Diesel Particulate Matter Concentrations Research Articles

Characterization of trace elements of size-resolved particulate matter, development of emission factors and human health impacts associated with stationary diesel engine exhausts

The mass concentration of diesel particulate matter (DPM) and its elemental constituents (twenty-four) emitted from stationary diesel engine exhaust at ten different sizes (56 nm to 18 µm) increased with rise in engine-operating load. The maximum value of DPM concentration varied from 10.3 ± 2.4 mg/Nm3 at 0 % load to 20.4 ± 6.5 mg/Nm3 at 100 % load at size-bin of 0.10–0.18 μm. The elements of S, Ca, K, Al, Na, Mg, Fe, and Zn contributed as the major components to DPM mass with more than 90 % to total elements at six engine-operating loads. Ca, K, Al, Na, and Mg also showed higher values of EFs compared to Fe, Zn, As, Cr and Ni. Compared to Cu, Mn, Co, Se, Pb, Ba, Sr, fuel-based emission factor (EF) of Ti, Ga, Cd, Bi, and Te showed lower side of the estimated values. The levels of hazardous particulate elements generated from stationary diesel engine exhausts was a matter of concern from human health point of view as these elements showed better potential in causing significant cancer and non-cancer diseases through long-term exposure. The elements in DPM revealed significant deposition in the pulmonary and alveolar region of the human respiratory tract.

Applicability of aethalometers for monitoring diesel particulate matter concentrations and exposure in underground mines

Occupational exposure to diesel exhaust is regulated by legislation in Europe owing to its carcinogenic effects on humans. In underground mines, exposure to diesel exhaust requires regular monitoring. In this work, we investigate the usage of aethalometer AE33 and portable micro-aethalometer MA200 to assess occupational exposure to diesel exhaust in two underground mines. These instruments provide continuous data on wavelength-dependent particle light absorption, and based on this, equivalent black carbon (eBC) particle concentrations and potential sources. Both aethalometers correlated well with the thermal-optical elemental carbon analysis. Time-resolved aethalometer data revealed work-activity-dependent eBC concentration patterns that can be beneficial for identifying work phases that are significant for occupational exposure. In particular, high eBC peak exposures were observed for workers near load haul dumping areas. The diesel soot mass absorption cross-sections determined were similar for both mines. The absorption Ångström exponent determined from the aethalometer data was suitable for detecting and assessing the contributions of other potential sources to eBC concentrations, such as tobacco smoke, which is often prevalent in work environments. Overall, the portable micro-aethalometers proved to be suitable for monitoring occupational diesel exhaust exposure and can be useful for designing targeted exposure prevention measures in mining environments.

Sensitivity analysis and prediction of diesel particulate matter emissions in Indian underground metalliferous mines using regression and machine learning algorithms

Understanding the accumulation and dispersion characteristics of diesel particulate matter (DPM) in the closed environment of the underground mines and identifying the factors affecting these concentrations enables the mining authorities to formulate effective mitigation techniques to provide a safe and healthy working environment for the miners. For achieving this, DPM concentrations of three Indian underground mines were studied with a focus on the prediction of DPM using regression and Machine Learning (ML) algorithms and comparing their prediction accuracy. Multivariate regression analysis (MVRA) and Artificial neural networks (ANN) were utilised to correlate DPM concentrations and site-specific factors including the distance from the exhaust, ventilating air velocity, and source emission concentration. The results indicate that the best correlations between DPM concentrations and site parameters could be established by ANN with an R2 value of 0.986, while MVRA exhibited an R2 value of 0.916. Additionally, DPM concentrations were found to be most sensitive to gallery air velocity with a sensitivity index of (-) 2.87. The critical wind velocity above which the DPM concentrations reached below the safe permissible limits was determined to be 1.65 m/s for given cross-sectional profiles.

