Critical aspects of the history of occupational asthma

: The medical history is the gateway to the diagnosis of occupational asthma. The medical history should indicate whether a patient's asthma began during a work period and whether the asthma worsens during work periods or improves on days when the patient is off work or on holidays. A suspicion of sensitizer-induced occupational asthma will increase if the patient was exposed to a recognized respiratory sensitizer in the workplace at the time of the onset of symptoms or if the patient had associated symptoms of allergic rhinitis and conjunctivitis. A history of accidental high respiratory irritant exposure shortly before the initial onset of symptoms would raise the possibility of irritant-induced occupational asthma. Although such features of the history are sensitive indicators of occupational asthma, they are not specific and should therefore be followed by further investigations to confirm the diagnosis of asthma and its relation to the workplace exposure. The earlier the diagnosis is suspected and investigated, the better the outcome is likely to be for the patient.