Background: Little is known about the risk of occupational asthma or its causative agents in South Africa. The objective of this study was to determine the proportion of adult asthmatics whose asthma may be occupational, and the main agents or occupations involved.
Design and setting: A descriptive surveillance study of adult patients presenting with acute asthma to the casualty units of two large public hospitals in Cape Town.
Methods: A brief questionnaire was completed by the casualty staff for a sample of 140 adult asthmatic patients. Respondents were classified as having possible occupational asthma on the basis of adult-onset asthma, exposure at time of onset to a known or suspected cause of occupational asthma, and symptoms that improved away from work.
Results: Eighteen patients (12.9%, 95% confidence interval (CI) 7.8-19.6%) met the criteria for occupational asthma. The main occupational categories in this group were spray painters (4 patients) and domestic workers (4 patients), with cleaning agents, dyes and paints being the most commonly reported exposures. A total of 36 patients (25.7%, 95% CI 18.7-33.7%) reported work aggravation of their asthma.
Conclusions: A clinically significant proportion of adult-onset asthmatics, men and women, may have occupational causation, while an even larger proportion may have occupational aggravation. Since early intervention favourably influences prognosis in occupational asthma, all practitioners dealing with adult asthmatics should explore occupational factors.