Spatial associations of long-term exposure to diesel particulate matter with seasonal and annual mortality due to COVID-19 in the contiguous United States

BackgroundPeople with certain underlying respiratory and cardiovascular conditions might be at an increased risk for severe illness from COVID-19. Diesel Particulate Matter (DPM) exposure may affect the pulmonary and cardiovascular systems. The study aims to assess if DPM was spatially associated with COVID-19 mortality rates across three waves of the disease and throughout 2020.MethodsWe tested an ordinary least squares (OLS) model, then two global models, a spatial lag model (SLM) and a spatial error model (SEM) designed to explore spatial dependence, and a geographically weighted regression (GWR) model designed to explore local associations between COVID-19 mortality rates and DPM exposure, using data from the 2018 AirToxScreen database.ResultsThe GWR model found that associations between COVID-19 mortality rate and DPM concentrations may increase up to 77 deaths per 100,000 people in some US counties for every interquartile range (0.21 μg/m3) increase in DPM concentration. Significant positive associations between mortality rate and DPM were observed in New York, New Jersey, eastern Pennsylvania, and western Connecticut for the wave from January to May, and in southern Florida and southern Texas for June to September. The period from October to December exhibited a negative association in most parts of the US, which seems to have influenced the year-long relationship due to the large number of deaths during that wave of the disease.ConclusionsOur models provided a picture in which long-term DPM exposure may have influenced COVID-19 mortality during the early stages of the disease. That influence appears to have waned over time as transmission patterns evolved.

Pollution and occupational protection of diesel particulate matter in underground space.

To address the diesel particulate matter pollution problem at the 12,306 continuous mining face of Shangwan coal mine, the spatial and temporal evolution law of diesel particulate matter generated at the three locations of the shuttle car head tunnel, contact alley, and support tunnel under the pressure-in ventilation condition of the double lane of the continuous mining face was studied by numerical simulation. The results show that the highest diesel particulate matter concentration at the shuttle car discharge is about 144.17mg/m3, which seriously affects the health of miners. The highest diesel particulate matter concentration at the shuttle car tunnel is 52.58mg/m3, and at the contact alley, the diesel particulate matter diffusion space is limited by the compression of the space inside the contact alley by the shuttle car machine body and the alley wall, which makes the diesel particulate matter accumulate here, forming a high diesel particulate matter concentration distribution area with a concentration value of 112.75mg/m3. When supporting the roadway at the shuttle, diesel particulate matter accumulates in the range of X = 55m ~ 60m, Y = 0m ~ 4m, and Z = 23.4m ~ 29.4m. According to the degree of DPM pollution in different areas, different individual protective equipment is used to obtain different levels of pollution protection.

Human Pluripotent Stem Cell-Derived Alveolar Epithelial Cells as a Tool to Assess Cytotoxicity of Particulate Matter and Cigarette Smoke Extract

Human pluripotent stem cells (hPSCs) can give rise to a vast array of differentiated derivatives, which have gained great attention in the field of in vitro toxicity evaluation. We have previously demonstrated that hPSC-derived alveolar epithelial cells (AECs) are phenotypically and functionally similar to primary AECs and could be more biologically relevant alternatives for assessing the potential toxic materials including in fine dust and cigarette smoking. Therefore, in this study, we employed hPSC-AECs to evaluate their responses to exposure of various concentrations of diesel particulate matter (dPM), cigarette smoke extract (CSE) and nicotine for 48 hrs in terms of cell death, inflammation, and oxidative stress. We found that all of these toxic materials significantly upregulated the transcription of pro-inflammatory cytokines such as IL-1α, IL-β, IL-6, and TNF-α. Furthermore, the exposure of dPM (100 μg/mL) strongly induced upregulation of genes related with cell death, inflammation, and oxidative stress compared with other concentrations of CSE and nicotine. These results suggest that hPSC-AECs could be a robust in vitro platform to evaluate pulmotoxicity of various air pollutants and harmful chemicals.

Numerically simulated behavior of diesel particulate matter emitted by hydraulic support transporters.

