Questionnaires administered in general populations have shown that about 10–15% of subjects with asthma report that their asthma is worse at work.¹ A proportion of these subjects may show what is called occupational asthma (OA)—that is, asthma caused by an agent inhaled at work. It is important to confirm or exclude a diagnosis of OA for at least two reasons: (1) if a worker with OA continues to be exposed to the causal agent, this can lead to worsening of asthma and diminishes the likelihood of resolution; it has been shown consistently that the duration of exposure with symptoms is the principal determinant of persisting asthma after avoidance of exposure^2,3 and (2) removing a worker from her/his workplace has serious psychosocioeconomic consequences for the worker, often when young, and also for the employer and society.⁴ Advice to leave a job in these circumstances needs to be based on a secure foundation. At a time when expensive high-technology imaging testing is available for all sorts of diseases, it is frustrating that frequently advice to a worker to stay at work or to leave is based only on the clinical history.

In this issue of the journal, …