Respirable Dust Concentrations Research Articles

Influence of environmental parameters on workers' dust inhalation in underground mines.

Much dust is generated in underground coal mining processes, posing threats to workers' health and safety production. Dust enters the human body mainly through inhalation, primarily determined by the dust concentration around workers. In this study, the airflow field and dust distribution in the tunnel are simulated with FLUENT software. The breathing zone for a worker was defined to clarify the extent of external dust distribution influencing dust inhalation. The effects of human respiration, dust production rates, air supply velocities, and workers' positions on dust concentration in the breathing zone were investigated. The results show that there is upward airflow around the worker standing in the center of the air circulation. Human breath barely influences the airflow distribution and respirable dust concentrations in the breathing zone. Reducing the dust production rate in the tunnel can decrease the respirable dust concentration in the breathing zone by almost the same proportion. While increasing the air supply velocity by 50% would reduce only 20% of dust in the breathing zone. The dust concentrations vary along the roadway, in which the low concentration zone is located in the middle, more than 1.0m away from the dust-producing surface and the wind surface. The research contributes to reducing workers' dust exposure with suggestions regarding ventilation optimization and working position selection.

Dynamic–static intermittent pressurized-water injection in gas-drainage boreholes for dust reduction

Serious dust pollution that occurs during production at a fully mechanized working face in a soft outburst coal seam is addressed. Dynamic–static intermittent pressurized-water injection was applied for dust reduction using gas-drainage boreholes. Under production conditions, the optimal duration of a single cycle was 4 h of dynamic injection, a 2 h interval during which no pressure was applied, followed by 6 h of static injection. After water injection for almost 60 h, dust production by the coal body decreased by 43.06% compared with the same coal body without water injection: the particle size range of the dust also decreased. Total and respirable dust concentrations at measuring points in the vicinity of the working face were reduced by 56.69% and 55.53%, respectively, on application of dynamic–static intermittent pressurized-water injection, indicating that this technology is effective in suppressing coal-mining dust production.

Investigation on optimal selection of multi-nozzle spray dust suppression parameters for air-operated spraying system

To evaluate the granularity distribution pattern for multi-nozzle interference spray, the two-phase flow state inside the nozzle and the fragmentation process of the droplet particles in the eddy current field is studied, and the atomization characteristics of the multi-nozzle spray interference process is simulated based on CFD technology. The results indicate that the braking distance in the atomization field decreases with the increase of atomization pressure, and the decreasing speed is slower, in contrast, the atomizing angle increases with the rise in atomization pressure and the decrease of nozzle diameter. Compared with the single nozzle atomization field, the multi-nozzle atomization field has a more uniform distribution of droplet particles through collision, polymerization and rupture, which can achieve a better dust removal effect. By increasing the atomization pressure, the multi-nozzle interference atomization area can be formed faster, the droplet size is more refined, and the distribution is more uniform. Under the optimal parameters, practical testing indicates that the multi-nozzle air-operated atomization system makes the total dust and respirable dust concentrations at the various measuring points decrease rapidly, and the maximum suppression rates reach 95.52% and 96.84%, respectively.

Performance optimization and experimental analysis of angle grinder with dust collection hood

The grinding process of the angle grinder generates a large amount of dust, which present hazards to the environment and workers' health. In order to capture the grinding dust more efficiently, this paper optimizes the performance of the dust collection hood of the angle grinder by building a grinding experimental platform and using the response surface method (RSM). Using the Box-Behnken design method, the collection quantity Mtotal of all dust particles generated by grinding and the collection quantity MPM10 of PM10 are used as the main performance indicators of the dust collector. Four independent factors such as grinding wheel diameter, suction pipe diameter, mounting angle, and grinding wheel speed of the dust collection hood were optimized to arrive at the best combination of parameters. Through response surface analysis, a quadratic polynomial regression model between each influencing factor and performance indicator is established, and significance test and variance analysis are performed to verify the validity and applicability of the model. Finally, through three-dimensional response surface plots and contour plots, the interactions between each influencing factor are analyzed, and the predicted values of performance indicators under optimal experimental conditions are determined. The experimental results show that the mounting angle has the greatest impact on Mtotal, and the grinding wheel speed has the greatest impact on MPM10. The field engineering application shows that the optimized dust collection hood can effectively prevent dust from escaping. The reduction efficiency of total dust concentration in the grinding place is over 83.6 %, and the reduction efficiency of respirable dust concentration is over 90.0 %. The research results of this paper provide some reference value for the research and application in the field of dust control.

