals with home healthcare services, or in offices of physicians or other health practitioners.