There are two lungs in the chest– one on the right side and the other on the left side. These lungs are surrounded by a thin cover (pleura), which ensures smooth movement of lungs during breathing. Impure blood is pumped into the lungs from the right side of heart. In lungs, blood gets oxygen from air and releases carbon dioxide into the air. Purified blood reaches the left side of heart from the lungs so that it can be supplied to the body.
There are many diseases that can affect lungs. Common are infections (pneumonitis, lung abscess, bronchiectesis and T.B.), cancers, chronic obstructive airway disease (related to smoking, air pollution etc.) and interstitial fibrosis (shrinkage of lungs due to many known and unknown causes). All these result in symptoms like cough, expectoration, breathing difficulty and fever. For some of these conditions, if improvement is not adequate with medical treatment, the patient may have to go in for surgery like lobectomy (removal of part of lung) or pneumonectomy (removal of total lung).
Similarly some conditions can affect pleura also –– like collection of air, fluid or blood. This may be because of infections like T.B. or even cancer. Your doctor will decide what is best for you in those situations.