WC55-Y hydraulic support transporters allow an efficient transport of support equipment in fully mechanized mining faces. However, the diesel particulate matter (DPM) emitted by these transporters seriously pollutes the air environment along mine roadways, endangering the health of coal mine workers. In this paper, we simulated the diffusion dispersion of DPM during the functioning of a WC55-Y hydraulic support transporter (emitting high amounts of exhaust pollutants) by computational fluid dynamics, identifying high DPM concentration zones. While the transporter was driven along a coal auxiliary transportation roadway, the diffusion-dispersion characteristics of DPM changed: DPM reached a long horizontal diffusion distance and a high concentration. We found that to avoid the inhalation of DPM and reduce its potential harm, coal mine workers should keep a distance of at least 21.27m from the hydraulic support transporter while the vehicle runs along the roadway. Moreover, according to our simulation, the operators responsible for disassembling the hydraulic support transporter should wear protective equipment with good filterability while unloading it. Overall, the findings of this study can be applied to outline new work practice guidelines and design new optimum auxiliary ventilation for reducing underground miner exposure to DPM.

CFD numerical simulation on diffusion and distribution of diesel exhaust particulates in coal mine heading face

Diesel equipment used in underground production and transportation will produce a large amount of diesel particulate matter (DPM), which seriously pollutes the fresh air in underground and endangers the life and health of miners. In order to study the diffusion and distribution of DPM, this paper based on CFD numerical simulation technology, carries out numerical simulation of airflow and DPM field in heading face. The results show that from 15 s to 60 s, DPM continuously accumulates in the blind zone of the airflow and on both sides of the monorail locomotive, with the DPM concentration greater than 1.2 × 10−7 kg/m3. At this time, the DPM cloud is 60 m in the horizontal direction, and shows a distribution characteristic of high in the middle and low on both sides. When T = 90 s, part of DPM diffuses to the roadway exit. At this time, in the entire roadway, starting from a section of 23 m away from the heading face, the DPM concentration sharply increases, reaching a peak of 2.91 × 10-7 kg/m3 at 33 m. Then it begins to decline slowly. The research results are of great significance to clean production in mines.

A hybrid methodology for investigating DPM concentration distribution in underground mines

A hybrid methodology is proposed to investigate the diesel particulate matter (DPM) concentration distribution in underground mines by using a ventilation network solver and computational fluid dynamics (CFD). Mine ventilation system, one of the most significant and energy-intensive parts of an underground mine, needs to be accurately studied to provide sufficient fresh air to the personnel working underground. Ventilation is used to dilute and remove the contaminants out of a mine to protect the personnel from being exposed to concentrations outside of regulatory requirements. Numerical modeling is increasingly being used to assist mine ventilation design and operation. Currently, there are two types of solvers used to calculate ventilation system solutions, which are network solvers and CFD. The hybrid methodology is proposed to provide improved diesel input to a ventilation network model using CFD. The hybrid methodology combines the two solvers through commonly shared boundary conditions, making it possible to conduct mine-scale ventilation simulations. The network solver simulates the whole mine ventilation system, and CFD simulates the active working faces. In this fashion, the ventilation model is computationally efficient but still produces accurate and detailed (e.g., three-dimensional DPM concentration distribution) results. Mining operations can benefit from the updated network model using the hybrid methodology and quickly assess different ventilation plans without additional capital investments.

Behavior of diesel particulate matter transport from subsidiary transportation vehicle in mine.

The aim of this study was to investigate thoroughly the diffusion and distribution of diesel particulate matter (DPM) discharged from a mine subsidiary transportation vehicle to improve the air quality in tunnels by reducing exhaust pollution and to propose targeted prevention measures. More specifically, the diffusion of DPM from a WC40Y shield carrier during its travel was examined in depth with numerical simulations. The results show that, under the current ventilation conditions, the airflow in the tunnel was insufficient for diluting the DPM discharged from the shield carrier during starting, accelerated traveling, and turning; this can be effectively addressed by increasing the ventilation rate to 1.8m/s. However, during high-velocity travel, the carrier was affected by the piston wind could not be diluted effectively by increasing ventilation rate. The velocity limit can lower the DPM concentration in the tunnel and alleviate DPM pollution from the shield carrier. To reduce DPM emissions, the travel velocity should be limited to 30km/h. Summary: Determine the optimal airflow velocity in the tunnel that ensures that the discharged DPM is effectively diluted during the travel of the shield carrier.

