Characteristics Of Dust Research Articles

Explosion Flame and Pressure Characteristics of Nonstick Coal Dust and the Inhibition of Explosion Suppressants

Nonstick coal is widely distributed in the world and is an important resource for human beings. The explosion characteristics and explosion suppression of nonstick coal dust are increasingly concerning. In this paper, the flame and pressure characteristics of a nonstick coal dust explosion are studied, and the suppression effect of SiO2, KCl, and NH4H2PO4 on the explosion is analyzed. It is concluded that the maximum propagation distance of a nonstick coal dust explosion flame is 0.59 m, the maximum pressure is 0.63 MPa, and the maximum pressure rise rate is 40.79 MPa/s. The explosion suppression effect of SiO2 is worse than that of KCl, but the inhibition effect of NH4H2PO4 is the best among the three kinds of explosion suppressants. When the mass percentage of NH4H2PO4 dust mixed with coal dust is 70%, the coal dust explosion is completely suppressed. It absorbs a certain amount of heat to promote the chemical reaction, which plays a certain role in controlling the explosion process, and its explosion suppression mechanism includes both physical and chemical explosion suppression.

Examining the dust of the tailless Oort-cloud comet C/2020 T2

We report our latest analysis of the Oort-cloud comet C/2020 T2 (also named Palomar or T2) observed at 2.06 au from the Sun (phase angle of 28.°5) roughly two weeks before perihelion. It lacks a significant dust tail in scattered light, showing a strong central condensation of the coma throughout the apparition that is reminiscent of so-called Manx comets. Its spectral slope of polarized light increases and decreases in the J (1.25 μm) and H (1.65 μm) bands, respectively, resulting in an overall negative (blue) slope (−0.31 ±0.14% μm−1 ) in contrast to the red polarimetric color of active comets observed at similar geometries. The average polarization degree of T2 is 2.86±0.17% for the J and 2.75±0.16% for the H bands. Given that near-infrared wavelengths are sensitive to the intermediate-scale structure of cometary dust (i.e., dust aggregates), our light-scattering modeling of ballistic aggregates with different porosities and compositions shows that the polarimetric properties of T2 are compatible with low-porosity (~66%), absorbing dust aggregates with negligible ice contents on a scale of 10–100 μm (density of ~652 kg m−3). This is supported by the coma morphology of T2 which has a viable β (the relative importance of solar radiation pressure on dust particles) range of ≲10−4. The secular evolution of r-band activity of T2 from archival data reveals that the increase in its brightness accelerates around 2.4 au pre-perihelion, with its overall dust production rate that is about 100 times smaller than those of active Oort-cloud comets. We also found an apparent concentration of T2 and Manx comets toward ecliptic orbits. This paper underlines the heterogeneous nature of Oort-cloud comets, which may be investigated in the near future with dedicated studies of their dust characteristics.

Formation, distribution, and IR emission of dust in the clumpy ejecta of Type II-P core-collapse supernovae, in isotropic and anisotropic scenarios

Large discrepancies are found between observational estimates and theoretical predictions when exploring the characteristics of dust formed in the ejecta of a core-collapse supernovae. We revisit the scenario of dust production in typical supernova ejecta in the first 3000 days after explosion, with an improved understanding of the evolving physical conditions and the distribution of the clumps. The generic, nonuniform distribution of dust within the ejecta was determined and using that, the relevant opacities and fluxes were calculated. The dependence of the emerging fluxes on the viewing angle was estimated for an anisotropic, ellipsoidal geometry of the ejecta that imitate SN 1987A. We model the He core from the center to its outer edge as 450 stratified, clumpy, annular shells, uniquely identified by their distinct velocities and characterized by their variations in abundances, densities, and gas and dust temperatures. We find that the formation of dust starts between day 450 and day 550 post-explosion, and it continues until about day 2800, although the first 1600 days are the most productive. The total dust mass evolves from ~10−5 M⊙ at day 500 to 10−3 M⊙ at day 800, finally saturating at about 0.06 M⊙. The masses of the O-rich dust (silicates, alumina) dominates the C-rich dust (amorphous carbon, silicon carbide) at all times; the formation of carbon dust is delayed beyond 2000 days post-explosion. We show that the opacities are largest between days 800 and 1600, and the characteristic spectral features of O-rich dust species are suppressed at those times. The fluxes emerging along the smallest axes of the ellipsoidal ejecta are found to be the most obscured, while a viewing angle between 16 to 21° with that axis appears to be in best agreement with the fluxes from SN 1987A at days 615 and 775.

