Total Dust Concentration Research Articles

Study on dust pollution suppression of mine wind-assisted spray device based on orthogonal test and CFD simulation

To solve the problem of high-concentration coal dust pollution in a fully mechanized working face, and based on the principle of mechanical wind-assisted negative pressure suction of dust-laden air flow combined with spray dust reduction, a new wind-assisted spray device was investigated. The nozzle of the device was optimized through experimental investigation of the macroscopic characteristics of the spray field. Based on the actual situation of the fully mechanized mining face, a numerical simulation of the wind-assisted spray device was carried out and combined with an orthogonal test. It was shown that when the spray device deviates by 30°, the spray pressure is 6 MPa, and the air output is 90 l/min, resulting in a more efficient spray field. Finally, the wind-assisted spray device was used in the 22,104 fully-mechanized mining face of Shangwan Coal Mine, China, and the dust concentration was monitored at measuring points before and after the spraying device was switched on. The concentration of total dust and respirable dust at the shearer driver's position decreased to 104.2 mg/m³ and 68.3 mg/m³, respectively, and the dust removal efficiency reached 88.31% and 83.45%, respectively, which effectively suppressed the high-concentration coal dust pollution in the working face.

Particulate Matter Concentration in Selected Facilities as an Indicator of Exposure to Their Service Activities.

In recent years, the correlation between the concentration of pollutants in the atmosphere and inside buildings has been reported as high. The air inside living quarters and public utility buildings or the interiors of public transport vehicles, as well as the relationship between the internal and external sources of particulate matter (PM) and gaseous pollutants, have underwent sufficient research. On the other hand, non-production rooms, i.e., offices, restaurants, beauty salons, etc. remain very poorly recognized in this respect. For the above reasons, the aim of this work is to determine the difference in the total dust (TSP) and respirable PM (PM4) concentrations in selected rooms, i.e., offices and beauty centers, in relation to their outdoor concentrations. They were measured at six locations in accordance with the standard for the conditions at workplaces by means of PM aspirators. Indoor concentrations of TSP and PM4 were much higher than those in the external surroundings of the facilities. There were no significant relationships between the TSP and PM4 concentrations inside and outside tested rooms. Although the characteristic of the internal PM essentially depends on the characteristics of the external PM migrating to the interior of the premises, considering some types of non-production premises, internal emissions fundamentally changed the characteristics of PM.

Occupational Dust Exposure and Respiratory Protection of Migrant Interior Construction Workers in Two Chinese Cities.

Migrant interior construction workers are increasing in China. Construction workers are at an increased risk of work-related illness (WRI) due to prolonged exposure to and inhalation of dust. Dust concentrations in the air can be reduced significantly with effective respiratory protection measures. We assessed the dust exposure and factors associated with respiratory protection of migrant interior construction workers. The total dust concentration in the workplace ranged from 0.07 to 335.27 mg/m3, with a total dust exceedance rate of 50.00%. The respiratory dust loading ranged from 0.03 to 220.27 mg/m3, with a respiratory dust exceedance rate of 71.42 %. The highest total dust concentration occurred when masons were polishing cement walls. We performed a questionnaire survey of 296 persons in two cities in China, in which 87.84% had no respiratory protection or only one protection measure. Gender, workplace, respiratory disease, and protective attitude all had an effect on the level of respiratory protection. The dust exposure in most jobs exceeds hygiene standards. The respiratory protection of migrant interior construction workers in China is inadequate.

Effect of the Surface Treatment Process of Filter Bags on the Performance of Hybrid Electrostatic Precipitators and Bag Filters

