Mediastinum: The area that separates the lungs from each other.
Screening: Looking for signs of disease such as cancer in people who are symptom-free.
Passive smoking: A non-smoker inhaling the cigar, cigarette, or pipe smoke of others (called second-hand smoke) in the same area. This increases the non-smoker's risk of cancer and respiratory disorders.
Radioactivity: A process by which a substance spontaneously emits radiations.
Radon: A naturally occurring radioactive element.
Emphysema: Pulmonary emphysema is a disorder affecting the alveoli (tiny air sacs) of the lungs. The transfer of oxygen and carbon dioxide in the lungs takes place in the walls of the alveoli. In emphysema, the alveoli become abnormally inflated, damaging their walls and making it harder to breathe. People who smoke or have chronic bronchitis have an increased risk of emphysema.