Occupational obstructive disorders: nonspecific airways obstruction and occupational asthma

Airways obstruction as a result of occupational exposure may be divided into two categories on the basis of whether or not occupational asthma is present. The first category, nonspecific airways obstruction, takes place in the absence of occupational asthma, and demonstrates only modest changes in airways responsiveness. The second category, occupational asthma, usually has a causal relationship to exposure, and demonstrates marked changes in airways responsiveness. These distinctions are of use in diagnosis, treatment, and disability assessment.