Hybrid electrostatic precipitators consisting of electrostatic precipitation (ESP) and a bag filter are potential devices for ultralow emissions. The ESP captures and charges the particles; subsequently, the charged particles that escape enter the bag filter. The charged particles can cause the electric field of the filter bag to develop, thereby enhancing the filtration efficiency due to the force of the electric field. Experiments based on the coupling-reinforced electrostatic–fabric integrated precipitator system were conducted to investigate the outlet total dust concentration, dust removal efficiency, pressure drop, energy consumption of bag filter, and hybrid electrostatic precipitators with various filter bags. The measured results demonstrate that the removal performance of filter bags with smaller fiber diameters was superior. However, the pressure drop and energy consumption were high due to the increased filtration resistance. Compared to bag filters, hybrid electrostatic precipitators had lower total and grade dust mass concentrations at the outlet, higher total and grade dust removal efficiencies, a minor average pressure drop variation per minute, and lower total energy consumption. Consequently, the quality factor was utilized to comprehensively evaluate the overall performance of dust collectors. The hybrid electrostatic precipitators had a significant greater quality factor; their overall performance was superior to that of bag filters. Overall, a smaller filter bag’s fiber diameter resulted in more effective dust removal capabilities. Hybrid electrostatic precipitators with various filter bags were significantly better than bag filters in terms of dust removal performance, cycle life, and energy consumption.

Dust pollution hazard and harmful airborne dust exposure assessment for remote LHD operator in underground lead-zinc ore mine open stope.

Underground mines embroil several occupational hazards, including airborne dust generation from various mining operations. Line-of-sight remote Load Haul Dumper (LHD) mucking is adopted to draw the blasted muck from unsupported open stopes in underground metalliferous mines. Assessment of particulate matter (PM) concentrations and remote LHD operator's exposure is crucial for devising appropriate dust control measures. In this study, PM generated due to mucking in longhole open stope by line-of-sight remote LHD during downcast airflow was measured using real-time aerosol spectrometers. The particulate concentrations at upstream and downstream of dust source were analysed for various particle sizes as well as occupational dust types, such as alveolic and thoracic. The airborne dust concentration of ≤ 10μm (PM10), ≤ 5μm, and ≤ 1μm (PM1) size at operator's location in downstream was measured 71.3%, 28.5%, and 3.0%, respectively. The alveolic and thoracic dust types, respectively, were determined 25.1% and 74.2% in downstream and 48.9% and 84.6% in upstream total airborne dust concentration (311 ± 246μg/m3). Dilution of airborne dust generated due to muck sliding inside the stope was analysed with time. Moreover, dust concentrations under typical airflow scenarios encountered in open stope were simulated using Ventsim software to identify the potential dust exposure hazard for remote LHD operator. The simulation revealed that downcast airflow causes maximum exposure of harmful airborne dust for remote LHD operator. This study enhanced the understanding of exposure potential of airborne dust during remote LHD mucking. Moreover, it emphasised adoption of tele-remote-operated LHD and automated mucking operation in open stopes.

Research on dust suppression technology of fully mechanized mining workers by section control of airflow

Taking the 20106 fully mechanized mining face of Wangjialing coal mine as the engineering background, this paper analyzes the action relationship between the dusty air flow and fresh air flow formed by the coal caving and dust production of the fully mechanized mining machine, and through the establishment of mathematical model and field test, the best matching parameters of the relative position between the axial and radial air outlet of the segmented air control and dust control system and the head-on of the working face are obtained. The field application shows that after the optimization of the parameters of the wind and dust control system, the dust reduction efficiency of the total dust concentration at the driver’s position and each transfer point can be increased by about 80%, and the dust reduction efficiency at the driver’s position can reach 91.8%. The high concentration dust is controlled within 2m in front of the work, which can prevent the escape and diffusion of dust to the rear, and the working environment is significantly improved.

Green Multiplex Chromatographic Determination of Nine Penicillin Antibiotics Residues in Industrial Air Dust and Wastewater Environmental Samples.

Determination of penicillin residues in different industrial effluents including wastewater and air samples is important to prevent exposure to residual amounts of penicillin and the development of antibiotic resistance. A green high performance liquid chromatography (HPLC) method coupled with diode array detection has been developed and validated for multiplex determination of nine penicillin antibiotics in the industrial air dust and wastewater environmental samples of penicillin facility in addition to the monitoring of facility surface cleaning. Separation was performed on C18 column with gradient elution of methanol and phosphate buffer (pH 4) at a flow rate of 1.5 mL min-1 and ultra violet (UV) detection at 220nm. Low limits of detection were achieved (0.1-0.3 μg mL-1) indicating good sensitivity of the proposed. The method was applied for ensuring the efficiency of cleaning validation after worst-case selection. Recovery studies of the studied penicillins from fortified stainless steel and polycarbonate surfaces and swabs were between 91.91 and 100.22% with relative standard deviation 0.11-1.79%. The presence of any of the studied penicillins in wastewater samples from penicillin plant drainage was checked. Also, total air dust concentration (mg m-3) and % of penicillin active material residues in air dust were calculated from the area of the exposed group in suspension, tablet and vial production lines. The proposed method can be recommended for routine analysis of air and wastewater environmental samples for the detection of penicillin antibiotics at low levels as well as monitoring of facility surface cleaning with high accuracy and precision.

