Reported incidence of occupational asthma in the United Kingdom, 1989-90

To estimate the incidence of occupational asthma seen by respiratory and occupational physicians in the UK in 1989 and 1990.

New cases of occupational asthma were taken from a national reporting scheme, the Surveillance of Work-related and Occupational Respiratory Disease Project (SWORD). Estimates of the working population from the Labour Force Survey were used to calculate reported incidence by age group, sex, occupation, and region.

The SWORD project is a scheme for the reporting of new cases of work-related respiratory disease by thoracic and occupational physicians from throughout the UK which began in 1989.

In 1989 and 1990, of 4229 cases reported, 1085 (26%) were in patients with occupational asthma.

Only half the reported cases were attributed to agents prescribed under the Industrial Injuries Scheme. There was considerable diversity in risk by occupation, with highest annual rates in welders, solderers, and electronic assemblers (175/million), laboratory workers (188/million), metal treaters (267/million), bakers (334/million), plastics workers (337/million), chemical processors (364/million), and spray painters (658/million). Crude rates in men were higher than in women, but rates within occupations were similar in both sexes. Rates of disease rose with age; adjustment for occupation increased the gradient. Regional differences were only partly explained by diversity of industry and were probably mainly due to variation in levels of ascertainment and reporting.

Asthma is the most commonly reported occupational lung disease in the UK. The incidence in the general population is unknown, but it was estimated that the incidence of new cases seen by respiratory and occupational physicians was about three times that reported. High relative risks were found in a number of occupations in which effective control of the work environment is urgently required.