BRONCHIAL-ASTHMA IN 2 CHEMICAL FERTILIZER PRODUCING FACTORIES IN EASTERN SAUDI-ARABIA

SETTING: Two urea fertilizer producing factories in Saudi Arabia. OBJE CTIVE: To determine the prevalence of respiratory symptoms and disease s in employees exposed to ammonia gas. DESIGN: A cross-sectional study involving 161 exposed subjects and 355 controls. All completed a resp iratory symptoms questionnaire, with additional questions on present a nd past occupations. Ammonia concentrations were measured in the diffe rent sections of the factories. RESULTS: The ammonia levels in factory B were well below the threshold limit value (TLV) (range 0.02-7.0 mg/ m(3) of air). In factory A the range was 2.0-130.4 mg/m(3). The contro l and exposed groups were comparable with respect to their smoking hab its. The exposed subjects in factory A had significantly higher relati ve risks (RR) for all respiratory symptoms; the same was true for haem optysis (RR: 4.1, 95% confidence interval: 1.63-10.28). Bronchial asth ma, chronic bronchitis, and a combined diagnosis were significantly hi gher among those exposed to high cumulative ammonia levels. However, i n the logistic regression analysis ammonia concentration was significa ntly related to cough, phlegm, shortness of breath with wheezing and b ronchial asthma. CONCLUSION: Exposure to ammonia gas in the workplace is significantly associated with increase in respiratory symptoms and bronchial asthma. Re-engineering measures to lower the levels of ammon ia in factory A are strongly recommended. The affected employees shoul d be removed from further exposure and followed up.