Study on the preparation of green suppressors and their characteristics in coal dust flame propagation inhibition

The properties of a green waste molecular sieve-based powder suppressor in inhibiting the flame propagation of coal dust were studied. Waste molecular sieve (S) was pretreated and selected as the carrier, potassium oxalate (K) and ferric citrate (T) as the active components. The reverse dissolution crystallization method was adopted and S@K/T, S@T/K, S@ T -K suppressors with different core–shell structure were prepared by different loading sequences. Their particle size, morphology and thermal pyrolysis behavior were compared. The results showed that the particle distribution of three powders is uniform and the dispersity of them is good. The active components of explosion suppression are evenly loaded on the waste molecular sieve carrier and they have different coating structure. The thermal desorption heat of them is 44.64 J/ g, 66.95 J/g and 92.9 J/g, respectively. Furthermore, the flame propagation characteristics of coal dust were tested by the Hartmann flame propagation device. The results showed that all powders had the effect of inhibiting the flame propagation of coal dust and the inhibition effect is S@ T -K, S@T/K and S@K/T from strong to weak. Combined with characterization results, the influence mechanism of the difference in the flame propagation inhibition effect of three suppressants was investigated.

Coal Dust Characteristics and Its Association with Air Quality in Palembang Coal Unloading Station

The problem of coal dust due to the accumulation and loading of coal to barges for shipping has not been studied optimally. This study aimed to investigate the characteristics of coal dust and the air quality of the three coal industries. Coal dust characteristics were tested through proximate analysis, XRD, XRF, and SEM. Meanwhile, air quality is viewed from exposure to gases that cause emissions (CO, NO2, and SO2), PM10 and TSP, humidity, and temperature. Coal dust consists of SiO2, Al2O3, and Fe2O3 as the main components with high ash. Exposure to SO2 and TSP can potentially exceed the annual threshold value.

Research on the influence and suppression technology of micron foreign matter for gas insulated switchgear

Breaking–closing of the circuit breaker inevitably produces micron metal dust, significantly affecting the internal insulation state of the GIS. This paper first analyzes the force characteristics of micron metal dust and its separation characteristics inside the circuit breaker, then builds a test platform supporting 520 kV power frequency withstand voltage and 1175 kV lightning impulse withstand voltage based on true type 363 kV GIS to investigate the influence of micron foreign matter on the insulation performance of GIS. Subsequently, ANSOFT is used to simulate the electric field distortion when there is micron metal dust inside the circuit breaker, and the influence of foreign matter on the degree of electric field distortion under the action of the flow field. The characteristics of the influence of micron foreign matter on the insulation performance of foreign matter inside the GIS are summarized. Secondly, using artificial micron foreign matter, the pulse current and the UHF methods are adopted to detect the discharge amount. The sensitivity of different detection methods to the discharge detection of the micron foreign matter is analysed, plus the partial discharge characteristics of the micron foreign matter under different voltages. Afterwards, based on the test results of micron foreign matter, two improvement measures are proposed, including the treatment of foreign matter inside the GIS and the dual-light source angiography inspection, so as to reduce the influence of micron foreign matter on the insulation status of the GIS. Finally, through the AC withstand voltage test of artificial embedded foreign matter and the insulation margin check under 1.1 times lightning impact, the effectiveness of the measures proposed in this paper is verified, thus providing technical support for certifying the impact of micron foreign matter on the insulation state during equipment operation and maintenance.

