Risk Factors and Causes

  1. Tobacco exposure (current or past smoking; and secondhandsmoke)
  2. Airpollution
  3. Environmental exposure to arsenic, radon, soot, beryllium, chromium andnickel
  4. Geneticpredisposition
  5. Olderage
  6. Exposure toradiation
  7. Comorbidities such as HIV and chronic obstructive pulmonarydisease