Dust Exposure, Fractional Exhaled Nitric Oxide and Respiratory Symptoms among Volcanic Rock Miners in Kilimanjaro, Tanzania

Abstract

Volcanic rock for use as building material is mined extensively in the North Eastern Region of Tanzania. Dust emitted from the rock may contain harmful elements such as crystalline silica, arsenic (As), cobalt (Co), boron (B) and mercury (Hg) which might contribute to severity and onset of health symptoms. Objective: This study assessed respiratory symptoms and fractional exhaled nitric oxide as a marker for respiratory inflammation in relation to dust exposure among workers in different job sections in volcanic block mining. Materials and Methods: A cross-sectional study assessed a total of 135 workers in which 70 were exposed and 65 none exposed. The mining activities are mainly manual, and include cutting of blocks underground, transporting blocks to the shaping area, shaping blocks, loading blocks and aggregates (Murom) to vehicles and clearing or expanding the site. Respiratory health questionnaires were administered through face–to-face interviews. A total of 28 samples of “total” dust were collected around the breathing zone of the workers using SKC Sidekick pump (model 224–50) with a flow rate of 2.0 l/min. FENO assessed respiratory system inflammation using a portable electrochemistry-based sensor (NIOX MINO). Findings: The overall arithmetic mean concentration of personal total dust exposure among the workers was 4.37 mg/m3 (range 0.15-20.84). The prevalence of acute cough and red eyes were significantly higher among exposed than among non exposed (35% vs 10% and 45% vs 14%, respectively). The ANOVA Boniferroni test showed a significant difference in mean FENO between stone cutters and none exposed (P = 0.005). Conclusions: This study suggests the strong association between working as a stone cutting and shaping with respiratory inflammation. There is a need for respiratory mask type P2 use to protect workers from the exposure. There is also need for the follow up study involving cohorts of all workers happened to be in the mine.