Asthma control in the workplace.

Workplace exposures may result, in susceptible workers, in the development of occupational asthma from sensitising or toxic/irritant exposure, or in the worsening of a pre-existing asthmatic condition, so-called ‘‘work-exacerbated asthma’’ [1–3]. Occupational asthma is a relatively common condition, although it is often unrecognised [1, 4]. Exposure to the sensitising agents can lead to permanent airway changes, so that even when stopped, the majority of workers will still experience persistent asthma symptoms and show residual airway hyperresponsiveness [2–5]. Early cessation from exposure to the offending agent, however, results in a better prognosis, while persistent exposure can lead to more severe asthma and more frequent acute asthma events [5, 6].