A pulmonologist is a doctor who specializes in diagnosing and treating diseases of the lungs and respiratory system. This includes everything from the airways and windpipe to the tiny air sacs deep in your lungs and the blood vessels that carry oxygen into your bloodstream. If you have a breathing problem that your primary care doctor can’t fully manage, a pulmonologist is typically the next step.
What a Pulmonologist Does
Pulmonologists handle both chronic conditions you live with for years and acute problems that develop suddenly. On the chronic side, they manage diseases like asthma, COPD (chronic obstructive pulmonary disease), interstitial lung disease (scarring of the lung tissue), and pulmonary hypertension (high blood pressure in the arteries of the lungs). On the acute side, they treat severe pneumonia, respiratory failure, blood clots in the lungs, and pleural effusions (fluid buildup around the lungs).
Unlike a thoracic surgeon, who operates on the lungs and chest, a pulmonologist focuses on medical management. They figure out what’s wrong, prescribe treatment plans, monitor your lung function over time, and adjust therapy as your condition changes. If surgery becomes necessary, a pulmonologist will typically coordinate with a thoracic surgeon rather than perform the procedure themselves.
Tests and Procedures They Perform
Much of a pulmonologist’s work involves measuring how well your lungs function and figuring out why they’re not working properly. The most common tool is spirometry, a simple breathing test that measures how much air you can blow out and how fast. You breathe forcefully into a tube, and the results reveal whether your airways are narrowed or obstructed. Lung volume tests measure the total amount of air your lungs can hold, while diffusion capacity tests check how efficiently oxygen moves from your lungs into your blood.
For a quick snapshot, pulse oximetry clips onto your finger and estimates oxygen levels in your blood. When more precision is needed, an arterial blood gas test draws blood directly from an artery to measure exact oxygen and carbon dioxide levels. Exhaled nitric oxide tests can detect airway inflammation, which is especially useful for diagnosing and monitoring asthma.
Beyond breathing tests, pulmonologists use imaging like chest X-rays, CT scans, and MRIs to visualize the lungs in detail. CT scans are particularly valuable because they produce 3D models showing the size, shape, and position of lung structures. When imaging alone isn’t enough, a pulmonologist may perform a bronchoscopy: threading a thin, flexible tube with a camera through your nose or mouth, down into your airways. This lets them look directly at the inside of your lungs, take tissue or mucus samples, identify infections or tumors, clear blockages, or place small stents to keep narrowed airways open.
Subspecialties Within Pulmonology
Not all pulmonologists do the same work. Many pursue combined training in pulmonary and critical care medicine, which qualifies them to manage patients in intensive care units who need mechanical ventilation or are in respiratory failure. This combined path is actually the most common training route in the United States.
Interventional pulmonology is a growing subspecialty focused on advanced procedures. These specialists use specialized tools to place airway stents, remove tumors blocking the airways, and perform minimally invasive biopsies. Some pulmonologists also specialize in sleep medicine, diagnosing and treating conditions like sleep apnea that affect breathing during sleep. Others focus on lung transplant care, managing the complex medical needs of patients before and after receiving a new lung.
Training and Certification
Becoming a pulmonologist requires a long training path. After four years of medical school, a doctor completes a three-year residency in internal medicine. That first year of residency is the internship, an intensive period of hands-on clinical work. Only after finishing all three years can a physician apply for a pulmonary fellowship.
A fellowship in pulmonary disease alone takes two years, with at least 12 of those months in direct clinical training. The more common combined pulmonary and critical care fellowship takes three years, with a minimum of 18 months of full-time clinical work. During fellowship, trainees must develop competency in a wide range of procedures: bronchoscopy, managing patients on ventilators, inserting chest tubes, performing thoracentesis (draining fluid from around the lungs), placing central venous catheters, and conducting exercise testing.
After completing fellowship, physicians must pass the Pulmonary Disease Certification Examination administered by the American Board of Internal Medicine. They also need a valid, unrestricted medical license. All told, from the start of medical school to board certification, the process takes at least nine years, and ten or more for those pursuing dual certification in critical care.
When You Might See a Pulmonologist
Most people see a pulmonologist through a referral from their primary care doctor. A persistent cough lasting more than a few weeks, shortness of breath that can’t be explained by your fitness level, wheezing, chest tightness, or coughing up blood are all reasons your doctor might send you to one. Chronic conditions like asthma that aren’t responding well to standard treatment, or a new diagnosis of COPD, often prompt a referral for specialized management.
You might also see a pulmonologist if you have an abnormal chest X-ray or CT scan, recurring pneumonia, unexplained weight loss paired with breathing symptoms, or if you need evaluation before lung surgery. People with autoimmune diseases that affect the lungs, occupational exposures to dust or chemicals, or a family history of lung disease may also benefit from a pulmonologist’s expertise. The goal is always the same: get a clear diagnosis, understand what’s driving the problem, and build a treatment plan that keeps your lungs working as well as possible.