Respirable Coal Dust Research Articles

Hazard and pollution characteristics of rock-containing dust in coal mine tunneling faces based on experimental and numerical study

The rock-containing dust poses a serious threat to the safe and efficient operation of coal mine tunneling faces (CMTFs). This study investigates the hazard and pollution characteristics of rock-containing dust in CMTFs by testing wettability, lithology surface functional groups, and particle size distribution of dusts with varying rock content. Furthermore, the spatial and temporal evolution of rock-containing dusts is explored through CFD simulation and the effects of rock-containing dust on the dedusting characteristics of water spray are analyzed. The results show that the crystallinity exhibits an exponential growth trend as the mudstone content increases, and the respirable dusts < 2.5μm and < 7μm increase by 15.04 % and 24.28 %, respectively. The rock-containing dust reaches the end of the simulated tunnel in just 50 seconds. On both the driver’s and pedestrian’s sides, the dust concentration shows an approximate S-shaped increase over time. Under the condition that only traditional water spraying measures are implemented, the concentration of respirable rock-containing dust will be approximately 1.2–1.5 times higher than the concentration of respirable coal dust. The results have provided valuable insights into the hazard and pollution characteristics of rock-containing dust in CMTFs, which are crucial for guiding dust disaster management in coal mines.

In vitro toxicity assessment of bioavailable iron in coal varieties of Central India

Introduction Information on bioavailable Iron (BAI) content in respirable coal dust (RCD) is crucial to address occupational health and safety, especially in preventing coal workers’ pneumoconiosis (CWP). Materials and methods In the present study, we determined BAI concentrations in seventy-seven coal samples collected from ten coal mining regions of Central India. The cytotoxic potential of BAI-RCD was established invitro by using alveolar epithelial (A549) and macrophage (U937) cell lines. The oxidative/antioxidant status, inflammations, and genotoxicity attributed to BAI-RCD exposure were evaluated and correlated with CWP pathophysiology. Results The mean BAI concentrations in the coal samples (n = 77) range from (275 to 9065 mg kg-1) and showed wide variability. Both cell lines were exposed to low (275 mg kg-1), moderate (4650 mg kg-1), and high (9065 mg kg-1) BAI-RCD samples showed significant (p &lt; 0.001) cytotoxicity in a dose-dependent manner (low &lt; moderate &lt; high) compared to the control. After BAI-RCD treatment, both cell lines showed a decrease in antioxidant stress measures (SOD, CAT, and GSH) and a significant (p &lt; 0.001) increase in oxidative stress parameters (NADPH, MPO, LPO, and PC). Furthermore, these cell line models demonstrated a statistically significant (p &lt; 0.001) dose-dependent increase in cytokines (TGF-β1, IL-1β, TNF-α, MCP-1, and IL-6 cytokines) and oxidative DNA damage marker (8-OH-dG). Conclusion Results indicated that the central India coals (even at low BAI content) may be accountable for inflammatory responses and cytotoxicity. Hence, BAI can be important characteristic to establish safety standards for coal dust exposure before active mining.

An evaluation of pyrite as a component of respirable coal dust

Over the past two decades, the rise in coal worker’s pneumoconiosis has prompted research into the effects of respirable coal dust components. This study explores how coal-pyrites produce hydroxyl radicals (•OH), a reactive oxygen species closely associated with particle toxicity, and assesses the ability of safe chemical additives to reduce •OH production at various pH levels. Promising candidates were evaluated in various solutions, including tap and process waters and simulated lung fluid. We employed electrokinetic measurements, infrared and X-ray photoelectron spectroscopies, and ab initio atomistic simulations to analyze particle surfaces. The study also looked at how surface aging affects •OH production. Our results show that •OH generation of the pyrite varies and is catalyzed by elements like silicon, aluminum, and iron in pyrite. Carboxymethyl cellulose was effective in reducing •OH production by targeting surface sulfide and silicon sites and affecting surface hydration and charge. Atmospheric aging was found to increase •OH production, especially in the pyrite with high iron and silicon and low calcium contents, relative to other samples. This highlights the role of the pyrite surface properties and chemical composition, and the solution pH and composition in •OH generation by coal-pyrites.