Mixed-dust pneumoconiosis in a dental technician: a multidisciplinary diagnosis case report

BackgroundIn dental laboratories, exposure to crystalline silica can occur during procedures that generate suspended mineral dusts, e.g. dispersion of mixing powders, removal of castings from molds grinding, polishing of castings and porcelain, and use of silica sand for blasting. There is also a large list of toxic agents (acrylic resins, polymeric materials, etc.) used to produce removable and fixed prostheses, but also impression materials and more. Using personal protective equipment and other aids reduces the exposure to these potentially harmful agents.Case presentationWe report the case of a 42-year-old male dental technician who began to suffer from a dry cough and exertional dyspnea after approximately 15 years of work. The operations he conducted for his job resulted in the generation of crystalline silica, aluminum, chromium and titanium dust. The worker did not regularly wear personal protective equipment and some of the above operations were not carried out in closed circuit systems. The Chest X-ray showed diffused micronodules in the pulmonary interstitium of the upper-middle lobes, bilaterally, and a modest left basal pleural effusion. Simple spirometry showed small airway obstruction in its initial stage. High Resolution Computerized Tomography of the chest showed bilateral micronodulation of a miliariform type, with greater profusion to the upper lobes, also present in the visceral pleura, bilaterally. Histological examination showed aggregates of pigment-laden macrophages forming perivascular macules or arranged in a radial pattern around a core of sclerohyalinosis. Scanning Electron Microscopy and Energy Dispersive Spectrometry revealed several mineral particles, typically characterized by the presence of crystalline silica and metal aggregates. The environmental concentrations of total dust and its respirable fraction were all lower than the relative TLV-TWA—ACGIH, yet not negligible.ConclusionsThe above findings and a multidisciplinary assessment led to the diagnosis of mixed dust pneumoconiosis s/q with 2/2 profusion of occupational origin. This diagnosis in a dental technician was supported for the first time in literature by environmental exposure analysis.

Respiratory symptoms and dust exposure among cement processing factory workers,Tanzania

Background: Cement manufacturing is among the growing industry in Tanzania. It involves processes from blending, kiln burning, clinker, grinding and cement final production. All of these cement manufacturing processes generates cement dust which contain silica and other toxic materials which can potentially affect respiratory system of exposed workers. Methods: This cross sectional comparative study design was conducted at cement processing factory and Ndanda mineral water processing factory as control, all of these factories are located in Mtwara region in Tanzania. A total of 398 workers were selected randomly from these two factories. Data were collected using structured questionnaires for respiratory health symptoms, Checklists was used for the observational parameters. Dust sampling was done using Side Kick Casella (SKC) pumps and PVC filter on IOM cassettes was used to determine dust exposures. The analysis was done by SPSS program vers 20. The significant association between the dependent variable and the factors was registered when Pvalue was less the 0.05. Results: Packing and cleaner were the sections with higher total cement dust concentrations above Occupational Exposure Limit which were 33.24 and 15.39 mg/m3 respectively. Workers in cement processing factory were exposed to higher levels of total dust with AM 14.1033 mg/m3 (SD 4.357) than in mineral water processing factory AM 0.0867 mg/m3 (SD 0.035). The Prevalence of respiratory symptoms was higher among workers in cement processing factory (45.7%) than in mineral water processing factory (25%), this was statistically significant. Conclusion: Exposure to cement dust in a working environment causes the increase in work related respiratory symptoms and reduced lung function. A control measure to decrease the dust exposure level among cement workers in line with periodic medical examination is highly needed.

