How relevant are engineering samples in the management of personal dust exposure?

A directive, legislated by the South African Department of Minerals and Energy(DME) in 1997, was introduced to reduce the dust exposures of continuous miner(CM) operators to below 5 mg/m3, when measured at the operator's cab position. The focus of this paper is to review the effectiveness of observing this rule for almost two decades and discuss industry perceptions arising from the application of this rule. The results have demonstrated that the engineering sample cannot predict the personal shift dust exposure of a CM operator. Therefore, it is recommended that the engineering sampling, as currently practiced,should be reviewed with the objective to discontinue and replace it by the approved PDM3700 realtime dust monitor.

Chemistry and particle size distribution of respirable coal dust in underground mines in Central Eastern Europe

Despite international efforts to limit worker exposure to coal dust,it continues to impact the health of thousands of miners across Europe.Airborne coal dust has been studied to improve risk models and its control to protect workers.Particle size distribution analyses shows that using spraying systems to suppress airborne dusts can reduce particulate matter concentrations and that coals with higher ash yields produce finer dust.There are marked chemical differences between parent coals and relatively coarse deposited dusts(up to _(500)μm,DD_(500)).Enrichments in Ca,K,Ba,Se,Pb,Cr,Mo,Ni and especially As,Sn,Cu,Zn and Sb in the finest respirable dust fractions could originate from:(i)mechanical machinery wear;(ii)variations in coal mineralogy;(iii)coal fly ash used in shotcrete,and carbonates used to reduce the risk of explosions.Unusual enrichments in Ca in mine dusts are attributed to the use of such concrete,and elevated K to raised levels of phyllosilicate mineral matter.Sulphur concentrations are higher in the parent coal than in the DD_(500),probably due to relatively lower levels of organic matter.Mass concentrations of all elements observed in this study remained below occupational exposure limits.

Respirable Dust and Respirable Crystalline Silica Concentration in Workers of Copper Mine, Mongolia

Introduction: Prosperity in the mining industry in Mongolia has led to an increase in the number of mining workers, resulting in an increase in occupational exposures and the prevalence of occupational diseases and disabilities. The aim of this study was to assess the personal exposure of workers to respirable dust (RD) and respirable crystalline silica (RCS). Method: A cross-sectional study was conducted at the Erdenet Copper Ore Mining and included 581 personal samples of RD and 324 samples of RCS, collected in 2018-2020. Results: The study results revealed that the geometric mean (GM) of RD was 0.35 mg/m3 (95% CI 0.32 - 0.39). The RD concentration in 5.9% (n = 34) of all the samples exceeded the permissible exposure level (PEL) (3 mg/mg3). The GM of RCS was 0.012 mg/m3 (95% CI 0.010 - 0.016). In total, 12.0% (n = 39) of all RCS sample concentrations exceeded the PEL (0.1 mg/m3). Conclusion: Steel smelters, blasters, welders, and maintenance laborers were exposed to RD, while crushers, operators, drilling machinists, and maintenance laborers were exposed to RCS. Therefore, regular monitoring of the work environment, risk-based health examinations for dust-exposed workers, efficient support for dust mitigation, reduction measures at the source, and engineering controls are needed.

Retinal nerve fiber layer thickness and retinal vascular caliber alterations in coal miners in northern China:a community-based observational study

AIM:To evaluate retinal nerve fiber layer thickness and retinal vascular caliber alterations in coal mine workers.METHODS:The community-based observational crosssectional study included 4004 participants of a subpopulation of the Kailuan Study.All the study participants underwent structured interviews with a standardized questionnaire,fundus photography and spectral-domain optical coherence tomography(OCT)examinations performed by trained doctors.RESULTS:The retinal nerve fiber layer thickness was significantly higher(P=0.006)and the central macular thickness was lower in coal miners(n=659,51.0±7.8 y)as compared to the control(working above the ground;n=477,51.8±7.5 y;P=0.032).Additionally,the downhole workers showed a significantly thicker retinal artery(P=0.012)and vein diameters(P<0.001).In multivariable regression,a thicker retinal nerve fiber layer was associated with a higher cumulative silica dust exposure(P=0.005)after adjusting for younger age and larger spherical equivalent.In a reverse pattern,a higher cumulative silica dust exposure(P=0.004)was significantly associated with a thicker retinal nerve fiber layer after adjusting for age,high-density lipoproteins and uric acid.Wider retinal vein diameters were associated with higher cumulative silica dust exposure(P=0.036)after adjusting for younger age and larger spherical equivalent.CONCLUSION:The retinal vessels diameters and retinal nerve fiber layer thickness are significantly thicker in long term of coal mining.The results of our study indicate that underground working environment may lead to retinal vessel dilation and inflammation.Thus,ocular examination might be needed within coal miners in order to monitor the occupational eye health as well as the incidence and progression of eye diseases.