Kinetics-based wetting properties of microdroplets impacting respirable coal dust particles

The removal of respirable coal dust particles has been the focus of domestic and foreign research, and the spray dust suppression technology has been adopted for the prevention and control process; it is based on the mechanism whereby liquid droplets impact dust particles. To further study the wetting properties of microdroplets impacting respirable coal dust particles based on kinetics, this study focused on the droplet morphology, and mathematical and physical models of a microdroplet impacting a respirable coal dust particle were established to explore the variation laws of the droplet spreading and wetting under central and non-central impacts, for which the CLSVOF numerical simulation approach was adopted. The results showed the occurrence of gas retention at the phase interface, which affected the droplet wetting characteristics on the coal dust surface, after the contact between the liquid and dust particles. The influence of the impact velocity, particle size ratio, contact angle, and offset distance on the droplet spreading behavior was investigated by comparative analysis of 12 working conditions with different parameters. The droplets can completely wrap the coal dust particles under only one working condition parameter (V = 5m/s,Φ = 2,θ = 90°,L = 0 μm). The microdroplets are extremely difficult to wet respirable coal dust particles and the spreading behavior of the final droplet could be divided into three states: static adsorption, complete encapsulation and permanent escape. Our results can help better understand the wetting relationship between microdroplets and respirable coal dust particles, serving as a basis for dust prevention and control.

Comparison and analysis research on occupational exposure limits of coal dust between China and foreign countries

Objective: To study and compare the occupational exposure limits (OELs) of coal dust between China and foreign countries, understand the OEL of coal dust in China, and provide data and basis for revising the OEL of coal dust in China. Methods: In August 2023, by searching the official websites of limits setting institutions in relevant countries and regions at home and abroad, collecting and sorting out the OELs of coal dust issued by 10 limit setting institutions in 6 countries and the background information of the formulation, and conducting specific analysis on the classification, limit level and formulation principles of coal dust OEL in each country/institution. Results: In China and Japan, the total dust and respirable dust of coal dust OEL were established respectively, while in other countries, only the time-weighted average concentration (TWA) of respirable coal dust exposure was established. The TWA prescribed by China's Notional Health Commission, the United States Occupational Safety and Health Administration (OSHA) , the United States Mining Safety and Health Administration (MSHA) and the Australian Safety Work Bureau when the SiO(2) content was less than 5% were 5, 2.4, 2 and 3 mg/m(3) respectively. China GBZ 2.1-2019 sets the limit of 2.5 mg/m(3) for respirable coal dust with SiO(2) content less than 10%. The TWA set by the American Conference of Government Industrial Hygienists (ACGIH) and the South African Department of Mines and Energy (DME) for anthracite coal were 0.4 and 0.8 mg/m(3), respectively, and bituminous coal or lignite were 0.9 and 1.8 mg/m(3), respectively. The respirable coal dust TWA set by the National Institute for Occupational Safety and Health (NIOSH) in the United States was 1 mg/m(3), and the TWA set by the New Zealand Work Safety Authority was 3 mg/m(3). Conclusion: At present, the OEL of coal dust in China is at a relatively loose level, and it is suggested to further explore the possibility of revising coal dust OEL.

Development and evaluation of an immersive VR-CFD-Based tool for dust exposure mitigation in underground tunnelling operations

Long-term exposure to respirable coal and silica dust during underground tunnelling operations has gained increasing attention in recent years. The solution to effective mitigation of dust exposure depends not only on higher-order engineering controls, but also on administrative controls for frontline workers. However, there is a disconnect between knowledge gathered in the field of dust exposure monitoring and the frontline worker, resulting in important learnings being overlooked in underground tunnelling operations. To remedy this discrepancy, an immersive educational tool was developed to visualise computational fluid dynamics (CFD) modelling datasets of ventilation and respirable dust flow characteristics in the tunnel face in a virtual reality (VR) environment. An algorithm was developed for processing the large and complex CFD datasets into a form that can be processed and visualised using standalone VR headsets with limited processing power. The VR-CFD system was assessed by an industry expert and via many industry showcases, where regular feedback was received for making significant improvements in this education tool. This tool has been developed as a training platform to allow frontline workers to better understand the results of decisions made during tunnelling operations and the best practices for dust controls. A number of key technological achievements were made that can be used in the future to quickly translate real-world particulate readings collected from underground space into a VR visualiser. This VR-CFD digital technology can readily be extended to mining, construction and other tunnelling operations in the underground space, thus improving health and safety.

