Respirable Dust Concentrations Research Articles

Measurements of dust and respirable crystalline silica during indoor demolition and renovation.

Increased focus on renovating and maintaining the existing building stock is an integral part of the circular economy, however this might pose challenges to workers health. The aim of this study was to assess the renovation workers' exposure to inhalable dust, thoracic dust, respirable dust, and respirable crystalline silica (RCS). Personal aerosol samples were collected as full shift samples from 92 workers to a total of 407 samples. Fourteen locations around Oslo, Norway was visited for multiple days with repeated measurements of the same individual. Particulate matter from 3 aerosol fractions, respirable, thoracic, and inhalable, were analyzed gravimetrically, and the respirable fraction was analyzed for RCS by NIOSH 7500 method for X-ray diffraction (XRD)with low temperature plasma ashing sample preparation. The total measured concentrations of respirable dust (n = 192) had a geometric mean (GM) of 0.88mg/m3, RCS concentrations (n = 182) had a GM of 0.040mg/m3, thoracic dust (n = 131) had GM 2.4mg/m3, and inhalable dust (n = 84) had a GM of 8.5mg/m3. The maximum measured concentrations were 29mg/m3, 3.2mg/m3, 65mg/m3, and 163mg/m3, respectively. Workdays involving tasks such as mechanical demolition and clearing out demolished materials led to the highest exposure levels of both dust and RCS. However, other workers at the renovation sites were indirectly exposed to a considerable amount of RCS. This study revealed substantial exposure to both RCS and dust during renovation, and protective measures are warranted to reduce exposure levels in the industry.

Exposure to cooking fumes in cafeteria workers in Korean schools: a pilot study.

This study measured cooking fumes to which workers in school cafeterias may be exposed. The measurement items were respirable dust, formaldehyde, and carbon monoxide. A total of 111 samples were obtained from 55 schools. Data on variables such as school size and daily cooking oil usage were collected. Correlation and association analysis were performed. The median of concentrations of respirable dust was 38.37 µg/m3 (min-max: 20.73-49.71 µg/m3). The concentrations of formaldehyde and carbon monoxide also showed levels that did not exceed 20% for occupational exposure limits. The increase in school size was significantly correlated with the increase in daily cooking oil usage and had a significant correlation with respirable dust concentration (Spearman's correlation coefficient, 0.36; P <0.05). The linear regression test results adjusting for other variables were also similar. Cooking food by frying at high heat using cooking oil can increase the exposure of kitchen workers to respirable dust.

Indoor/Outdoor particulate matter (respirable dust) and respirable crystalline silica source tracking in households located proximal to gold mine tailings in Johannesburg, South Africa

Introduction: This study aimed to investigate the concentration of Respirable Crystalline Silica (RCS) and respirable dust, Particulate matters (PM4) concentration in samples measured indoors and outdoors of the nine(9) selected households located proximal to gold mine tailings in Riverlea, Johannesburg. Materials and methods: Sampling locations were separated according to grids, based on distance from the tailings; A (&lt;500 m from the dump), B (&gt;500m&lt;1 km) and C (1 km-3 km). Three households were selected from each grid zone to measure indoor and outdoor PM4 samples continuously over 24 h using GilAir constant sampling pumps. Samples were collected during dry and wet seasons, and respirable crystalline silica in PM4 samples were analysed by an X-ray diffraction method. Results: The mean indoor and outdoor PM4 mass concentrations ranged from 2.02±0.02 µg/m3 to 2.26±0.02 µg/m3, respectively. The dry season mean for PM4 mass concentrations were higher than the wet season PM4 mass concentrations in all zones. The pairwise comparison of PM4 mass concentration for dry and wet seasons revealed no statistically significant difference (p&lt;0.05). The dry season means the indoor/outdoor ratio was greater than one across all zones, suggesting indoor activities as the primary source of PM. In both seasons, the mean indoor and outdoor RCS ranged from 0.02±0.01% to 0.06±0.03%. The mean indoor and outdoor 24 h RCS concentrations in both seasons were below the California Office of Environmental Health Hazard Assessment (OEHHA) defined 24 h ambient exposure threshold of 3 µg/m3. Conclusion: The study found that PM4 concentration was directly proportional to distance from the gold mine tailings. Using RCS as a signature chemical, we found a similar chemical composition in all samples collected in winter and dry season at varied distances. It is concluded that the gold mine tailings are the significant source of PM4 emissions. Therefore, further dust control measures needs to be implemented at the gold mine tailings.

Occupational Exposure to Silica Dust and Silicosis Risk in Chinese Noncoal Mines: Qualitative and Quantitative Risk Assessment.