Effects of fire extinguishing agents on pyrolysis and explosion characteristics of optical brightener dust

As a widely used optical additive, optical brightener has a potential risk of dust explosion during production and utilization, which limits its further application. In this paper, the pyrolysis process and explosion characteristics of universal optical brightener OBA-184 dust were studied, and the inhibition effects of NH4H2PO4, NaHCO3, and aerosil (nano-silica) were compared using the Hartmann tube and the 20-L spherical explosion system. The results illustrate that OBA-184 dust is a substance with huge heat of decomposition. All three extinguishing agents can effectively moderate the ignition sensitivity and explosion severity. Among them, NH4H2PO4 has the best efficiency in suppressing explosion severity due to its excellent chemical inhibition effect. The complete inert ratio of NH4H2PO4 was about 60% lower than that of NaHCO3, while aerosil can not completely inert the OBA-184 dust at the inert ratio in the range studied. NaHCO3 can significantly reduce the ignition sensitivity of OBA-184 dust, and adding 60% NaHCO3 can reduce the dust to a low sensitivity level. Inerting is accomplished due to its low decomposition temperature and violent heat absorption rate; Aerosil is less effective than NH4H2PO4 and NaHCO3, which attributes to its poor physical heat absorption and weak chemical inhibition ability. The results of this paper provide a theoretical and practical basis for dust explosion prevention and control in the optical brightener industry.

Effects of volatile organic compounds on the explosion characteristics of polyethylene dust

This study investigated the effects of different concentrations of ethylene and propene gas on the explosion characteristics of polyethylene (PE) dust. After the addition of ethylene and propene gases, the maximum explosion pressure of PE dust increased from 6.7 barg to 9.1 and 7.6 barg by 1.4 and 1.1 times, respectively. Furthermore, the lower explosion limit (LEL) decreased; the addition of even a small amount of these inflammable gases was sufficient to produce a hazardous gas/dust hybrid mixture with low LEL. PE dust tests in a 2 vol. % propene environment revealed that an initial explosion occurred in the hybrid gas mixture, and the heat was transferred to the remainder of the incompletely mixed gas/dust mixture, thereby leading to a two-stage and more complete reaction. In addition, 2 vol. % propene tests also exhibited changes in the maximum pressure rise rate increase, resulting in strong St-2 level explosions because the propene reached its LEL of 2 vol. %. Therefore, propene underwent a complete combustion, resulting in a higher rate of pressure, and shortened time to maximum rate of pressure rise (TMRPR). Thus, the use of volatile organic compounds in dust manufacturing processes considerably increases the risk of explosion incidents.

Study on Temporal and Spatial Distribution and Transport Characteristics of Dust in New Composite Spraying Slurry

In view of the problems of traditional spraying technology, such as complex processes, high costs, large dust amounts, and poor air leakage effects, a new composite spraying slurry is proposed in this paper, which takes clay as the main base material and uses water pressure and wind pressure to ensure intrinsic safety. Firstly, the airtightness, bending resistance, and viscosity of the spraying material were measured in the laboratory; secondly, the gas–liquid–solid three-phase flow process involved in the spraying process was simulated by using the CFD-DPM method, adopting the Eulerian two-fluid model for continuous gas–water two-phases and the discrete phase DPM model for dust generation, and the transport, diffusion, and full space-time distribution characteristics of dust generation were studied. The research shows that: (1) the new composite slurry spraying material made of clay as the main material is made by adding a small proportion of cement and engineering fiber to increase the toughness of the material, and finally, determining the mass ratio of the composite material as follows: clay: cement: additive: engineering fiber = 84:14:1.85:0.15. It has good sealing and bending resistance and good adhesion; (2) the water phase distribution under the action of spray determines the distribution of solid-phase dust, and the distribution area of dust is similar to that of the water phase; (3) under the action of spray, the area at the bottom of the roadway is covered by dust flow, and the dust in this area is obviously stratified. The particle size of the dust gradually decreases from bottom to top. The large particle size dust is deposited at the bottom, while the small particle size dust is suspended at a certain height, and the diffusion area gradually increases; (4) the effect of spray angle on dust is mainly manifested in the initial dust flow shape and dust diffusion time. The larger the spray angle, the faster the diffusion; (5) when the water velocity at the nozzle outlet is large, the dust concentration is low in the whole area, but in areas higher than 1.5 m, the PM2.5 concentration also increases with the increase in water flow. The dust suppression effect of larger a water flow is mainly reflected in the bottom area, and the disturbed surrounding airflow can make PM2.5 diffuse to higher areas.

