Aim: Since the first notified case of occupational asthma in 1983, a total of 90 cases were confirmed as on 31st December 1999. In this study, demographic data, causative agents and impact on the workers were described.
Methods: The data was derived from notifications to the Ministry of Manpower and referrals to the Occupational Lung Disease Clinic jointly run with Department of Respiratory Medicine, Tan Tock Seng Hospital.
Results: Of the 90 cases, 19 (21%) were females and 71 (79%) were males. There were 48 (53%) Chinese, 22 (24%) Malays, 14 (16%) Indians and 6 (7%) of other ethnic origins. The mean age at diagnosis was 35.8 +/- 9.3 yrs. The mean duration of exposure prior to onset of symptoms was 34.9 +/- 57.3 months. The most common causative agent was isocyanates (28 cases, 31%) followed by solder flux (12 cases, 13%) and welding fumes (8 cases, 9%) respectively. Thirteen (14.4%) workers were assessed to have permanent disability under the Workmen's Compensation Act.
Conclusions: Since 1990, occupational asthma has overtaken silicosis and asbestosis as the most common occupational lung disease in Singapore. The most common causative agent is isocyanates. Occupational asthma is a condition associated with disability in the workplace and may still be largely under-reported.