Pulmonologists are physicians who, after receiving a medical degree (MD or DO), complete residency training in internal medicine, followed by at least two additional years of subspeciality fellowship training in pulmonology.
After satisfactorily completing a fellowship in pulmonary medicine, the physician is permitted to take the board certification examination in pulmonary medicine. After passing this exam, the physician is then board certified as a pulmonologist.
Most pulmonologists complete three years of combined subspecialty fellowship training in pulmonary medicine and critical care medicine.
Source: Wikipedia.org
