Disorders of the respiratory system occur at all ages. In many countries the high level of environmental pollution in the past, together with the popularity of tobacco, has meant that there have always been many people suffering form respiratory conditions, particularly bronchitis.

Common diseases of the respiratory system may be related to infections, such as bronchitis and pneumonia, or to allergies. Details are provided below about:

1) Asthma.
2) Emphysema and COPD.
3) The common cold and flu.
4) Bronchitis.