Despite increasing awareness, silica dust-induced silicosis still contributes to the huge disease burden in China. Worryingly, recent silica dust exposure levels and silicosis risk in Chinese noncoal mines remain unclear. We aimed to determine recent silica dust exposure levels and assess the risk of silicosis in Chinese noncoal mines. Between May and December 2020, we conducted a retrospective cohort study on 3 noncoal mines and 1 public hospital to establish, using multivariable Cox regression analyses, prediction formulas of the silicosis cumulative hazard ratio (H) and incidence (I) and a cross-sectional study on 155 noncoal mines in 10 Chinese provinces to determine the prevalence of silica dust exposure (PDE), free silica content, and total dust and respirable dust concentrations. The qualitative risk of silicosis was assessed using the International Mining and Metals Commission's risk-rating table and the occupational hazard risk index; the quantitative risk was assessed using prediction formulas. Kaplan-Meier survival analysis revealed significant differences in the silicosis probability between silica dust-exposed male and female miners (log-rank test χ21=7.52, P=.01). A total of 126 noncoal mines, with 29,835 miners and 4623 dust samples, were included; 13,037 (43.7%) miners were exposed to silica dust, of which 12,952 (99.3%) were male. The median PDE, free silica content, total dust concentration, and respirable dust concentration were 61.6%, 27.6%, 1.30 mg/m3, and 0.58 mg/m3, respectively, indicating that miners in nonmetal, nonferrous metal, small, and open-pit mines suffer high-level exposure to silica dust. Comprehensive qualitative risk assessment showed noncoal miners had a medium risk of silicosis, and the risks caused by total silica dust and respirable silica dust exposure were high and medium, respectively. When predicting H and I over the next 10, 20, and 30 years, we assumed that the miner gender was male. Under exposure to current total silica dust concentrations, median I10, I20, and I30 would be 6.8%, 25.1%, and 49.9%, respectively. Under exposure to current respirable silica dust concentrations, median I10, I20, and I30 would be 6.8%, 27.7%, and 57.4%, respectively. These findings showed that miners in nonmetal, nonferrous metal, small, and open-pit mines have a higher I and higher qualitative silicosis risk. Chinese noncoal miners, especially those in nonmetal, nonferrous metal, small, and open-pit mines, still suffer high-level exposure to silica dust and a medium-level risk of silicosis. Data of both total silica dust and respirable silica dust are vital for occupational health risk assessment in order to devise effective control measures to reduce noncoal mine silica dust levels, improve miners' working environment, and reduce the risk of silicosis.

Trends in Exposure to Respirable Dust and Respirable Crystalline Silica Among Lithium Mine Workers in Western Australia

BackgroundExposure to respirable dust (RES) and respirable crystalline silica (RCS) is common in mining operations and is associated with health effects such as pneumoconiosis, chronic obstructive pulmonary disease (COPD), interstitial pulmonary fibrosis, silicosis, lung cancer, and renal disease. MethodsThis study used industry occupational exposure data for respirable dust from two surface lithium mines in Western Australia for the period between 2017 and 2023. A total of 1122 samples were collected in workgroups across four departments - administration and support, mining, crushing and processing, and maintenance. ResultsThe study found that the overall RES concentration did not exceed the exposure standard. However, Crusher Dry/Wet Plant Personnel (0.558 mg/m3) and Workshop Boilermakers (0.842 mg/m3) recorded elevated exposure to RES. The highest mean exposures for RCS over the seven-year study period were measured for Management Administration & Technical (0.068 mg/m3), followed by Crusher Dry/Wet Plant Personnel (0.042 mg/m3), exceeding the ES. Maximum results for both RES (15.00 mg/m3) and RCS (2.50 mg/m3) indicated exceedances. ConclusionThe study demonstrated a decline in exposure to RES over the seven years of study from 0.472 mg/m3 to 0.151 mg/m3, with a slight increase in 2019 and 2022. A decline in the concentration of RCS was observed between 2019 -2021, followed by an increase after 2021. The mean concentration of RCS exceeded the exposure standard in 2023. Based on the study results and the established adverse health effects associated with exposure to silica, various control measuresto protect workers from RCS exposure should be considered.

The impact of respirable dust exposure on lung function parameters of motorcycle taxi drivers in Bangkok and adjacent provinces, Thailand

AbstractThe motorcycle taxi drivers of Bangkok and adjacent provinces in Thailand may have been heavily exposed to ambient air pollution and the impact of this on their lungs has been neither documented nor studied. In this study, we recruited a total of 343 motorcycle taxi drivers in Bangkok and adjacent provinces in Thailand and their lung function parameters were analyzed using spirometry in May and June 2022. Of these, 153 participants were selected and their exposure to respirable dust during working was measured by personal air sampling. Respirable dust concentrations collected with personal air sampling suggested that motorcycle taxi drivers working at workstations where they were exposed to respirable dust at high concentrations tended to have a low percent predicted FEV1. Twelve% and 7.3% of motorcycle taxi drivers recruited in this study had the symptoms of chronic bronchitis and acute bronchitis, respectively. These results suggested that some motorcycle taxi drivers around Bangkok and adjacent provinces had a high risk of occupational exposure to ambient air pollution. The government needs to establish a medical check-up system for motorcycle taxi drivers to monitor their health status.

CFD MODELLING OF THE DUST AND AIR VELOCITY BEHAVIOUR AT AN UNDERGROUND COAL MINE ROADWAY

Dust pollution for ventilation systems is a big problem for mine workers in underground coal mines. The respirable dust concentration is important to the physical and spiritual health of miners. It is hazardous up to 2 mg/m3in the air in underground coal galleries. In the present work, the airflow velocity and dust concentration values were measured at Çay 1-Kartiye roadway in Kozlu, Zonguldak. The goal of this research is modelling to the dust concentration and airflow velocity values by the computational fluid dynamics (CFD) method. An airflow and dust fluid and solid model was done using the Eularian-Granular multiphase method with the k-epsilon two-equation model. The results showed that dust concentration values were too low and fixed. The error percentage of airflow velocity values changed between 5% and 17%. Thus, this roadway is safe for coal dust explorations.

181 Evaluation of respirable dust and respirable crystalline silica area concentrations in a clay brick factory using a field-based approach

181 Evaluation of respirable dust and respirable crystalline silica area concentrations in a clay brick factory using a field-based approach

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&amp;lt;200C (p&amp;lt;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 (&amp;lt;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 &amp;gt; 0.580 and R&amp;gt;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.