Introduction
This topic covers the allergic and dust-related airway diseases caused by work. The core is occupational bronchial asthma, the most common occupational respiratory allergic disease, followed by byssinosis, a textile-dust disease with a characteristic pattern of chest tightness. A good exam answer covers definition, classification, causes, pathogenesis, clinical picture, diagnosis with criteria for occupational origin, differential diagnosis, treatment, and medical expertise.
Occupational bronchial asthma: definition and classification
Occupational asthma is variable airflow limitation and airway hyperresponsiveness caused by agents present at the workplace. It must be distinguished from pre-existing asthma that is only made worse by work. Three forms are recognised: sensitiser-induced asthma (immunological, after a latency period), irritant-induced asthma (reactive airways dysfunction syndrome after a single high-level exposure), and work-exacerbated asthma in a person who already has asthma.
Severity is judged on the asthma as it is now. Together with the work history, it guides treatment and decisions about whether the worker can stay in the same job.