Respirable Dust Measurements Research Articles

A temporal evaluation of respirable crystalline silica exposure for construction tasks.

Personal air monitoring using a TSI SidePak AM520 personal aerosol monitor was performed on a northern Colorado construction site during five tasks from the OSHA Table 1: Specified Exposure Control Methods When Working With Materials Containing Crystalline Silica to estimate silica dust concentrations in real time. Photometric measurements were modified using a gravimetric correction factor and a % respirable crystalline silica adjustment. Each task was sampled once; sample time ranged from 14 min to 40 min, with a mean sample time of 27 min. The mean silica dust concentration estimates (μg/m3) (standard deviation [SD]) for the five tasks computed from the TSI SidePak AM520 respirable dust measurements were core drilling 12 μg/m3 [2.46], grinding 918 μg/m3 [1134.08], cutting with a walk-behind saw 36 μg/m3 [79.67], jackhammering 27 μg/m3 [23.24], and dowel drilling 66 μg/m3 [77.65]. Silica exposure estimates from real-time monitoring can be used to identify exposures that may be related to inadequate controls or worker behaviors that contribute to peak exposures. Respirable crystalline silica exposure estimates presented here are likely not generalizable to other construction sites or tasks.

Silicosis, tuberculosis and silica exposure among artisanal and small-scale miners: A systematic review and modelling paper.

An estimated 44 million artisanal and small-scale miners (ASM), largely based in developing economies, face significant occupational risks for respiratory diseases which have not been reviewed. We therefore aimed to review studies that describe silicosis and tuberculosis prevalence and respirable crystalline silica (RCS) exposures among ASM and use background evidence to better understand the relationship between exposures and disease outcomes. We searched PubMed, Web of Science, Scopus and Embase for studies published before the 24th March 2023. Our primary outcome of interest was silicosis or tuberculosis among ASM. Secondary outcomes included measurements of respirable dust or silica, spirometry and prevalence of respiratory symptoms. A systematic review and narrative synthesis was performed and risk of bias assessed using the Joanna Briggs Prevalence Critical Appraisal Tool. Logistic and Poisson regression models with predefined parameters were used to estimate silicosis prevalence and tuberculosis incidence at different distributions of cumulative silica exposure. We identified 18 eligible studies that included 29,562 miners from 13 distinct populations in 10 countries. Silicosis prevalence ranged from 11 to 37%, despite four of five studies reporting an average median duration of mining of <6 years. Tuberculosis prevalence was high; microbiologically confirmed disease ranged from 1.8 to 6.1% and clinical disease 3.0 to 17%. Average RCS intensity was very high (range 0.19-89.5 mg/m3) and respiratory symptoms were common. Our modelling demonstrated decreases in cumulative RCS are associated with reductions in silicosis and tuberculosis, with greater reductions at higher mean exposures. Despite potential selection and measurement bias, prevalence of silicosis and tuberculosis were high in the studies identified in this review. Our modelling demonstrated the greatest respiratory health benefits of reducing RCS are in those with highest exposures. ASM face a high occupational respiratory disease burden which can be reduced by low-cost and effective reductions in RCS.

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.

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.

Influence of Saw Chain Type and Wood Species on the Mass Concentration of Airborne Wood Dust during Cross-Cutting

Chainsaw operation is associated with several hazards, including exposure to wood dust, a risk factor which requires serious attention due to health impacts such as respiratory disease. This study aims to investigate the effect of saw chain type and wood species on the mass concentration of airborne wood dust during chainsaw cross-cutting operations. Real-time inhalable and respirable dust measurements in the breathing zone of the chainsaw operator were carried out using a desktop aerosol monitor. Three types of cutter shape (semi chisel, full chisel, and chamfer chisel) and four types of wood species (oak, beech, spruce, and fir) were used in the experiments. The split-plot ANOVA results showed that both respirable and inhalable mass concentrations of wood dust were affected exclusively by wood species. No statistically significant differences were found among particular levels of cutter shape. The highest average mass concentrations of airborne dust were generated by the combination of oak wood and a full chisel cutter.