Wearable Resonator-Based Respirable Dust Monitor for Underground Coal Mines

Exposure to respirable coal dust and diesel exhaust in underground coal mines can cause detrimental airway diseases such as coal worker’s pneumoconiosis (CWP), silicosis, and lung cancer. In this article, we present the design, fabrication, and experimental evaluation of a low-cost wearable respirable dust monitor (WEARDM) that uses a dual-resonator gravimetric sensing approach for real-time measurement of respirable airborne particulate matter (PM) concentrations. The sensor selects for the ISO-respirable dust fraction using a miniature virtual impactor (VI) and removes moisture from the collected dust to ensure accurate mass measurement. WEARDM uses a novel dual-resonator mass sensor (DRMS) that is composed of a quartz crystal microbalance (QCM) and a film bulk acoustic resonator (FBAR). The QCM measures the mass concentration of particles generated from coal mining operations [typically >2.5- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> aerodynamic diameter (AD)], separated using inertial impaction. Thermophoretic precipitation is used to deposit the fine and ultrafine particles, such as those emitted from diesel sources [typically <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$ &lt; 0.1~\mu \text{m}$ </tex-math></inline-formula> AD) on FBAR. This allows the WEARDM system to maintain a large dynamic range and uniform collection efficiency (CE) across the entire respirable fraction. The WEARDM system is optimized for a low flow rate of 250 mL/min which results in low power usage and a small form factor and is an order of magnitude smaller and less expensive than currently available devices.

Comparative 6+studies of environmentally persistent free radicals on nano-sized coal dusts

Coal dust is the major hazardous pollutant in the coal mining environment. Recently environmentally persistent free radicals (EPFRs) were identified as one of the key characteristics which could impart toxicity to the particulates released into the environment. The present study used Electron Paramagnetic Resonance (EPR) spectroscopy to analyze the characteristics of EPFRs present in different types of nano-size coal dust. Further, it analyzed the stability of the free radicals in the respirable nano-size coal dust and compared their characteristics in terms of EPR parameters (spin counts and g-values). It was found that free radicals in coal are remarkably stable (can remain intact for several months). Also, Most of the EPFRs in the coal dust particles are either oxygenated carbon centered or a mixture of carbon and oxygen-centered free radicals. EPFRs concentration in the coal dust was found to be proportional to the carbon content of coal. The characteristic g-values were found to be inversely related to the carbon content of coal dust. The spin concentrations in the lignite coal dust were between 3.819 and 7.089 μmol/g, whereas the g-values ranged from 2.00352 to 2.00363. The spin concentrations in the bituminous coal dust were between 11.614 and 25.562 μmol/g, whereas the g-values ranged from 2.00295 to 2.00319. The characteristics of EPFRs present in coal dust identified by this study are similar to the EPFRs, which were found in other environmental pollutants such as combustion-generated particulates, PM2.5, indoor dust, wildfires, biochar, haze etc., in some of the previous studies. Considering the toxicity analysis of environmental particulates containing EPFRs similar to those identified in the present study, it can be confidently hypothesized that the EPFRs in the coal dust might play a major role in modulating the coal dust toxicity. Hence, it is recommended that future studies should analyze the role of EPFR-loaded coal dust in mediating the inhalation toxicity of coal dust.

Differences in the characteristics and pulmonary toxicity of nano- and micron-sized respirable coal dust

