There is evidence for the need of early investigation and objective categorization of presented symptoms in adult onset asthmatics into occupational asthma (OA), aggravation of underlying asthma, unrelated asthma or other diagnoses. OA should be suspected in all adult onset asthmatics whose asthma begins or worsens while they are working. Investigations should be directed to objective assessment of asthma and then to assessment of the occupational relationship, using a combination of investigations, which may include immunological tests, pulmonary function assessed during work period and away from work, and specific challenge tests.

        Key words: occupational asthma, aggravation of underlying asthma, non-occupational asthma