Dust emission and transport in the Aral Sea region

The rapid drying of the Aral Sea has led to a series of complex environmental changes and a large amount of aeolian dust have been swept up from the exposed bottom. This study used a wind erosion model and the Hysplit model to investigate emission and transport characteristics of the Aral Sea dust. The spatial pattern of dust emission was determined by quantifying the surface conditions. The total source area in the Aral Sea region exceeds 27,000 km2, with annual average dust emission of up to 87.6 Tg from 2010 to 2020. The main source of dust was found to be in the eastern Aral Sea basin. The spatial pattern of dust emission in a year was seasonal and the highest value and the widest spatial range occurred in spring. Modeling of a dust event on March 22, 2020 showed that PM10 dust emitted from the Aral Sea region can be transported over 4,000 km, and the area of land surface affected was more than 6.21 × 106 km2. The potential impact area of the Aral Sea dust was mapped by the numerical simulations for the past 24 severe dust storms, which indicates that the Aral Sea dust can reach the Arctic Ocean, Iran, the Atlantic Ocean through France, and the Pacific Ocean through Japan, covering a land area of more than 38.5 × 106 km2.

Morphological Characteristics of Bamboo Panel Milling Dust Derived from Different Average Chip Thicknesses

The massive amounts of dust formed during bamboo CNC milling presents serious risks to human health and equipment. The present study aimed to determine the particle size distribution (PSD) and shape characteristics of bamboo milling dust derived from different average chip thicknesses. Spindle speed and feed rate were varied in combination, in setting up two experimental groups having the same average chip thicknesses. Sieving and flatbed scanning image analyses were collectively utilized for the morphological analysis of bamboo dust. The results showed that less than 5% of the particles were below 100 μm in terms of mass, but represented more than 83% in number. Average chip thickness was positively correlated with a mass proportion of bamboo dust with large size, which was preferably generated when reducing spindle speed instead of increasing feed rate. Spindle speed and feed rate individually affected the particle size and particle size distribution instead of average chip thickness. The aspect ratio, roundness and convexity of bamboo milling dust were augmented with a reduction in particle size, indicating that bamboo milling dust with smaller size had more a regular shape, a smoother profile and fewer corners. These findings provide a theoretical basis for better understanding bamboo milling dust and its related control in the bamboo processing industry.

Surface pore characteristics of original coal dust produced in underground mining sites and their impact on the moisture content

In underground coal mines, the efficiency of water-based dust suppression technologies is heavily limited by the poor wettability of coal dust. To explore the effect reasons of the surface pore parameters of coal dust on its wettability, in this study, 18 original coal dust (OCD) samples produced in underground mining sites were collected from various underground coal mines in north China. The surface micropore (pore size <2 nm) and mesopore (2 nm < pore size <50 nm) characteristics of the OCD samples were measured with the nitrogen (N2) adsorption/desorption method. Subsequently, the correlations between the pore characteristics of the OCD samples and their moisture contents and initial contact angle (ICA) were established and discussed. The results demonstrate that the pore structures of the OCD samples are significantly developed, and the impermeable pores with one open end are the dominant pore types in the OCD. The micropore structure of the OCD samples considerably affects its moisture content, thus influencing its wettability. As the increase of micropore size, micropore volume, and specific surface area (SSA), the moisture content of the OCD samples linearly decreased (R2 =0.55), linearly increased (R2 =0.66), and linearly increased (R2 =0.65), respectively. The large capillary force caused by the developed SSA accounts for the significant moisture conservation property of the micropore structures, which improves the wettability of the OCD. The variation of the ICA with the pore parameters well verifies this conclusion.

Study on Combustion Kinetic Characteristics of Lignite and Semi-coking Dust.

