Causes of lung cancer among nonsmokers:

Secondhand smoke exposure.
Radon gas exposure in dwellings.
Environmental contaminants include asbestos, diesel exhaust, and arsenic.
Genetic influences and family history.
Occupational exposure to specific chemicals or carcinogens.

Pneumothorax

It is a condition in which air enters the area between the lung and the chest wall, resulting in lung collapse.

Symptoms:
Sudden and intense chest pain.
Shortness of breath.
Rapid breathing.
Reduced breath sounds on the afflicted side.
Cyanosis (bluish skin colour).
Chest tightness.

COPD, or chronic obstructive pulmonary disease

It is a lung condition that makes breathing hard. It slowly worsens over time and is usually caused by smoking.
Airflow is blocked, making it hard to inhale and exhale.
Symptoms include breathlessness, wheezing, and a persistent cough.