Dust diffusion laws during partition excavation by boom-type roadheader in a metro tunnel

When the drill bit of the boom-type roadheader cuts the dolomite at the tunnel face, it generates a lot of dust, which will have an adverse impact on human health and the surrounding environment. In order to clarify the laws of dust diffusion during partition excavation by a boom-type roadheader in a metro tunnel, the respirable dust and particle size distribution characteristics of tunnelling dust are studied through field experiments. Combined with FLUENT numerical simulation, the axial and radial diffusion laws of dust in the air field and the upper and lower parts of the tunnel face are further explored. The results show that at a position 5 m away from the tunnel face, the excavation dust concentration in the lower partition is 65.88% higher than that in the upper partition, and the concentration of respirable dust reaches 313.46 mg/m3, which has a greater impact on a boom-type roadheader operator. In the simulated excavations in the upper and lower partitions, the optimal distance between the air duct outlet and tunnel face is 12 m and 15 m, respectively, and 550 m3/min is the optimal pressure airflow.

Research and application of self-powered induction spray dust removal system for long-distance belt conveying in underground coal mines

A self-powered induction spray dust removal system for long-distance belt conveying in underground coal mines was developed. In the system, the kinetic energy of the conveyor belt can be converted into the electrical energy required by the infrared sensing atomization spray device. When the rotational speed of the roller reaches 230 r/min, 12.33 V electricity can be steadily generated. Further proposed to install multiple sets of dust reduction systems with an optimal spacing of 240 m. The effectiveness of this installation method was verified by turning systems on one by one in the 25211 transportation roadway of the Hongliulin coal mine. The total dust concentration was reduced from 11.78 mg/m3 to 3.88 mg/m3, and the respirable dust concentration was reduced from 6.33 mg/m3 to 2.48 mg/m3. The results show that the developed self-powered induction spray dust removal system can dramatically improve the long-distance belt conveying environment in coal mines.

Investigation of the Tendency of Carbon Fibers to Disintegrate into Respirable Fiber-Shaped Fragments

Recent reports of the release of large numbers of respirable and critically long fiber-shaped fragments from mesophase pitch-based carbon fiber polymer composites during machining and tensile testing have raised inhalation toxicological concerns. As carbon fibers and their fragments are to be considered as inherently biodurable, the fiber pathogenicity paradigm motivated the development of a laboratory test method to assess the propensity of different types of carbon fibers to form such fragments. It uses spallation testing of carbon fibers by impact grinding in an oscillating ball mill. The resulting fragments were dispersed on track-etched membrane filters and morphologically analyzed by scanning electron microscopy. The method was applied to nine different carbon fiber types synthesized from polyacrylonitrile, mesophase or isotropic pitch, covering a broad range of material properties. Significant differences in the morphology of formed fragments were observed between the materials studied. These were statistically analyzed to relate disintegration characteristics to material properties and to rank the carbon fiber types according to their propensity to form respirable fiber fragments. This tendency was found to be lower for polyacrylonitrile-based and isotropic pitch-based carbon fibers than for mesophase pitch-based carbon fibers, but still significant. Although there are currently only few reports in the literature of increased respirable fiber dust concentrations during the machining of polyacrylonitrile-based carbon fiber composites, we conclude that such materials have the potential to form critical fiber morphologies of WHO dimensions. For safe-and-sustainable carbon fiber-reinforced composites, a better understanding of the material properties that control the carbon fiber fragmentation is imperative.

Comparing PM2.5, respirable dust, and total dust fractions using real-time and gravimetric samples in an exposure chamber study

Using an exposure chamber, we investigate the precision of the DustTrak DRX monitor by comparing its results to those obtained from taking traditional gravimetric samples of two stone minerals commonly used in asphalt and lactose powder. We also discuss the possibility of using real-time monitors such as DustTrak DRX for occupational exposure monitoring purposes.The results are based on 19 days of experiment, each day with measurements collected over 4 h. Compared to the gravimetric samples, the DustTrak DRX overestimated the PM2.5 and respirable dust concentrations, while it underestimated the total dust concentration by a factor of nearly two. However, the ratios, being done for more than one material, between the DustTrak DRX and the gravimetric sample readings varied daily and across the different exposure materials.Real-time sensors have the potential to excel at identifying exposure sources, evaluating the measured control efficiency, visualizing variations in exposure to motivate workers, and contributing to the identification of measures to be implemented to reduce exposure. For total dust, a correction factor of at least two should be used to bring its readings up to those for the corresponding gravimetric samples. Also, if the DustTrak DRX is used in the initial profiling of occupational exposure, the exposure could be considered acceptable if the readings are well below the occupational exposure limit (OELs) after correction. If the DustTrak DRX readings, after correction, is close to, or above, the accepted exposure concentrations, more thorough approaches would be required to validate the exposure.