In order to master the combustion kinetic characteristics of semi-coking dust in the early pyrolysis stage of lignite combustion explosion, a vacuum tube furnace was used to prepare semi-coking dust with different pyrolysis degrees, and the experimental samples were studied by a synchronous differential thermal analyzer. By means of theoretical analysis, the reaction mechanism of lignite and semi-coking dust was revealed. The results show that when the final pyrolysis temperature rises to 920 °C, the percentage of volatile matter decreases by 94.6%. The reaction in this process also causes the original pores to be cross-linked and collapsed, and a large number of new pores are generated, and the original pore structure is significantly enlarged. With the increase of the final temperature of pyrolysis, the ignition temperature (Tb) of the dust increased from 354 to 455 °C, the fastest reaction temperature (Tc) increased from 399 to 495 °C, and the ember temperature (Td) increased from 558 to 658 °C. The maximum combustion rate decreased by 65.97%, and the average combustion rate decreased by 84.67%. The apparent activation energy increased by 4.7 times from 45.219 to 257.665 kJ/mol, and the combustion kinetics of semi-coke became worse. The thermal reaction of lignite and semi-coking dust conforms to the diffusion mechanism of the three-dimensional spherical symmetry model. The research results provide a new idea for discussing the mechanism of coal dust explosion and the development of explosion suppression technology.

Study on coal dust diffusion law and new pneumatic spiral spray dedusting technology at transfer point of mine cross roadway.

In order to solve the problem of coal dust pollution at the transfer point, a three-dimensional numerical model of wind flow-coal dust at the loading point of underground rubber run was established by computational fluid dynamics (CFD) discrete particle model and finite element method and k-ε turbulence model, and the coal dust diffusion pollution phenomenon caused by the coal flow transfer under the intersection of wind flow in the cross tunnel was studied. Based on the simulation results of wind flow velocity contour, pressure contour and isochronous flow vector distribution, the influence mechanism of wind flow and coal dust characteristics on the distribution of wind flow and coal dust diffusion in the roadway is analysed, and a dust control and reduction system and treatment scheme with new pneumatic screw spray technology as the core is proposed to suppress coal dust pollution at the reloading point. The results of the study show that the wind flow distribution is mainly influenced by the intersection of tape traction and cross-roadway wind flow, showing a complex multi-layer distribution along the roadway and in the normal direction; the diffusion of coal dust of different particle sizes is influenced by the roadway wind flow, and coal dust with particle sizes in the range of 10μm~20μm is more easily diffused, and the dust with particle sizes in the range of 20μm~45μm is mainly collected and suspended near the vortex wind flow at the cross-roadway. The coal dust in the range of 20 μm~45 μm is more likely to gather in the vortex; the treatment system effectively controls the coal dust inside the dust cover, and the spiral-shaped transported droplet particle group formed by the pneumatic spiral spray combines with it efficiently, which verifies the dust control and reduction effect of the pneumatic spiral spray system at the transfer point, and the dust removal efficiency reaches 89.35%~93.06%, which provides relevant theoretical support for the treatment of dust pollution at the coal transfer point in underground coal mines It provides the theoretical support and means to control dust pollution at underground coal transfer points.

Research on the Effect of Extinction Characteristics of Coal Dust on Visibility.

A good knowledge of the reduction mechanism of visibility is fundamental to developing preventive strategies in coal mines. In this work, the Mie theory was selected for investigating the absorption and scattering of coal dust. A prediction model for evaluating the visibility was developed based on the extinction characteristics of coal dust. The optical properties have been discussed to simplify the model and clarify the relationships among the different wavelengths and diameters. Additionally, the variety of extinction coefficients can be reasonably used in guiding the calculated visibility under different conditions. The experimental results demonstrated that the reduction of visibility was attributed to the synergistic effect of the extinction of coal dust and droplet. For the field application of this prediction model, the relative errors of the calculated and measured visibility were 9.8 and 7.1% from models I and II, which reflected the small deviation between the two methods. The prediction model can accurately describe the visibility in mines due to coal dust pollution. The exploration results provide a significant reference for the development and application of air cleaning technology for increased visibility.

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 Respirable Dust Generated from Full Scale Cutting Tests in Limestone with Conical Picks at Three Stages of Wear

Respirable rock dust poses serious long-term health complications to workers in environments where mechanical rock excavation is utilized. The purpose of this study is to characterize respirable dust generated by cutting limestone with new, partially worn, and fully worn conical pick wears. Characterizing limestone respirable dust can aid in decision making for respirable dust suppression levels and exposures throughout the lifetime of a pick in underground mining and engineering activities. The methods include full scale cutting of a limestone sample in the laboratory with three conical picks at different stages of wear. Dust samples were collected during cutting with various instruments connected to pumps and subsequently analyzed to determine the concentrations, mineralogy, particle shapes, and particle size distributions. The results show that the worn pick generated the highest concentration of dust, all picks generated dust containing quartz, all three picks generated dust particles of similar shapes, and all three picks generated various particle size distributions. In conclusion, a preliminary suite of respirable dust characteristics is available and with further future additional studies, results could be used for the evaluation of possible strategies and methods of dust suppression and exposures during mining, tunneling, or drilling activities.