BackgroundThe characteristics of coal dust (CD) particles affect the inhalation of CD, which causes coal worker’s pneumoconiosis (CWP). CD nanoparticles (CD-NPs, < 500 nm) and micron particles (CD-MPs, < 5 μm) are components of the respirable CD. However, the differences in physicochemical properties and pulmonary toxicity between CD-NPs and CD-MPs remain unclear.MethodsCD was analyzed by scanning electron microscopy, Malvern nanoparticle size potentiometer, energy dispersive spectroscopy, infrared spectroscopy, and electron paramagnetic resonance spectroscopy. CCK-8 assay, ELISA, transmission electron microscope, JC-1 staining, reactive oxygen species activity probe, calcium ion fluorescent probe, AO/EB staining, flow cytometry, and western blot were used to determine the differences between CD-NPs and CD-MPs on acute pulmonary toxicity. CCK-8, scratch healing and Transwell assay, hematoxylin–eosin and Masson staining, immunohistochemistry, immunofluorescence, and western blot were applied to examine the effects of CD-NPs and CD-MPs on pneumoconiosis.ResultsAnalysis of the size distribution of CD revealed that the samples had been size segregated. The carbon content of CD-NPs was greater than that of CD-MPs, and the oxygen, aluminum, and silicon contents were less. In in vitro experiments with A549 and BEAS-2B cells, CD-NPs, compared with CD-MPs, had more inflammatory vacuoles, release of pro-inflammatory cytokines (IL-6, IL-1β, TNFα) and profibrotic cytokines (CXCL2, TGFβ1), mitochondrial damage (reactive oxygen species and Ca2+ levels and decreased mitochondrial membrane potential), and cell death (apoptosis, pyroptosis, and necrosis). CD-NPs-induced fibrosis model cells had stronger proliferation, migration, and invasion than did CD-MPs. In in vivo experiments, lung coefficient, alveolar inflammation score, and lung tissue fibrosis score (mean: 1.1%, 1.33, 1.33) of CD-NPs were higher than those of CD-MPs (mean: 1.3%, 2.67, 2.67). CD-NPs accelerated the progression of pulmonary fibrosis by upregulating the expression of pro-fibrotic proteins and promoting epithelial–mesenchymal transition. The regulatory molecules involved were E-cadherin, N-cadherin, COL-1, COL-3, ZO-1, ZEB1, Slug, α-SMA, TGFβ1, and Vimentin.ConclusionsStimulation with CD-NPs resulted in more pronounced acute and chronic lung toxicity than did stimulation with CD-MPs. These effects included acute inflammatory response, mitochondrial damage, pyroptosis, and necrosis, and more pulmonary fibrosis induced by epithelial–mesenchymal transition.

Characterization of deposited dust and its respirable fractions in underground coal mines: Implications for oxidative potential-driving species and source apportionment

Oxidative potential (OP) is considered to be an efficient indicator of particulate matter (PM) to induce oxidative stress in the lungs and is increasingly considered to be a relevant health metric. In this study, two complementary OP assays were deployed, including dithiothreitol (DTT) and ascorbic acid (AA) assays, to investigate the potential toxicity (as generators of oxidative stress) of respirable fractions (DD4, < 4 μm) of deposited dust (DD500, < 500 μm) in underground low-S and low-pyrite coal mines in Henan Province, Central China. The OPDTT of DD4 is higher than that reported for other types of atmospheric PM, whereas the OPAA of DD4 is similar and/or slightly higher. Cross-correlation and multilinear regression analyses are applied using datasets of major mineral and geochemical patterns in the DD4 samples and the respective OP values to identify the major drivers for OP in respirable coal dust. Thereafter, the patterns of DD4 are compared with those of DD500 and the parent coals to determine the sources of OP-relevant substances. OPDTT is mainly governed by some trace elements (Sb, As, Li, B, Sr, and Pb) and minor minerals (anatase, quartz, siderite), and their synergistic effect may be one of the reasons for the high DTT consumption. For OPAA, quartz, total clay (sum of illite, kaolinite, tobelite, and clinochlore) and Ni, Cr, Co, Si, and S, play an important role in regulating the OPAA of pyrite-free DD4 samples. These OP-relevant substances have three sources: coal dust, which has a similar composition in DD4, DD500, and the parent coal (such as siderite and its associated elements); gangue dust, which does not occur in the parent coal but is widely detected in DD4 and DD500 (such as quartz, kaolinite, and relevant elements); and cement dust (from gunite galleries), which is mainly calcite- and calcite-associated elements.

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, DD500). 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 DD500, probably due to relatively lower levels of organic matter. Mass concentrations of all elements observed in this study remained below occupational exposure limits.