146 Meteorological Influence on Measurement Strategy and Estimated Respirable Dust and Respirable Crystalline Silica Exposure Levels Within the European Minerals Industry

Abstract The evidence of meteorological conditions on occupational exposure measurements is limited, despite is expected to be important determinants of long-term exposures. We describe meteorological conditions for measurement and non-measurement days and evaluate associations between temperature and total precipitation and respirable dust and respirable crystalline silica (RCS) concentrations of the European Industrial Minerals Association-Dust Monitoring Programme. Geo-matched RCS and dust measurements were evaluated against meteorological data (archived satellite observations and weather station measurements). Temperature(0C) and total precipitation (mm) for RCS measurement and non-measurement days were described. A linear regression model was used to investigate the association between dust and RCS concentration and meteorological conditions. Overall, 2,840 dust measurements (GM=0.20mg/m3; GSD=3.43mg/m3) and 2,658 quartz measurements (GM=0.01mg/m3; GSD=5.23mg/m3) were collected across 96 an 94 industrial mineral sites over 262 and 259 days in 2011. Mean temperature and precipitation for dust and RCS measurements were similar for measurement and non-measurement days (dust: 10.490C and 10.830C, 2.23mm and 2.12mm; RCS: 11.050C and 10.820C, 2.08mm and 2.12mm). For respirable dust concentrations a 6.4% decrease per 1°C was estimated for temperatures<200C (p<0.001) and an 8.2% increase for temperatures≥200C (p=0.002). For RCS a 2% decrease in was estimated for every 1mm increase in total precipitation (p=0.02). No difference in meteorological conditions were seen between measurements days and non-measurement days. Associations of these conditions with exposure concentrations with showed differences between agents despite being collected and measured on the same filter. Long-term changes in meteorological conditions might be an important factor when estimating long term exposures.

108 Workplace Exposure to Ultrafine Particles, Dust, and Chemicals During Plastic Production with Recycled Plastics

Abstract The plastics industry is a major contributor to the world economy, and in 2019 alone, there were some 480 million metric tons of plastic produced worldwide. Although a great deal of attention has been given to measuring and understanding the extent of plastic in the environment and its associated human exposure, much less is known about the human exposure to plastics during its production. The aim of this study is to characterize in detail the particulate matter (PM) emitted from various processes involved in the manufacturing and recycling of plastics. Here we report our findings from an initial campaign carried out at a Danish plastics factory. Online instruments were used to determine the particle number and mass concentrations for particles in the range of 10nm to 10µm, over the course of five hours, at both near- and far-field positions with respect to activities associated with the processing of plastics, including extruding, thermoforming, mixing, crushing, and rolling. For fine particles (<300nm), the average total particle number concentrations associated with these activities were 3.3x104, 4.0x103, 2.8x104, 3.5x104, and 6.9x104 #/cm3, respectively. Respirable dust concentrations were 13, 7, 9, 7 (calculated), and 12 µg/m3, respectively, and total dust concentrations were similar or slightly higher. These data suggest that the principal contributions to human exposure in the facility are fine and ultrafine particles. In addition to the real-time data and mass concentrations, samples are also analyzed for elemental composition and plastics. This research was supported by FFIKA, a grant from the Danish government.

106 Investigation of Workplace Silica Exposures Using Novel Samplers and Methods

Abstract Scientists from the Health and Safety Executive visited a manufacturing workplace where coatings are prepared by loading powders, frit and water into various sized mills. The aim of the visit was to determine potential worker exposures to dust and respirable crystalline silica by static air monitoring and exhaled breath condensate. Low-cost particle monitors were deployed alongside more established scientific equipment. Airborne dust concentrations were measured at three site locations using two photometers, an optical particle counter (OPC) and a respirable cyclone. The size distribution was measured in real-time using a low-cost OPC and by offline analysis of a polycarbonate membrane filter housed inside an inhalable sampler. Pre and post shift samples of exhaled breath condensate were collected from 6 workers, with samples analysed by single particle inductively coupled plasma mass spectrometry to measure the number and size of silicon containing particles present. The real-time air monitoring data at all three locations showed peaks in airborne concentrations corresponding to the loading activities and indicating the tasks most likely to contribute to worker exposure. The average concentration of respirable dust measured closest to the process was 0.13 mg.m-3 for the 8-hour shift. The low-cost monitors provided good information about the changes in concentration over time relating to worker activities.