Numerical investigation of diesel particulate matter dispersion in an underground development face during key mining activities

Diesel particulate matter (DPM) is carcinogenic to humans. Underground miners have a high risk of over-exposure to high concentrations of DPM. To control DPM effectively, it is essential to understand the DPM dispersion characteristics. In this study, the DPM distributions of three key and representative mining activities, shotcreting, charging and loading activity, in an underground development face were studied. A computational model for the mining activities was developed using 3D imagery, onsite data and OpenFOAM. Tracer gas experiments were first conducted in the underground mine for the validation of CFD simulation. The simulations were carried out at a steady-state using the standard k-ε turbulence model, and the transport and dispersion of DPM were modelled using a segregated species transport model. DPM distribution characteristics for each mining activity were analysed, and the regions with high concentration (>0.1 mg/m3) were identified, and the reasons for the high concentrations were also discussed. At last, the efficiency of the current auxiliary ventilation system on DPM dilution was evaluated based on the simulation results. The results show that a broader region with high DPM concentration was identified in the downstream of the loader during the loading activity, and this issue could be solved by simply increasing the ventilation rate. The findings in this paper could be used for optimizing the auxiliary ventilation design for future mining activities in this development face.

Numerical study on DPM dispersion and distribution in an underground development face based on dynamic mesh

In 2012, the International Agency for Research on Cancer (IARC) classified diesel particulate matter (DPM) as a carcinogen to human. With the increased usage of diesel equipment in underground mines, miners have a high risk of over-exposure to DPM, which has drawn many concerns from the public. This study used computational fluid dynamics (CFD) to analyse the DPM dispersion and concentration distribution characteristics in an underground development face based on an onsite experiment. The DPM emitted from a moving loader under a forcing auxiliary ventilation system was simulated. The motion of the load-haul-dump (LHD) in the tunnel was represented by a dynamic mesh method. The species transport approach was applied to study the DPM behaviours. High DPM concentration zones were then identified based on the simulation results. The results could provide guidelines for work practices and be helpful to an optimum auxiliary ventilation design to reduce underground miner exposure.

CFD simulations of DPM flow patterns generated by vehicles in underground mines for different air flow and exhaust pipe directions

In this paper, an attempt is made to model diesel particulate matter (DPM) flows generated by load haul dumpers (LHDs) and trucks in an underground mine environment for different DPM flow and intake air flow directions and exhaust pipe directions. The results obtained show that the DPM concentration near the vehicle was dependent on exhaust pipe location and direction. If the exhaust pipe is located at the rear or the top of the vehicle, the vehicle operator may be susceptible to exposure to high concentrations of DPM. If the exhaust pipe is located at the bottom of the vehicle, the operator is less likely to be exposed to high concentrations of DPM. Finally, at 10 m downstream of the loading bay the very high concentrations DPM particles tend to spread over the entire cross section of the roadway.

DPM flow pattern of LHD in underground mines with different ventilation conditions

Diesel-operated Load Haul Dumper (LHD) vehicles are commonly used in underground coal mines. Despite their value as utility vehicles, the main drawback of these vehicles is that they generate diesel particulate matter (DPM), a known carcinogenic agent. In this work, an attempt is made to model DPM flows generated by LHDs in an underground coal mine environment for different DPM flow and intake air flow directions. The field experiments are conducted and used to validate the computational fluid dynamics (CFD) models and used to map the DPM flow patterns. The results obtained show that if DPM and the intake air co-flow (flow in the same direction), DPM is confined predominantly in the middle of the roadway. To the contrary, if the DPM and intake air counter-flow (flow in the opposite directions), the DPM spread occurs throughout the entire cross-section of the roadway. In the latter case, the operator will be more susceptible to exposure to high concentrations of DPM. Overall, the DPM concentration decreases with an increase in the intake air velocities. For co-flow for intake air velocities of 2 m/s, 3 m/s, and 4 m/s, the DPM concentrations at 50 m downstream of the vehicles are 39 µg/m3, 23 µg/m3, and 19 µg/ m3, respectively. The DPM concentration is also influenced by the DPM temperature at the source. For the DPM temperatures of 30 oC, 40 oC, 50 oC, and 60 oC, the DPM concentrations at 50 m downstream of the source are 43 µg/m3, 34 µg/m3, 12 µg/m3, and 9 µg/m3, respectively.