Trace elements and nutrients in wildfire plumes to the southeast of Australia

The unprecedented magnitude of the 2019–20 Australian fires have raised interest in the potential for fire emissions to supply vital nutrients to remote ocean regions. Fire emissions are episodic and unpredictable, making them difficult to investigate. Here we present results from continuous monitoring of the atmospheric composition at the kunanyi/Mount Wellington time-series station, in southeastern Tasmania (Australia) between 2016 and 2020. Characterization of aerosols at the station revealed a striking increase in the atmospheric loading of iron (Fe), nitrate (NO3−), ammonium (NH4+) and manganese (Mn) associated with fire events. High concentrations of mineral dust in fire-impacted aerosols evidenced that strong pyro-convective winds resulted in the erosion and entrainment of soil particles into the atmosphere alongside the fire plume. Enrichment factor (EF) analysis in aerosols suggested that soil dominated the atmospheric loading of Fe and Mn in fire emissions. Lead (Pb) enrichment in fire aerosols (EFPb > 10) was attributed to the resuspension of soil historically contaminated by leaded petrol and mining operations. Finally, atmospheric transport was showed to play a key role in decreasing concentrations of total Fe (TFe) and mineral dust while increasing the aeolian content of bioaccessible Fe (LFe), NO3− and NH4+ in the plume downwind of the fires. As future projections suggest an increase in fire activity worldwide, atmospheric time-series stations such as kunanyi/Mount Wellington are key to better understand future impacts of fire emissions on human health and natural ecosystems.

Assessment of explosion risk for wood dust in a ventilation-dust separation installation, by determining the concentration of total dust in suspension inside of the installation

Most of combustible dusts present both fire and explosion hazard. Explosion may occur at certain concentrations of dust mixed with air and in the presence of an ignition source. The threat posed by this real danger was confirmed by the events that took place in economic units such as: feed factories, wood products, textile industry, steel, etc. Among the parameters of explosiveness of combustible dust, which can cause an explosion, we mention: maximum explosion pressure, lower explosion limit, explosive index, minimum ignition energy, electrical resistivity of dust, minimum ignition temperature of dust layer and cloud, particle size and concentration of dust in suspension. The current paper presents the results of determinations of combustible wood dust concentrations, performed at an important economic unit, manufacturing veneer and wood panels, at a dusting ventilation installation composed of fan, cyclone and textile filter. These determinations were made in the pipe connecting the fan and the bag filter, to assess possible danger of explosion in the pipe, by relating the measured concentration to the lower explosion limit (concentration of wood dust).

Quantifying Farmers’ Exposure to Corn and Soybean Dust in On-Farm Grain Storage Bins

HighlightsOn-farm samples were used to analyze farmers’ exposure to dust while cleaning and unloading their grain bins.Over 18% of samples exceeded the 8-hour time-weighted average (TWA) concentration recommended by ACGIH for respirable dust, and over 27% of samples exceeded the ACGIH recommendation for total suspended particles.The results strengthen the need for relevant agricultural safety education programs to help farm workers understand the health hazards associated with grain dust.Abstract. Grain dust consists of grain particles, insect parts, silica, bacteria, fungi, and mycotoxins. The size of these airborne particulates is a concern because they can become deeply lodged in the respiratory tract. Exposure to grain dust can diminish overall lung function and lead to respiratory diseases such as asthma, chronic obstructive pulmonary disease (COPD), organic dust toxic syndrome (ODTS), chronic bronchitis, and hypersensitivity pneumonitis (farmer’s lung). Grain storage and handling facilities are primary work locations with high levels of grain dust concentrations. The objective of this study was to understand farmers’ exposure to grain dust while cleaning and unloading their grain bins. During on-farm dust sampling, researchers visited farms to collect dust samples for analysis. Two types of samples were taken. Integrated samples provided average concentrations of total dust and respirable dust while farmers performed their normal tasks in the grain bin. Real-time samples provided instantaneous concentrations of respirable dust (RESP) and total suspended particles (TSP) and how the variations changed during the farmers’ working periods. From the data collected in corn storage bins, RESP concentrations ranged from 4.1 to 6.6 mg m-3, and TSP concentrations ranged from 33 to 70.7 mg m-3. From the data collected in soybean storage bins, RESP concentrations ranged from 1.6 to 82.3 mg m-3, and TSP concentrations ranged from 8.9 to 146.8 mg m-3. Based on the calculated 8-hour time-weighted average (TWA) concentration of all samples, 18.2% of the 8-hour TWA RESP concentrations exceeded the ACGIH-recommended respirable dust concentration of 3 mg m-3, and 27.3% of the 8-hour TWA TSP concentrations exceeded the ACGIH-recommended total dust concentration of 610 mg m-3. The results strengthen the need for relevant agricultural safety education programs to help farm workers understand the health hazards associated with grain dust. Keywords: Grain dust concentrations, Occupational health, On-farm grain storage bins.