29 Estimating Respirable Dust Exposure from Inhalable Dust Exposure

Abstract From the exposition database ‘MEGA’, established by the Institute for Occupational Safety and Health of the German Social Accident Insurance, measurements of inhalable dust (n=103 825) and respirable dust (n=222 501) were selected to create conversion functions of inhalable to respirable dust concentrations in different workplaces. These functions are important for exposure assessment or retrospective evaluations of exposure situations and for epidemiologic studies, when just one fraction was analyzed. For the determination of the conversion functions, 15 120 pairs of inhalable and respirable dust, which were measured in parallel, were formed. The assignment was done considering various variables such as sampling date and time or workplaces. The measured values were log-transformed and a linear regression analysis was done, calculating a conversion function for the whole dataset with an adjusted R2 > 0.580 and R>0.760. On the basis of technical information, the dataset was divided into different dust groups considering material and working activities as relevant variables, resulting in six working activity, three material, four working activity-material combination and eleven heuristic groups. For each of these groups a conversion function was calculated as well and will be described in the presentation. The models admissibility was evaluated by examining the assumptions of linear regression such as no autocorrelation, normal distribution of residuals and variance homogeneity. On the basis of that, future measurements in different workplaces and the dust exposure can easier be evaluated, when measurements of just one fractions were made and the other can be estimated using the conversion functions.

Mineralogical Study of Respirable Dust in Artisanal SmallScale Quarries of Misisi Compound, Lusaka, Zambia

Misisi compound in Lusaka is characterized by artisanal small scale quarrying activities which are often dusty in nature and prone to hazards. This study reports respirable dust concentration and the mineralogical composition of rocks in the workplace. Dust sampling was carried out with the help of gravimetric samplers at five quarries. Respirable dust samples were collected during digging, chiselling, crushing, and loading sites. The results of the sampled dust indicated high levels of respirable dust at all five quarry crushing sites. For example, based on Time Weighted Average (TWA), the respirable dust concentration at the crushing site was recorded as 12.75 mg/m3 at quarry#1 compared to the Maximum Allowable Concentration (MAC) of 5 mg/m3 of Occupational Safety and Health Administration (OSHA). The results of mineralogical testing and analyses revealed that marble was the common rock type that was being mined by most of the ASMs in the studied area. Based on the point count data analysis, marble contained 98% CaCO3 and 2% SiO2.

Characteristics of thermally modified hardwood dust in determining workers’ occupational exposure

Thermal modification of wood changes its mechanical properties, generally reducing its strength, such that it is more easily chipped during processing than untreated hardwood. This study presents specific parameters used in the determination of mass concentration of thermally modified (TM) hardwood by gravimetric and photometric methods. An optical device, the Split 2, was used in the active mode, of which the holder of the inhalable dust IOM (Institute of Occupational Medicine) filter was the input part. Side-by-side determination of the respirable and inhalable mass concentration was made using the Higgins-Dewell respirable dust cyclone and an inhalable dust IOM sampler. Side-by-side determination of inhalable and total dust mass concentration was made using an IOM and open-faced (OF) filter holder to establish an IOM / OF sampling ratio. A correction factor of 1.16 was calculated for applying the photometric method as the ratio of mass concentration determined by gravimetric and photometric methods. Minimal concentrations of respirable and inhalable wood dust (geometric mean: cr = 0.058 mg/m3; cinh = 0.882 mg/m3) and a 12.76% share of respirable dust in the inhalable concentration cr / cinh, had a significant influence on the efficiency of the photometric method. The mass concentration obtained by IOM and OF samplers did not significantly differ (p = 0.36).