Investigation of Quarry Fine Effects on Cement Plaster

The necessity to find alternatives to sand as fine aggregates in the production of plaster has increased due to the diminishing sources of natural sand and the requirement to reduce the cost of cement plaster. One of these components is quarry dust, a by-product of the crushing operation during quarrying activities. Granite fines, also known as rock dust or quarry dust, are a byproduct of crushing granite boulders. The goal of the current work is to replace sand with quarry dust and improve the mixture of cementitious materials and quarry fines. The basic characteristics of quarry dust and the compressive strength of quarry dust concrete have been attempted to be studied. The compressive strength of cast cement mortar cubes was estimated. For plastering, cement mortar in the ratios of 1:3, 1:4, 1:5, and 1:6 is created, and water absorption in the quarry fines is measured as a percentage. The workability of quarry dust is comparable to that of traditional fine aggregate (sand), and it contains nearly identical components to those found in EDAX. In the current work, the behaviour of cement mortar paste has been experimentally investigated. A range of cement mortar properties, including workability and compressive strength tests after 3 and 7 days of curing, have been the subject of experimental research.

Relationship Between Exposure Levels of Dust Polymethyl Methacrylate And Characteristics of Workers With Subjective Respiratory Complaints in Dental Engineering Laboratory, Dki Jakarta Region in 2021

The manufacture of dentures, especially from polymethyl methacrylate affects the health of workers, especially those related to breathing. The manufacture produces dust of various sizes. The effects of exposure to dust cause discomfort at work and have a negative impact on health. This research objective was to determine the relationship between exposure to polymethyl methacrylate and subjective respiratory complaints. The method used was analytical quantitative research with a cross-sectional with a sample of 5 objects and a sample of 30 workers.dust content polymethyl methacrylate with a Portable High Volume Air Sampler and measurement of subjective respiratory Complaints with a questionnaire. There is a relationship between exposure to dust levels of polymethyl methacrylate on subjective respiratory complaints with p value = 0.006. The dust content of polymethyl methacrylate exceeds the threshold value at 2 sites (40% of the samples). There is a relationship between exposure to dust levels of polymethyl methacrylate on subjective respiratory complaints, p value 0.006 (p &lt;0.05).

Characterization and Toxicity Analysis of Lab-Created Respirable Coal Mine Dust from the Appalachians and Rocky Mountains Regions

Coal mine workers are continuously exposed to respirable coal mine dust (RCMD) in workplaces, causing severe lung diseases. RCMD characteristics and their relations with dust toxicity need further research to understand the adverse exposure effects to RCMD. The geographic clustering of coal workers’ pneumoconiosis (CWP) suggests that RCMD in the Appalachian region may exhibit more toxicity than other geographic regions such as the Rocky Mountains. This study investigates the RCMD characteristics and toxicity based on geographic location. Dissolution experiments in simulated lung fluids (SLFs) and in vitro responses were conducted to determine the toxicity level of samples collected from five mines in the Rocky Mountains and Appalachian regions. Dust characteristics were investigated using Fourier-transform infrared spectroscopy, scanning electron microscopy, the BET method, total microwave digestion, X-ray diffraction, and X-ray photoelectron spectroscopy. Inductively coupled plasma mass spectrometry was conducted to determine the concentration of metals dissolved in the SLFs. Finer particle sizes and higher mineral and elemental contents were found in samples from the Appalachian regions. Si, Al, Fe, Cu, Sr, and Pb were found in dissolution experiments, but no trends were found indicating higher dissolutions in the Appalachian region. In vitro studies indicated a proinflammatory response in epithelial and macrophage cells, suggesting their possible participation in pneumoconiosis and lung diseases development.