Characterization of nano-to-micron sized respirable coal dust: Particle surface alteration and the health impact

Chemical and physical properties of coal dust particles significantly influence the inhalation of respirable coal dust by miners, causing several lung diseases such as coal workers’ pneumoconiosis (CWP) and silicosis. Multiple experimental techniques, including proximate/ultimate analyses, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), laser diffraction, and low-pressure CO2 and N2 adsorption, were used to investigate the chemical and physical properties of micron-/nano-coal particles comprehensively. Compared to the micron-scale coal dust, the nano-coal dust (prepared by cryogenic ballmill) shows the increase of carbon content and aromaticity and a decrease of oxygen content along with the reduction of oxygen-containing functional groups. Pore volume and surface area estimated by low-pressure CO2 and N2 adsorption have more than five-time increase for the nano-coal dust. The reduction of oxygen functional groups suggests the dropped wetting behavior of coal nanoparticles. The significantly increased pore volume and surface area in coal nanoparticles could be caused by the enhanced pore interconnectivity on the particle surface and the alteration of coal macromolecules. Weaker wettability and the highly enhanced surface area suggest potentially more significant toxicity of nano-coal dust inhaled by coal miners.

A Laboratory Investigation of Underside Shield Sprays to Improve Dust Control of Longwall Water Spray Systems

Researchers at the National Institute for Occupational Safety and Health (NIOSH) performed laboratory testing to improve longwall dust control by examining the use of underside shield sprays in conjunction with the longwall directional spray system. In a field survey of longwall operations, NIOSH researchers observed dust clouds created by the fracturing and spalling of coal immediately upwind of the headgate drum that migrated into the walkway, exposing mining personnel to respirable coal dust. The goal of this research was to create an effective traveling water curtain to prevent this dust from reaching the personnel walkway by redirecting it toward the longwall face. The location, orientation, and pressure of the water sprays were the primary testing parameters examined for minimizing dust exposure in the walkway. Laboratory testing indicates that the use of underside shield sprays on the longwall face may be beneficial toward reducing respirable dust exposure for mining personnel.

Physico-chemical properties and reactive oxygen species generation by respirable coal dust: Implication for human health risk assessment

This study investigates the mineralogy, micro-morphology, chemical characteristics and oxidation toxicity of respirable dusts generated in underground coal mines. The active sampling was applied to collect airborne particulates with aerodynamic diameter <4 µm (PM4) at depth greater than 500 m from earth surface. The average mass concentration of PM4 was extremely higher than recommended values. QXRD and FESEM-EDS analyses were applied to study the micro-mineralogy and micro-morphology of respirable dusts. The chemical analysis by ICP-MS revealed an enrichment of V, Cr, Cu, Zn, As, Ag, Cd and Sb in respirable dust compared with the background environment and world coals. The EPA’s health risk model showed that the health risk posed by Cr and Co in all workplaces exceeded the acceptable risk value for human health. The synthetic respiratory tract lining fluid (RTLF) model was utilized to achieve a novel insight into the toxicity of respirable coal dust. The result showed an overall depletion of lung surface antioxidants with the decreasing trend of ascorbic acid > reduced glutathione >> urate, implying low- to medium level of oxidative stress. The result of this study can be applied globally by decision-makers to decrease hazardous exposure of mine workers to respirable dust.

Experimental Research and Numerical Simulation of Ejector Precipitator in a Fully Mechanized Mining Face

In order to effectively reduce the coal dust concentration in a fully mechanized mining face, this research used laboratory experiment, numerical simulation, and field test to conduct an in-depth exploration of the ejector precipitator installed at the low-level caving coal hydraulic support. Firstly, through the experimental platform in the laboratory, the dust removal effect of the nozzle with different structural parameters was tested, and the 3D particle dynamic analyzer was adopted to verify its atomization characteristics; then, the structural parameters corresponding to the nozzle in the best test results were obtained. Secondly, by using Fluent, the negative pressure flow field in the ejector barrel was numerically simulated. The results indicated that when the pressure of supply water was 12 MPa, the negative pressure value formed in the flow field was the lowest and the inspiratory velocity was the largest, which was conducive to dust removal. Finally, the tests of liquid–gas ratio and dust removal ratio were carried out in a fully mechanized mining face. The results showed that when the nozzle specification recommended by the experiment and the pressure of supply water recommended by the numerical simulation were used, the removal ratios of the total coal dust and the respirable coal dust were 89.5% and 91.0%, respectively, at the measuring point of the highest coal dust concentration. It indicates that the ejector precipitator has a good application effect in reducing the coal dust concentration in a fully mechanized mining face and improving the work environment of coal mine workers.