Comparison of underground mine DPM simulation using discrete phase and continuous phase models

Diesel particulate matter (DPM) is carcinogenic to humans. DPM concentrations in underground mines are much higher than other working environments, thus pose substantial health threats to miners due to overexposure. Computational fluid dynamics is commonly used to study the DPM dispersion and assess the concentration distribution in various working environments. However, most such studies for underground mines treated DPM as a continuous phase (gas phase) in the model. DPM is a solid discrete phase, and its behaviours could be quite different from that of gaseous contaminants. This study compared DPM concentration distributions by using three modelling methods: the Eulerian-Lagrangian method and the Eulerian-Eulerian method that treats DPM as discrete phase particles, and the species transport method that treats DPM as a continuous phase gas. The model was based on a typical underground mine development face with a forcing auxiliary ventilation setup. It was found that the general DPM concentration distribution for the three numerical methods was similar for simple geometry with more uniform flow regions. However, large discrepancies existed in the development heading with complex geometry and flow features. The findings suggest that when simulating DPM, although the species transport method can provide relatively accurate results with much less computational time, the parameters of the modelled gas need to be carefully calibrated to get a better simulation result. For key areas where the diesel machinery and miners are usually located, the Eulerian-Lagrangian method should be used for more accurate analysis.

Minimizing DPM pollution in an underground mine by optimizing auxiliary ventilation systems using CFD

Diesel particulate matter (DPM) is a carcinogen to humans. Underground miners have the potential to expose to higher DPM concentrations since the working environment is confined. To address the DPM pollution issues and optimize the auxiliary ventilation system, a development face in an underground mine in Western Australia was taken as the physical model and the computational fluid dynamics was used to analyse the airflow characteristics and DPM concentration distributions in the development face. Then, the obtained simulation results were validated with the onsite measurement data. The DPM concentration distributions under 3 scenarios, with different duct lengths, were further compared with the AIOH standard for DPM (0.1 mg/m3). The results found that the current auxiliary ventilation system was not able to reduce the DPM concentration effectively, and the ventilation system with a duct length 5 m longer than the actual duct length provided a better DPM dilution performance. The finding of this paper is helpful for effective DPM control and auxiliary ventilation design for the further mining activities.

Numerical study of diesel particulate matter distribution in an underground mine isolated zone

The increased use of diesel engines in underground mines, together with increased mine depth, cause challenges in maintaining diesel particulate matter (DPM) at acceptable levels in underground environments. In 2012, the International Agency for Research on Cancer (IARC) classified DPM as carcinogenic to humans. To control the DPM exposure, it is important to understand DPM distribution and dispersion characteristics. In this study, an isolated zone in an underground mine in the US was taken as the physical model and the computational fluid dynamics (CFD) method was used to study the DPM distribution for two operational scenarios. The simulation results were compared with existing validation data. Compared to studies that treat DPM as a continuous phase, a better agreement with the experimental data is achieved in this study which uses the discrete phase to represent DPM. High DPM concentrations were identified in the two scenarios. This information can be potentially used to optimise auxiliary ventilation designs.

Diesel engine exhaust exposure in underground mines: Comparison between different surrogates of particulate exposure