Microbiological and toxicological hazard assessment in a waste sorting plant and proper respiratory protection

Even though biological hazards in the work environments related to waste management were the subject of many scientific works, the knowledge of the topic is not extensive. This study aimed to conduct a comprehensive assessment of microbiological and toxicological hazards at the workstations in a waste sorting plant and develop guidelines for selecting filtering respiratory protective devices that would consider specific workplace conditions. The research included the assessment of quantity (culture method), diversity (high-throughput sequencing), and metabolites (endotoxin - gas chromatography-mass spectrometry; secondary metabolites - liquid chromatography tandem-mass spectrometry) of microorganisms occurring in the air and settled dust. Moreover, cytotoxicity of settled dust against a human epithelial lung cell line was determined with an MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. The research was performed in a waste sorting plant (Poland; 240,000 tons waste/year) at six workstations: two feeders, two pre-sorting cabins, secondary raw material press and organic fraction waste feeder for composting.The total dust concentration at tested workstations varied from 0.128 mg m−3 to 5.443 mg m−3. The number of microorganisms was between 9.23 × 104 CFU m−3 and 1.38 × 105 CFU m−3 for bacteria and between 1.43 × 105 CFU m−3 and 1.65 × 105 CFU m−3 for fungi, which suggests high microbial contamination of the sorting facility. The numbers of microorganisms in the air correlated very strongly (R2 from 0.70 to 0.94) with those observed in settled dust. Microorganisms representing Group 2 biological agents (acc. to Directive, 2000/54/EC), including Corynebacterium spp., Pseudomonas aeruginosa, Staphylococcus aureus, and others potentially hazardous to human health, were identified. The endotoxins concentration in settled dust ranged from 0.013 nmol LPS mg−1 to 0.048 nmol LPS mg−1. Seventeen (air) and 91 (settled dust) secondary metabolites characteristic, e.g., for moulds, bacteria, lichens, and plants were identified. All dust samples were cytotoxic (IC50 values of 8.66 and 56.15 mg ml−1 after 72 h). A flowchart of respiratory protective devices selection for biological hazards at the workstations in the waste sorting plant was proposed based on the completed tests to help determine the right type and use duration of the equipment.

Optimization of spraying dust reduction technology of continuous miner machine and the dust environment in a tunnel, based on computational fluid dynamics (CFD) technology

We aimed to solve the problem of excessive dust concentration during the tunneling process of continuous mining. According to the analysis, the optimal nozzle was an X-type 2.0-mm nozzle, and the optimal layout was eight nozzles on the upper side of the cutting arm of a continuous miner machine, along with three nozzles on the left side, three nozzles on the right side, and four nozzles on the lower side. The spraying pressure was 6 MPa, and the spray flow rate was 2.484 L/s. The field application was carried out in the continuous mining tunnel of Jinjitan Coal Mine, China. During the field application, the total dust concentration was reduced to 16.9 mg/m3, the respirable dust concentration was reduced to 5.3 mg/m3, and the dust reduction rate was more than 89.2%. As a result, the problem of dust pollution in the continuous mining tunnel was effectively solved.