The Impact of Black Lung and a Methodology for Controlling Respirable Dust.

Coal workers' pneumoconiosis (CWP), commonly known as black lung, is caused by the inhalation of respirable coal mine dust and is a disabling and potentially fatal lung disease with no cure. Historically, CWP has taken a tremendous human and financial toll in the US coal mining industry. Recent health surveillance data indicates that CWP continues to occur at elevated levels. Respirable coal dust exposure must be controlled to prevent the development of CWP. The Pittsburgh Mining Research Division of the National Institute for Occupational Safety and Health (NIOSH) conducts laboratory and mine-site research to identify control technologies that can be used to successfully reduce respirable dust levels. Various technologies, using multiple methods of control, can be applied in order to reduce dust levels. An overview of CWP's impact and a general methodology for controlling respirable dust in underground coal mines are discussed in this paper.

Dose-response relationship between different respirable coal dust exposures and pneumoconiosis risk

Objective: To investigate the dose-response relationship between the cumulative dust exposures to anthracite, bituminous coal, and lignite and the cumulative prevalence rates of pneumoconiosis due to the exposures, respectively and provide a basis for scientific development of occupational health standards. Methods: Investigation on the exposure to coal dust and pneumoconiosis prevalence was conducted in 9 state-owned coal mines. The cumulative anthracite, bituminous coal, and lignite dust exposure specific cumulative prevalence rates of pneumoconiosis were calculated by life table method, respectively. The linear regression equations were used to control the unilateral interval to obtain the exposure concentration limits of the respirable coal dust, respectively. Results: A total of 21 000 coal miners in the 9 coal mines were included in the study. The detection rates of pneumoconiosis in coal miners in anthracite, bituminous coal and lignite mines were 11.27%, 21.32%, and 6.00%. The average lengths of exposure to coal dust at pneumoconiosis onset were 20.12 years, 22.88 years, and 25.21 years, respectively and the dose-response relationships between the cumulative respirable coal dust exposure and the cumulative prevalence rates were all linear regression equations, which are y=5.788x-16.043 (R(2)=0.949), y=5.679x-16.837 (R(2)=0.904), and y=6.465x-19.573 (R(2)=0.944), respectively. Supposing that the safety coefficient is 1.2, when the cumulative prevalence rate of pneumoconiosis after 30 years of exposure to dust is not higher than 1%, the exposure concentration limits of the three types of respirable coal dust are 1.7, 2.3, and 3.9 mg/m(3), respectively. Conclusions: The results of this study shows that the detection rate of pneumoconiosis, the average length of exposure to coal dust at pneumoconiosis onset, and the exposure concentration limits of the respirable coal dust varied with coal types. In the case of the same cumulative level of coal dust exposure, the lower the coal volatiles is (i.e. the higher the carbon content is), the higher the cumulative prevalence rate of pneumoconiosis is (anthracite>bituminous coal>lignite). It is suggested to develop national occupational health standards of coal dust exposure according to the grades of coal.

Dose-response relationship analysis between cumulative coal dust exposure and pneumoconiosis risk