ABSTRACTExposure to diesel particulate matter (DPM) is frequently assessed by measuring indicators of carbon speciation, but these measurements may be affected by organic carbon (OC) interference. Furthermore, there are still questions regarding the reliability of direct-reading instruments (DRI) for measuring DPM, since these instruments are not specific and may be interfered by other aerosol sources. This study aimed to assess DPM exposure in 2 underground mines by filter-based methods and DRI and to assess the relationship between the measures of elemental carbon (EC) and the DRI to verify the association of these instruments to DPM. Filter-based methods of respirable combustible dust (RCD), EC, and total carbon (TC) were used to measure levels of personal and ambient DPM. For ambient measurements, DRI were used to monitor particle number concentration (PNC; PTrak), particle mass concentration (DustTrak DRX and DustTrak 8520), and the submicron fraction of EC (EC1;Airtec). The association between ambient EC and the DRI was assessed by Spearman correlation. Geometric mean concentrations of RCD, respirable TC (TCR) and respirable elemental EC (ECR) were 170 µg/m3, 148 µg/m3, and 83 µg/m3 for personal samples, and 197 µg/m3, 151 µg/m3, and 100 µg/m3 for ambient samples. Personal measurements had higher TCR:ECR ratios compared to ambient samples (1.8 vs. 1.50) and weaker association between ECR and TCR. Among the DRI, the measures of EC1 by the Airtec (ρ = 0.86; P < 0.001) and the respirable particles by the DustTrak 8520 (ρ = 0.74; P < 0.001) showed the strongest association with EC, while PNC showed a weak and non-significant association with EC. In conclusion, this study provided important information about the concentrations of DPM in underground mines by measuring several indicators using filter-based methods and DRI. Among the DRI, the Airtec proved to be a good tool for estimating EC concentrations and, although the DustTrak showed good association with EC, interferences from other aerosol sources should be considered when using this instrument to assess DPM.

Measurement of area and personal breathing zone concentrations of diesel particulate matter (DPM) during oil and gas extraction operations, including hydraulic fracturing

ABSTRACTDiesel engines serve many purposes in modern oil and gas extraction activities. Diesel particulate matter (DPM) emitted from diesel engines is a complex aerosol that may cause adverse health effects depending on exposure dose and duration. This study reports on personal breathing zone (PBZ) and area measurements for DPM (expressed as elemental carbon) during oil and gas extraction operations including drilling, completions (which includes hydraulic fracturing), and servicing work.Researchers at the National Institute for Occupational Safety and Health (NIOSH) collected 104 full-shift air samples (49 PBZ and 55 area) in Colorado, North Dakota, Texas, and New Mexico during a four-year period from 2008–2012. The arithmetic mean (AM) of the full shift TWA PBZ samples was 10 µg/m3; measurements ranged from 0.1–52 µg/m3. The geometric mean (GM) for the PBZ samples was 7 µg/m3. The AM of the TWA area measurements was 17 µg/m3 and ranged from 0.1–68 µg/m3. The GM for the area measurements was 9.5 µg/m3. Differences between the GMs of the PBZ samples and area samples were not statistically different (P > 0.05).Neither the Occupational Safety and Health Administration (OSHA), NIOSH, nor the American Conference of Governmental Industrial Hygienists (ACGIH) have established occupational exposure limits (OEL) for DPM. However, the State of California, Department of Health Services lists a time-weighted average (TWA) OEL for DPM as elemental carbon (EC) exposure of 20 µg/m3. Five of 49 (10.2%) PBZ TWA measurements exceeded the 20 µg/m3 EC criterion. These measurements were collected on Sandmover and Transfer Belt (T-belt) Operators, Blender and Chemical Truck Operators, and Water Transfer Operators during hydraulic fracturing operations.Recommendations to minimize DPM exposures include elimination (locating diesel-driven pumps away from well sites), substitution, (use of alternative fuels), engineering controls using advanced emission control technologies, administrative controls (configuration of well sites), hazard communication, and worker training.

A review of the health effects and exposure-responsible relationship of diesel particulate matter for underground mines

The increasing use of diesel-powered equipment in confined spaces (underground mines) has the potential to over expose underground miners under the threat of diesel particulate matter (DPM). Miners in underground mines can be exposed to DPM concentrations far more than works in other industries. A great number of animal and epidemiological studies have shown that both short-term and long-term DPM exposure have adverse health effect. Based on reviews of related studies, especially some recent evidence, this paper investigated the long and short-term health effects based on animal studies and epidemiological studies. The exposure-response relationship studies were also explored and compared to the current DPM regulation or standards in some countries. This paper found that the DPM health effect studies specifically for miners are not sufficient to draw solid conclusions, and a recommendation limit of DPM concentration can be put in place for better protection of miners from DPM health risk. Current animal studies lack the use of species that have similar lung functions as human for understanding the cancer mode of action in human. And finally, the DPM health hazard will continue to be a challenging topic before the mode of action and reliable exposure-response relationship are established.