Risk Assessment of Respirable Dust Exposure to Workers in the Mineral Ore Processing Industry

Introduction: The mineral ore processing industry is a sector that can generate pollutants in the form of dust during the production, commonly known as respirable dust. This dust can enter the upper respiratory tract and lungs, thereby causing health problems to employees working in the mineral ore processing industry. This study aims to investigate health risks associated with exposure to dust in the mineral ore processing industry. Methods: Environmental Health Risk Analysis (EHRA) was used to assess dust exposure over the previous three years, following the NIOSH Manual of Analytical Methods (NMAM) 0600 for dust sampling measurement. Results: Seven locations with high dust emissions were considered for this study. The results of the respirable dust sampling showed that the concentrations in the previous three years ranged from 1,823 to 6,109 mg/m3, followed by a decrease in the following year to 0.049 to 2,715 mg/m3. Meanwhile, in the final year, the concentration of respirable dust ranged from 0.094 to 1.341 mg/m3. The calculated risk quotient (RQ) value for the previous three years remained below 1, indicating safety. Conclusion: Athough respirable dust was considered safe in the previous year, it is important to constantly control exposure due to continued high levels and the possibility of future increases

Health damage assessment of reconstruction dust from old industrial buildings under multi-process.

The regeneration of old industrial buildings produces considerable construction dust, thereby seriously threatening the occupational health of construction workers. The existing articles concerning the exposure and health impacts of reconstruction dust in enclosed spaces are limited, but this research field has received increasing attention. In this study, multi-process during the demolition and reinforcement stages of a reconstruction project were monitored to determine the respirable dust concentration distribution. A questionnaire survey was conducted to obtain the exposure parameters of reconstruction workers. Moreover, a health damage assessment system for the reconstruction process of old industrial buildings was established by applying the disability-adjusted life year and human capital method to explore the health damage caused by the generated dust at different stages to the construction personnel. The assessment system was applied to the reconstruction stage of an old industrial building regeneration project in Beijing to obtain dust health damage values for different work types and to conduct comparative analysis. The results indicate that there are significant differences in the dust concentration and health damage at different stages. During the demolition stage, the manual demolition of concrete structures has the highest dust concentration, reaching 0.96mg/m3. This exceeds the acceptable concentration by 37%, and the health damage cost is 0.58 yuan per person per day. In the reinforcement stage, the dust concentration generated by mortar/concrete mixing is the highest, but the risk level is acceptable. The health damage cost of concrete grinding, which is 0.98 yuan per person per day, is the highest. Therefore, it is necessary to strengthen the protective facilities and improve the reconstruction technology to reduce dust pollution. The results of this study can help in improving the existing dust pollution control measures at construction sites to reduce the risk of dust hazards during reconstruction.

Normalized modeling of airflow-respirable dust migration and distribution in drilling construction tunnels with different cross-sections

Underground construction mainly relies on drilling work. A large amount of dust generated at the drilling location considerably increases the dust concentration in the worker's breathing area. To explore the distribution of respirable dust during the drilling construction, the virtual point source method was selected and extended to establish the theoretical distribution models for tunnels with curved edge cross-sections, and the assumed parameters in the theoretical models were determined via nonlinear fitting with Euler-Lagrange numerical dust migration field generated by drilling construction. The experimental data and theoretical results agree well based on dimensionless analysis, which verifies the validity of the built models. The respirable dust concentration prediction model curves show that the migration process of dust generated by drilling construction in tunnels encompasses free diffusion section phases, restricted diffusion section phases and full diffusion section phases along the tunnel airway, and the corresponding dimensionless distance ranges are 0–5, 5–20 and beyond 20. For the convenience of engineering application, a dimensionless normalization model is proposed based on the established theoretical models. When the ventilation velocity is between 0.4 m/s and 3 m/s, the recommended values of normalization parameters are 0.80, 0.77 and 1.81, respectively. The abovementioned research results reveal that the established effective theoretical prediction model provides a reliable theoretical basis to gain an in-depth understanding of dust migration behavior during drilling construction.