Characteristics of Agricultural Dust Emissions from Harvesting Operations: Case Study of a Whole-Feed Peanut Combine

The rapid development of peanut mechanization has increased the amount of dust expelled from peanut mechanized operations, which degrades the air quality and endangers the health of agricultural workers. Therefore, the purpose of this study is to figure out the characteristics of dust emission from mechanized peanut harvesting. To this end, the particulate matters of diameters ≤ 2.5 μm and ≤10 μm and the total suspended particles were sampled in real time during peanut harvesting in Henan Province, China, and the airborne particle concentrations and particle size distributions were measured. The dust particles discharged during the mechanized peanut harvesting were concentrated within the 2~30 µm size range. When the wind speed was reduced below the settling velocity of the largest particles, the more massive particles were carried in the downwind. The amount of free silica in the dust samples was determined by X-ray diffraction analysis. Both the total dust and free silica concentrations exceeded the occupational exposure and threshold limits. To improve the characteristics of dust emission, the microstructure and dispersion of the dust were also investigated. Reducing the agricultural operations during periods of high wind speed, low crop-moisture content, and low air humidity is recommended for reducing the dust exposure of workers. The results will provide guidance and technical support for reducing the dust emissions of mechanized harvesting operations, improving air quality, and reducing the health hazards to operators.

Microbiological and Toxicological Hazards in Sewage Treatment Plant Bioaerosol and Dust.

Despite the awareness that work in the sewage treatment plant is associated with biological hazards, they have not been fully recognised so far. The research aims to comprehensively evaluate microbiological and toxicological hazards in the air and settled dust in workstations in a sewage treatment plant. The number of microorganisms in the air and settled dust was determined using the culture method and the diversity was evaluated using high-throughput sequencing. Endotoxin concentration was assessed with GC-MS (gas chromatography-mass spectrometry) while secondary metabolites with LC-MS/MS (liquid chromatography coupled to tandem mass spectrometry). Moreover, cytotoxicity of settled dust against a human lung epithelial lung cell line was determined with the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay and UHPLC-Q-ToF-UHRMS (ultra-high-performance liquid chromatography-quadrupole time-of-flight ultrahigh-resolution mass spectrometry) analysis was performed to determine the source of cytotoxicity. The total dust concentration in the sewage treatment plant was low and ranged from 0.030 mg m−3 to 0.044 mg m−3. The highest microbiological contamination was observed in sludge thickening building and screenings storage. Three secondary metabolites were detected in the air and sixteen in the settled dust. They were dominated by compounds typical of lichen and plants and Aspergillus, Penicillium and Fusarium genera mould. The settled dust from the sludge thickening building revealed high cytotoxicity to human lung epithelial cells A-549 (IC50 = 6.98 after 72 h). This effect can be attributed to a biocidal compound—didecyldimethylammonium chloride (DDAC-C10) and seven toxic compounds: 4-hydroxynonenal, carbofuran, cerulenin, diethylphosphate, fenpropimorph, naphthalene and onchidal. The presence of DDAC-C10 and other biocidal substances in the sewage treatment plant environment may bring negative results for biological sewage treatment and the natural environment in the future and contribute to microorganisms’ increasing antibiotics resistance. Therefore, the concentration of antibiotics, pesticides and disinfectants in sewage treatment plant workstations should be monitored.

Experimental investigation on filtration characteristic with different filter material of bag dust collector for dust removal

ABSTRACT In order to solve the problems of insufficient filtration performance of bag dust collector in coal mine and improper selection of filter materials, the performance parameters of seven kinds of filter materials were compared and analyzed. The results showed that with the increase of filtration time, the resistance of different filter materials showed an upward trend, the resistance of ordinary filter material increased rapidly, while the resistance of membrane filter material increased more gently. The time required for ordinary filter material to reach the cleaning cycle is relatively short, the cleaning cycle of polyester filter material is 80s, and the amount of dust accumulated on the surface of membrane filter material is always in a rising state. When the dust particle size is between 6.5 μm and 23 μm, the dust removal efficiency of PTFE filter material increases with the increase of filtering wind speed; The field practice shows that after the LFD-45 horizontal film-coated flat bag precipitator with pre-installed PTFE filter material is installed on the tail guide trough of 106belt conveyor, the dust reduction rates of total dust concentration and respirable dust concentration are 98.57% and 98.95% respectively.

