Assessment of Asthma in the Workplace

Occupational asthma has become the most common form of occupational lung disease in many industrialized countries. In France and the United Kingdom, the number of claims for occupational asthma each year exceeds that of pneumoconiosis.1,2 Finland has seen a steady increase in the number of cases of occupational asthma reported to the Occupational Diseases Registry.3 In Canada, the frequency of occupational asthma has also increased considerably in Quebec.4 A surveillance program for occupational lung disease in the United Kingdom showed that asthma was the most frequently reported condition in 1989.5 Recent studies indicate that environmental exposures account for up to 40% of the cases of asthma6 and that 15% of all cases of asthma are attributed to workplace exposure.7 Although more conservative estimates suggest that occupational exposures account for 2% of all asthmatic patients.8 it remains clear that the prevalence of asthma at individual worksites is largely dependent on the risks inherent in the specific occupational exposure. The prevalence of asthma can be as high as 50% for workers exposed to proteolytic enzymes,9 down to approximately 5% among some groups of workers exposed to either isocyanates10 or wood dust from western red cedar.11

Identified cases of occupational asthma very likely represent a small proportion of all cases of occupational asthma. The diagnosis of occupational asthma is often difficult because of (1) its multiple potential causes in many industrial environments, (2) the variability of symptoms and patterns of late-phase asthmatic reactions, (3) the requirement of specific diagnostic procedures, and (4) the unpredictability of onset and persistence of symptoms. A consensus conference on the assessment of asthma in the workplace is timely.

This document provides a state-of-the-art approach to the assessment and management of asthma in the workplace. It is intended for pulmonologists, allergists, and specialists in occupational and environmental medicine.