Investigation of respirable coal mine dust (RCMD) and respirable crystalline silica (RCS) in the U.S. underground and surface coal mines

Dust is an inherent byproduct of mining activities that raises notable health and safety concerns. Cumulative inhalation of respirable coal mine dust (RCMD) and respirable crystalline silica (RCS) can lead to obstructive lung diseases. Despite considerable efforts to reduce dust exposure by decreasing the permissible exposure limits (PEL) and improving the monitoring techniques, the rate of mine workers with respiratory diseases is still high. The root causes of the high prevalence of respiratory diseases remain unknown. This study aimed to investigate contributing factors in RCMD and RCS dust concentrations in both surface and underground mines. To this end, a data management approach is performed on MSHA’s database between 1989 and 2018 using SQL data management. In this process, all data were grouped by mine ID, and then, categories of interests were defined to conduct statistical analysis using the generalized estimating equation (GEE) model. The total number of 12,537 and 9050 observations for respirable dust concentration are included, respectively, in the U.S. underground and surface mines. Several variables were defined in four categories of interest including mine type, geographic location, mine size, and coal seam height. Hypotheses were developed for each category based on the research model and were tested using multiple linear regression analysis. The results of the analysis indicate higher RCMD concentration in underground compared to RCS concentration which is found to be relatively higher in surface coal mines. In addition, RCMD concentration is seen to be higher in the Interior region while RCS is higher in the Appalachia region. Moreover, mines of small sizes show lower RCMD and higher RCS concentrations. Finally, thin-seam coal has greater RCMD and RCS concentrations compared to thicker seams in both underground and surface mines. In the end, it is demonstrated that RCMD and RCS concentrations in both surface and underground mines have decreased. Therefore, further research is needed to investigate the efficacy of the current mass-concentration-based monitoring system.

Temporal Trends in Variability of Respirable Dust and Respirable Quartz Concentrations in the European Industrial Minerals Sector.

While between- and within-worker variability have been studied quite extensively, hardly any research is available that examines long-term trends in the variability of occupational exposure. In this first study on trends in occupational exposure variability temporal changes in the variability of respirable dust and respirable quartz concentrations within the European industrial minerals sector were demonstrated. Since 2000 the European Industrial Minerals Association's Dust Monitoring Program (IMA-DMP) has systematically collected respirable dust and respirable quartz measurements. The resulting IMA-DMP occupational exposure database contains at present approximately 40 000 personal full-shift measurements, collected at 177 sites owned by 39 companies, located in 23 European countries. Repeated measurements of workers performing their duties within a specific site-job-campaign combination allowed estimation of within- and between-worker variability in exposure concentrations. Overall day-to-day variability predominated the between-worker variability for both respirable dust concentrations and quartz concentrations. The within-worker variability in concentrations by job was two to three times higher for respirable quartz than for respirable dust. The median between-worker variability in respirable dust concentrations was low and further reduced over time. For quartz concentrations the same phenomenon albeit somewhat less strong was observed. In contrast, for the within-worker variability in concentrations downward and upward temporal trends were apparent for both respirable dust and respirable quartz. The study shows that the (relative) size of temporal variability is large and unpredictable and therefore regular measurement campaigns are needed to ascertain compliance to occupational exposure limit values.

Metal Exposure-Related Welder's Pneumoconiosis and Lung Function: A Cross-Sectional Study in a Container Factory of China.

Long-term inhalation of welding fume at high exposure can cause welder's pneumoconiosis, and metals in welding dust are associated with respiratory dysfunction. This cross-sectional study, which contains 384 Chinese male workers who were or had been working in a container factory, aimed to assess the potential risk of haemal and urinary metal content in welder's pneumoconiosis. Further, we investigated their effects on lung function parameters. Metal content and lung function were measured using inductively coupled plasma-mass spectrometry (ICP-MS) and spirometer, respectively. The concentration and metal content of respirable dust as well as total dust were collected at this container factory. Lung function of cases with welder's pneumoconiosis was significantly worse, as indicated by lower values of FVC, FVC% predicted, FEV1, FEV1% predicted, MEF25% predicted, and MMEF% predicted (p < 0.05). Results of logistic regression models showed that haemal Cr and Zn were risk factors of welder's pneumoconiosis (OR = 4.98, 95%CI: 1.73-21.20, p = 0.009 for Cr; OR = 5.23, 95%CI: 1.56-41.08, p = 0.033 for Zn) after adjusted with age, BMI, working years, welding dust exposure years, and smoking status. Multiple linear regression models showed that several metals (haemal Cd and Pb; urinary Cd and Fe) were significantly associated with different lung function indices in the welder's pneumoconiosis group. Compared to non-welders, welders were exposed to considerably higher levels of respirable dust, total dust, and six kinds of metals (p < 0.05). In conclusion, haemal Cr and Zn are positively related to welder's pneumoconiosis. Meanwhile, Cd and Pb might worsen lung function in welder's pneumoconiosis.