ABSTRACT
OBJECTIVE: To analyze the hazardous status of respiratory dust in coal mining enterprises. METHODS: A total of 20 coal mining enterprises in a mining group were selected as the research subjects using a cluster random sampling method. Respiratory dust in the workplace was detected, and the incidence of pneumoconiosis was investigated. RESULTS: The dust types in the workplace of these 20 coal mining enterprises were mainly coal dust and silica dust. The posts with serious coal dust hazard were coal mining and tunneling posts. The M(P_0-P_(100)) of the exposure concentration of time weighted average(C_(TWA)) were 2.38(0.19-14.21) and 2.73(0.49-9.57) mg/m~3. The over-standard rate was 49.2% and 50.0%, respectively, that was higher than the post of gangue selection(all P<0.05 or all P<0.017). The results of short time exposure concentration of short term(C_(STE)) and the over-standard rate were higher in the coal mining and tunneling posts than those of gangue selection and boiler room post(all P<0.05 or all P<0.008). The most serious post with silica dust hazard was the tunneling post, and the M(P_0-P_(100))of C_(TWA) was 1.30(0.38-8.50) mg/m~3, and the over-standard rate was 85.7%. The detection results and over-standard rate of C_(STEL) were higher in the coal mining and tunneling posts than that of boiler room post(all P<0.01). The coal dust over-standard rate of C_(TWA) in workplaces of coal mining enterprises increased from 2015 to 2018(P<0.05). However, there was no significant difference in the over-standard rate of silica dust C_(TWA) in different years(P>0.05). From 2015 to 2018, the incidence of pneumoconiosis was 0.3%, 0.3%, 0.2% and 0.3% respectively, and the patients were all from coal mining and tunneling posts. CONCLUSION: The supervision, management and treatment of respiratory dust hazard in coal mining and tunneling posts should be strengthened to protect the health of workers.
ABSTRACT
Objective@#To grasp the present situation of occupational hazards of coal dust in our country, understand our country coal dust workers' occupational health risks, provide information based on evidence and analysis for the government and organize to effectively deal with the current status of high coal workers pneumoconiosis incidence in China, and protect coal dust workers' occupational health. @*Methods@#The research object is the " mining-transportation-use" of coal industrial chain, referring to 33 units. Use field investigation to obtain the coal dust exposure, dust prevention measures and the occupational health data of study object. Use quantitative evaluation method of International council on mining and metals occupational health risk assessment model (ICMM method) and occupational hazard risk index method (index method) , with coal workers pneumoconiosis as health outcomes, to evaluate the coal dust occupational health risks of coal industrial chain. @*Results@#The free silica content of partial coal dust in China is more than 10%, and even to 19.5%. coal dust concentration in workplaces, such as excavating system of dust coal mining (total dust: 22.1~46.5 mg/m3, respiratory dust: 8.4~17.7 mg/m3) , dumper (total dust: 25.2 mg/m3, respiratory dust: 6.9 mg/m3) , transfer tower (total dust: 35.4 mg/m3) of coal transportation and belt coal plough device of coal use (total dust: 36.3 mg/m3, respiratory dust: 14.0 mg/m3) , are much higher than those in other workplaces, and coal dust concentration of workers in these places (2.6~9.3 mg/m3) are much higher than those in other places, which are statistically significant. ICMM method evaluation results show that the risk value of excavating system is between 504~1 089, and the risk value of comprehensive mining system is between 347~2 040, which are far statistically significant higher than that of other systems. Index method evaluation results (excavating system risk value between 3.1~9.7, fully mechanized system risk value between 3.7~9.3) , are basically identical with ICMM method (correlation coefficient r=0.857, P<0.01) . The new cases of coal worker pneumoconiosis are distributed in three post of coal mining, excavating and coal mine mixing. @*Conclusion@#Coal-dust hazards are widely distributed in the coal "mining, transportation, and use" industrial chain, which of the underground coal mine is as serious as intolerable, meanwhile the risk of other industrial chain is basically can tolerable. The high coal dust concentration and the high risk of coal dust occupational hazard are concentrated in the excavating system and the comprehensive mining system. It is recommended to start the study on risk assessment and risk response of coal dust health hazard at the national level, and the occupational exposure limit of coal dust should be established according to the content of free silica.
ABSTRACT
Objective@#To evaluate the applicability of quantitative grading method (GBZ/T 229.1-2010) and occupational hazard risk index method in coal dust occupational health risk assessment.@*Methods@#Taking 4 coal mines as the research object of risk assessment and making occupational health field testing and investigation. Based on two risk assessment methods, we analysed the health risk levels of 20 occupations which were exposed to coal dust in workplaces.@*Results@#Coal dust working post had different risk levels in 4 coal mines, the post of higher risk level were mainly concentrated in the underground workplace of coal mine, especially the post of coal mining and tunneling system. The two risk assessment results showed that the risk levels of coal-mining machine drivers and tunneling machine drivers were the highest. The risk levels of coal dust working post used by two risk assessment methods had no significant difference (P>0.05) and were highly correlated (r=0.821, P<0.001) . Evaluation results of two risk assessment methods were supported by the field investigation and literatures.@*Conclusion@#The two risk assessment methods can be used in coal dust occupational health risk assessment.
ABSTRACT
BACKGROUND: Surfactant-containing water sprays are commonly used in coal mines to collect dust. This study investigates the dust collection performance of different surfactant types for a range of coal dust particle sizes and charges. METHODS: Bituminous coal dust aerosol was generated in a wind tunnel. The charge of the aerosol was either left unaltered, charge-neutralized with a neutralizer, or positively- or negatively-charged using a diffusion charger after the particles were neutralized. An anionic, cationic, or nonionic surfactant spray or a plain water spray was used to remove the particles from the air flow. Some particles were captured while passing through spray section, whereas remaining particles were charge-separated using an electrostatic classifier. Particle size and concentration of the charge-separated particles were measured using an aerodynamic particle sizer. Measurements were made with the spray on and off to calculate overall collection efficiencies (integrated across all charge levels) and efficiencies of particles with specific charge levels. RESULTS: The diameter of the tested coal dust aerosol was 0.89 μm ± 1.45 [geometric mean ± geometric standard deviations (SD)]. Respirable particle mass was collected with 75.5 ± 5.9% (mean ± SD) efficiency overall. Collection efficiency was correlated with particle size. Surfactant type significantly impacted collection efficiency: charged particle collection by nonionic surfactant sprays was greater than or equal to collection by other sprays, especially for weakly-charged aerosols. Particle charge strength was significantly correlated with collection efficiency. CONCLUSION: Surfactant type affects charged particle spray collection efficiency. Nonionic surfactant sprays performed well in coal dust capture in many of the tested conditions.
Subject(s)
Aerosols , Coal , Diffusion , Dust , Particle Size , Water , WindABSTRACT
The phagocytic ability and fashion of two types of alveolar macrophages (AM) on coal dust were studied by differential interference contrast microscope, scanning electron microscope and image analyser. This study revealed the phagocytic ability of spherical AM on dust was higher than that of the flat AM. Both types of AM could extend long tenuous filopodia to the coal dusts around the cells. The coal dusts were attached to the cell surface and then were sunk into the macrophage. The amount of the phagocyted coal dusts per unit time were measured by image analytical method which is more exact than other methods. This paper provided not only a new approach for study phagocytosis of macrophage on inorganic dusts, but also some essential morphologic evidences for study of pneumoconiosis.