A pulmonologist or chest physician is a doctor who focuses on the respiratory system and treat breathing related conditions. The respiratory system includes nasal cavity, mouth, throat, pharynx, larynx, trachea or windpipe, lungs, bronchi, bronchioles, alveoli (tiny air sacs inside the lungs where the exchange of oxygen and carbon dioxide happen) and pleura (membrane that surrounds the lungs, separating them from the chest wall).  The conditions that pulmonologist commonly treat include:

• Asthma
• bronchiectasis, a condition that involves inflammation and excess mucus
• Acute and chronic bronchitis, which occur when an individual has inflamed lower airways
• chronic obstructive pulmonary disease (COPD), including emphysema, which occurs when the alveoli in the lungs are damaged
• Interstitial lung diseases, which are marked by persistent inflammation and scarring
• Occupational lung disease, which can occur due to inhaling dusts, chemicals, or proteins
• Obstructive sleep apnea, which causes breathing to slow or stop entirely when the individual is sleeping.
• Tuberculosis, an infectious disease that mostly affects the lungs

Pulmonologists may conduct procedures like thoracentesis to drain fluid or air from the pleural space surrounding the lungs and placement of tracheal or bronchial stents to facilitate the opening of airways such as the windpipe or bronchi.