An assessment of dust exposure levels and factors associated with the occurrence of respiratory symptoms among workers in the road construction industry in Lusaka, Zambia

Abstract

Research into dust exposure in the road construction industry and the prevalence of respiratory symptoms in Zambia has not been extensively conducted despite the respiratory symptoms forming the primary burden of occupational illnesses in Zambia. The absence of literature in this industry on occupational respiratory health symptoms and database for these workers formed the rationale for this present study. This study assessed respirable dust exposure levels and factors associated with the occurrence of occupation respiratory health symptoms in Lusaka district (n=145). A cross sectional survey among road construction workers, conducted at three road construction sites; (Lusaka-Chisamba), (Lusaka- Kafue) and (Matero - Lilanda) roads. Personal dust samplers were used to assess the dust exposure levels and an adapted American thoracic health questionnaire was used to capture respiratory symptoms and factors associated with the occurrence of respiratory health symptoms. Spirometry test was also used to determine the lung function capacity of the road construction workers. Fisher’s exact test was used to test for bivariate associations and logistic regression was used for crude and adjusted multivariate analysis between social demographic factors, job category, cumulative respirable dust, use of PPE, smoking and years exposed. The prevalence of respiratory symptoms was nose irritation (59.3%), wheezing (45%) phlegm 29% and shortness of breath (39.3%).The mean respirable dust exposure level was 1.768mg-yr/m3. Exposure to a cumulative respirable dust concentration of ≥1.768mg-yrs/m3 was significantly associated with shortness of breath (OR 1.317; 95% CI; 0.125-0.802), (p-value (0.015). On factors associated with the occurrence of respiratory symptoms, education levels (tertiary education) was significantly associated with nose irritation (OR 0.257,95%CI; 0.076-0.862), (p-value 0.028) and job category (land clearing works) (OR 2.382; 95% CI;0.159-0.919), (P-value 0.032).The non-use of personal protective equipment by workers was significantly associated with respiratory symptom phlegm (OR 1.256, 95% CI;3.526-3.384), (p-value (0.007) and wheezing (OR 3.775,95% CI; 1.416-1.958), (p-value 0.008). The spirometry test results showed that 96% of the road construction workers had normal lung function, while only 4% of the workers had mildly to moderate lung impairment with the force expiratory volume ratio (FEV1) between 60% - 79%. It is therefore, recommended that dust control measures be put in place at road construction sites in order to prevent dust exposure and the occurrence of respiratory symptoms and diseases. Key words: Dust Exposure, Factors Associated, Respiratory Symptoms, Prevalence and Use of PPE