Introduction
This topic covers occupational chronic bronchitis, a chronic inflammatory disease of the airways caused or aggravated by long-term inhalation of harmful agents at work. An exam answer should give the definition and classification, the causes and mechanism, the stages of the clinical course, the diagnostic approach including the criteria for an occupational origin, the differential diagnosis, treatment, and the principles of medical expertise.
Definition and classification
Chronic bronchitis is defined clinically by a productive cough on most days for at least three months in each of two consecutive years, without another cause such as bronchiectasis or tuberculosis. When the cause is an occupational exposure, the disease is called occupational chronic bronchitis. It is part of the group of chronic obstructive pulmonary diseases (COPD), and the occupational forms are usually classified as follows:
Etiology and risk factors
The disease results from the combined effect of several factors. In the workplace the main causes are:
- Dusts: mineral dusts (silica, coal, cement, grain and wood dust), organic dusts and cotton dust.
- Irritant gases and fumes: sulfur dioxide, nitrogen oxides, ozone, chlorine, ammonia, hydrogen fluoride, cadmium and welding fumes, and some organic solvent vapours.
- Microclimate: cold, damp or dry air, sharp temperature changes and high dust load in poorly ventilated premises.
Non-occupational factors are essential in the differential picture and often act together with the work exposure:
- Tobacco smoking, the most important single cause, which multiplies the effect of occupational dusts.
- Alpha-1-antitrypsin deficiency, which predisposes to emphysema, especially in smokers.
- IgA deficiency and recurrent respiratory infections, including repeated childhood infections.
- General urban air pollution.