Characteristics and Determinants of the Presence of Respiratory Symptoms among Sewage Workers in Malaysia

Abstract

Background. The purpose of this study was to determine the relationships of PM 2.5 and H2S exposure with the presence of work-related respiratory symptoms among sewage workers. Methods. A cross-sectional study was conducted in eleven sewage plants located in the central region of Peninsular Malaysia. One hundred ninety-one sewage workers were assessed using the British Medical Research Council (BMRC) questionnaire. Area air sampling was performed in three different sewage plants to measure the following parameters: physical air quality and concentration of PM 2.5 and H2S. Result. Chronic cough (34.0%) was reported as the most common symptom, followed by chronic phlegm (26.2%), shortness of breath (7.9%), and chest tightness (3.7%). There were five significant determinants of the presence of respiratory symptoms among the sewage workers: shift work (AOR 23.50, 95% CI: 1.90-616.52), working at a sludge treatment facility (STF) (AOR 25.46, 95% CI: 2.06-314.29), a longer duration of working years (AOR 1,21, 95% CI: 1.01-1.44), individual cumulative exposure to PM 2.5 (AOR 9.01, 95% CI: 1.98-83.33), and individual cumulative exposure to H2S (AOR 1.04, 95% CI: 1.01-1.07). The majority of STF and non-STF workers had higher exposure to PM 2.5 and H2S concentrations in the air than office workers. Conclusion. Sewage workers working at non-STFs or STFs reported a significantly higher prevalence of work-related respiratory symptoms and exposure to PM 2.5 and H2S compared with office workers. Exposure-response relationships were also found in sewage workers' cumulative exposure to PM 2.5 and H2S and the presence of respiratory symptoms.