A variety of occupational asthma is induced by important exposure to irritants. A case is reported, where le patient developed asthma symptoms like, following huge exposure to sulfur dioxide. All Books criteria were met, except for the metachlorine challenge which was not performed. Nevertheless the bronchial reactivity in the work place, shown by a portable pick flow eased le diagnosis. General practitioners and occupational physicians should be aware of this new medical entity for a better management.