Exposure Assessment at a Pullet Barn - A Case Study

ABSTRACT Poultry production is an integral part of agriculture and of the U.S. economy, accounting for millions of eggs and chicken products consumed annually. Most ubiquitous to the poultry industry from farm production to research are broiler and layer poultry operations, with pullet operations at the forefront. Although essential to the cycles of production, there is a dearth of evidence regarding the occupational exposure risks of pullet production. The aim of this case study was to measure total dust and ammonia levels during the growth cycle of pullets. Ammonia and total dust concentrations were measured as single day measurements at three different points of time during the 16.5-week growth cycle of pullet flocks using two fixed sampling stations configured to represent the breathing zone height of poultry workers. As birds grew from chicks to hens, concentrations of total dust and ammonia increased. Notably, from 3 weeks-of-age to 9 weeks-of-age concentrations of total dust increased from 1.1–1.2 mg/m3 to 16.0–18.0 mg/m3; and from 9 weeks-of-age to 15 weeks-of-age, dust concentrations reached 43.0–50.0 mg/m3. Concentrations of ammonia also increased from 9 weeks to 15 weeks from 1.1–2.7 ppm to 22.0–30.0 ppm. Both levels of ammonia and total dust reached levels that have the potential to induce adverse health effects among farmers raising pullets.

A novel method for cleaning coal-dust-laden air and its application

During the green mining processes of coal energy, large amounts of coal-dust-laden air may be generated. This has caused serious health threats to mine workers. In this paper, a novel method for efficiently cleaning coal-dust-laden air was proposed. The method involved the use of air scrubbers composed of water inlet pipes, radial mixing impellers, water distribution plates, swirl vanes, and dehydrator. The radial mixing impellers were utilized to break up the water which flowed from the water inlet pipes to water distribution plates. As a result, water mist was formed, which then combined with the coal-dust-laden air, effectively sucking it using the negative pressure from the impeller rotation actions. The coal-dust-laden air and solid-liquid mixtures were moved along a certain trajectory by centrifugal force and gravity, and then discharged to the exterior. Experiments and field application processes were carried out in order to test the effectiveness of the proposed method. The experimental results showed that the dust removal efficiency of the method had reached 97.70 %. In addition, the proposed method was applied to a coal preparation plant in China’s Shanxi Province. The test results indicated that the average concentrations of total dust and respirable dust were found to have decreased from 71.11 to 2.89 mg/m3 and from 47.675 to 1.958 mg/m3, which met the requirements of environmental standards. Therefore, since the proposed method had not used conventional nozzles and filters, and had no requirements regarding the water quality of the coal mine, it had displayed strong adaptability and stable dust removal efficiency. The results obtained in this study showed that this new method of cleaning coal-dust-laden air was a promising measure by which to significantly improve the working environments of coal mines.

Inflammatory and coagulatory markers and exposure to different size fractions of particle mass, number and surface area air concentrations in the Swedish hard metal industry, in particular to cobalt

Purpose To study the relationship between inhalation of airborne particles and cobalt in the Swedish hard metal industry and markers of inflammation and coagulation in blood. Methods Personal sampling of inhalable cobalt and dust were performed for subjects in two Swedish hard metal plants. Stationary measurements were used to study concentrations of inhalable, respirable, and total dust and cobalt, PM10 and PM2.5, the particle surface area and the particle number concentrations. The inflammatory markers CC16, TNF, IL-6, IL-8, IL-10, SAA and CRP, and the coagulatory markers FVIII, vWF, fibrinogen, PAI-1 and D-dimer were measured. A complete sampling was performed on the second or third day of a working week following a work-free weekend, and additional sampling was taken on the fourth or fifth day. The mixed model analysis was used, including covariates. Results The average air concentrations of inhalable dust and cobalt were 0.11 mg/m3 and 0.003 mg/m3, respectively. For some mass-based exposure measures of cobalt and total dust, statistically significant increased levels of FVIII, vWF and CC16 were found. Conclusions The observed relationships between particle exposure and coagulatory biomarkers may indicate an increased risk of cardiovascular disease.