Acute respiratory health effects among cement factory workers in Tanzania: an evaluation of a simple health surveillance tool
Objectives: The effects of cement dust exposure on acute respiratory health were assessed among 51 high exposed and 33 low exposed male cement workers. The ability of the questionnaire to diagnose acute decrease in ventilatory function was also assessed. Methods: Acute respiratory symptoms were recorded by interview using a structured optimal symptom score questionnaire. Peak expiratory flow (PEF) was measured preshift and postshift for each worker with a Mini-Wright PEF meter. Personal respirable dust (n=30) and total dust (n=15) were measured with 37-mm Cyclone and 37-mm closed-faced Millipore cassette. Twenty-nine workers had concurrent respirable dust, PEF and questionnaire on the same day. Results: The geometric means of personal respirable dust and total dust among high exposed were 4.0 and 13.2 mg/m3, respectively, and 0.7 and 1.0 mg/m3 among low exposed. High exposed workers had more acute cough, shortness of breath and stuffy nose than the low exposed. Mean percentage cross-shift decrease in PEF was significantly more pronounced among high exposed workers than low exposed (95% CI 1.1, 6.1%). For workers with concurrent respirable dust, PEF and questionnaire assessment, an exposure–response relationship was found between log-transformed respirable dust and percentage cross-shift decrease in PEF (4.5% per unit of log-respirable dust in mg/m3 ; 95% CI 3.3, 5.6%). Respirable dust exposure =2.0 mg/m3 versus <2.0 mg/m3 was associated with increased prevalence ratio for cough (7.9) and shortness of breath (4.2). Shortness of breath was associated with the highest sensitivity (0.87) and specificity (0.83) for diagnosing a percentage cross-shift decrease in PEF of =10%. Conclusion: The observed acute respiratory health effects among the workers are most likely due to exposure to high concentrations of irritant cement dust. The results also highlight the usefulness of the questionnaire for health surveillance of the acute respiratory health effect.