Most workers with occupational asthma who remain exposed to the causative agent have accelerated loss of FEV₁1 and recover less when eventually removed from exposure than those removed within the first year of occupational asthma symptoms.2 The reasons for this are not obvious, as most childhood onset asthmatics remain exposed to the causative allergens and infrequently develop severe airflow obstruction later in life. It is possible that the timing of exposure related to the maturity of the immune system is critical, and the development of a degree of tolerance is more common in childhood than later in life. Whatever the reasons, the recommendation for removal from exposure within a year of first occupational asthma symptoms is based on good evidence.2

There is an established societal view that those disabled by their work through no fault of theirs are entitled to some form of compensation. How this is achieved varies widely between countries. Most countries rely on an insurance-based system, sometimes with support from the government.3 In the UK there is a dual system with a no-fault compensation system without employer contribution funded by the central government and a common law system which requires the establishment of negligence on the part of the employer. Neither work well in the context of occupational asthma. Central to compensation is the assessment of …