Objective: To explore the dose-response relationship between the cumulative coal dust exposure and the cumulative prevalence rate of pneumoconiosis among the coal miners, and to provide a basis for the revision of exposure concentration limits standards of the respirable coal dust and the total dust. Methods: A retrospective cohort study was conducted to study the coal miners in 11 state-owned coal mines from January to August 2013. 21000 coal miners in the 9 coal mines were adopted in the furthre study after the bias treatment.The occupational health records of coal miners from the date of coal production to the end of 2012 in each coal mine were collected. Based on the cumulative dust exposure group of the respirable coal dust and that of the total dust, both the miner's cumulative prevalence rate of pneumoconiosis were calculated by the life table method respectively. The dose-response relationship between the cumulative coal dust exposure and pneumoconiosis risk was established (subject to logistic regression model) . Assuming the cumulative prevalence rate is not higher than 1% after 30 or 25 years of exposure to coal dust and the safety factor is 1.2, the exposure concentration limits of the respirable coal dust and the total dust were calculated by the logistic regression equations with one-sided interval statistical control. Results: There were 3224 pneumoconiosis patients (15.35%) altogether. The dose-response relationship between the cumulative respirable coal dust exposure and the cumulative prevalence rate of pneumoconiosis is a logistic regression equation logistic(r)=5.649lgDr-16.573 (R(2)=0.925) , and the legistic regression equation for the total dust, is logistic(t)=5.712lgDt-18.767 (R(2)=0.897) . When the prevalence rate of pneumoconiosis after 30 years of exposure to coal dust is not higher than 1%, the exposure concentration limits of the respirable coal dust and that of total dust contact are 2.2 mg/m(3) and 4.8 mg/m(3), which are similar to those of national occupational health standards of China (2.5 mg/m(3) and 4 mg/m(3)) . When the prevalence rate of pneumoconiosis after 25 years of exposure to coal dust is not higher than 1%, the exposure concentration limits of the respirable coal dust is 2.7 mg/m(3). Conclusion: It is recommended to strictly implement the current national occupational health standard and abolish the relevant safety production industry standard.

Air Pollution Emissions 2008-2018 from Australian Coal Mining: Implications for Public and Occupational Health.

Occupational exposure limits for respirable coal dust are based on exposure during working hours, but coal miners may experience additional community-based exposures during nonworking hours. We analyzed Australia National Pollutant Inventory (NPI) data for the years 2008–2018 to estimate air pollutants (metals, nitrogen oxides, particulate matter ≤ 10 micrometers (PM10) and ≤2.5 micrometers (PM2.5)) originating from coal mines. PM10 levels from community-based air monitors in Queensland and New South Wales were also compared between mining and nonmining communities. Results indicated that tons of coal mined increased over the study period, and that levels of particulate matter, metals, and nitrogen oxides increased significantly over time as well. Coal mines accounted for 42.1% of national PM10 air emissions from NPI sites. PM2.5 from coal mines accounted for 19.5% of the national total, metals for 12.1%, and nitrogen oxides for 10.1%. Coal mining occurred in 57 different post codes; the 20 coal-mining post codes with the highest PM10 emissions were home to 160,037 people. Emissions of all studied pollutants were significantly higher from coal mining sites than from other types of NPI sites. Results from community-based air monitoring stations indicated significantly higher population PM10 exposure in coal mining communities than in nonmining communities. The health of the public at large is impacted by coal mining, but to the extent that miners also live near coal mining operations, their total exposure is underestimated by consideration of exposure only during working hours.

Experimental investigation on wetting mechanism for coal dust with different metamorphic degree based on infrared spectrum and 13C‐NMR

Respirable coal dust accounts for heart and respiratory diseases of coal miners such as asthma, pneumoconiosis, and black lung disease. What is more, coal dust explosion seriously affects coal mine safety production and coal miners' life safety. Generally, dust suppressants are commonly applied in coal mines. However, current dust suppressants are not working effectively. To develop a better dust suppressant, we attempt to explore the factors affecting the wettability of coal dust under different metamorphic levels from the essence of coal dust wetting mechanism in this paper. Specifically, we use Fourier transform infrared (FTIR) spectroscopy and nuclear magnetic resonance (NMR) to reveal the microstructure of coal from two aspects of functional group and carbon skeleton structure and obtain the micro information of the surface functional group types, quantity, and carbon structure of coal with different degrees of metamorphism, as well as the change rule of functional group of coal sample with coal rank and the law of carbon increase and deoxidization of coal metamorphism. After that, we acquired the structural parameters of coal by the NMR experiments and fitted the quantitative mathematical relationship between the microstructure parameters and wettability of coal through SPSS and ORIGIN software. Finally, this paper constructs an evaluation model for the influencing factors of coal dust wettability, explains the influence degree of different coal dust structure on coal dust wettability, improves the coal dust wettability mechanism, and provides more quantitative research ideas and methods for the control of coal dust.