Study on neural network algorithm for detecting respirable dust in photoacoustic cavity

The traditional photoacoustic cavity has the advantages of simple structure, low cost, and easy integration with optical cavity technology, so it has significant advantages in the measurement of the optical characteristics of respirable dust. In order to meet the demand of high-precision respirable dust measurements in practical applications, it is necessary to improve the measurement accuracy of respirable dust by traditional photoacoustic spectroscopy technology. Therefore, the structure size of the photoacoustic cavity was determined by theoretical and simulation analysis. A system for measuring respirable dust by photoacoustic spectroscopy was designed, which was applied to the atmospheric respirable dust detection simultaneously with the cavity ring-down spectroscopy system. The results showed that the correlation between the two systems was poor. Therefore, the three-layer back propagation neural network algorithm was used to correct the photoacoustic response values, and the measured value of the cavity ring-down spectroscopy system was used as the reference truth value. The calibration results showed that the output value of the neural network model was in good agreement with the reference true value: the slope was above 0.96. The results showed that the neural network algorithm could effectively improve the measurement accuracy of the photoacoustic spectroscopy system to respirable dust, improve the linearity, and reduce the detection error.

Respirable Coal Mine Dust: A Review of Respiratory Deposition, Regulations, and Characterization

In the late 1990s, despite years of efforts to understand and reduce coal worker’s pneumoconiosis (CWP) prevalence from more than 30% in 1970 to less than 4.2%, the level of occurrence among the US coal miners increased unexpectedly. The recent resurgence of lung diseases has raised concerns in the scientific and regulatory communities. In 2014, the United States Mine Safety and Health Administration (MSHA) issued a new dust rule changing the respirable coal mine dust (RCMD) exposure limits, measurement technology, and sampling protocol. The analysis for probable causes for the substantial increase in the CWP incidence rate is rather complicated. This paper aims to conduct a review of RCMD respiratory deposition, health effects, monitoring, regulations, and particle characteristics. The primary sources of RCMD along with the health risks from potential exposure are highlighted, and the current RCMD exposure regulations of the major coal producer countries are compared. A summary of RCMD characterization studies from 1972 to the present is provided. A review of the literature revealed that numerous factors, including geological and mining parameters, advancements in mining practices, particle characteristics, and monitoring approaches are considered to contribute to the recent resurgence of RCMD lung diseases. However, the root causes of the problem are still unknown. The effectiveness of the new dust rules in the United States will probably take years to be correctly assessed. Therefore, future research is needed to understand the relationship between RCMD particle characteristics and lung deposition, and the efficacy of current monitoring practices to measure the true dose of RCMD exposure.

Lung Function Impairment and Workplace Control Measures among Marble Stone Carvers in Sa-Kyin Village, Madayar Township, Myanmar

Introduction: Marble rocks, composed of dust containing calcium carbonate and silica particles, predispose to a higher prevalence of occupational lung diseases. This study aimed to assess workplace control measures and lung function impairment among marble stone carvers.&#x0D; Methods: A cross-sectional descriptive study was conducted among 120 marble stone carvers in Sa-Kyin Village, Madayar Township in May 2019. Information about existing control measures in the workplace was assessed using a pre-tested structured questionnaire and participants’ lung function using spirometry. Respirable dust measurements in twelve randomly selected workers were performed by personal air sampling pumps.&#x0D; Results: It was found that 9.2% of marble stone carvers used disposable or cloth masks throughout the working time, but no one was found using appropriate devices like respirators. No one reported about regular medical checkup and provision of health education at the workplaces. Spirometry testing showed 55.8% had lung function impairment. Concentrations of respirable dust ranged from 7.19 to 10.13 mg/m3, significantly higher than the recommended Threshold Limit Value (3 mg/m3). In multivariable logistic regression analysis, development of lung function impairment was associated with age [adjusted Odds Ratio (aOR) = 2.84; 95% CI = 1.02,7.91] and use of face mask (aOR = 0.11; 95% CI = 0.01,0.91).&#x0D; Conclusion: The working environment was found dusty, and a significant proportion of workers had lung function impairment. It is essential to adopt proper dust control measures in stone carving workplaces. Preventive measures like medical surveillance and health education program are vital to reduce the burdens from occupational lung diseases.

Exposure assessment to inhalable and respirable dust in the post - earthquake construction sites in the city of l'Aquila.

ObjectivesFollowing an earthquake that occurred in middle Italy in 2009, the involved territory hosted in 10 years thousands of construction sites. The aim of this study is to assess inhalable, respirable, and respirable crystalline silica exposure of the construction workers involved in the rebuilding activities.MethodsSix construction companies joined the study and hosted the air sampling activities. We identified four work tasks: bricklayer and similar; scaffolder and carpenter; manual demolition; other tasks. We reported 8‐h time‐weighted concentrations.ResultsThe “All tasks” geometric mean concentration of inhalable dust was 4.73 mg/m3 and the higher, TLV exceeding exposure was observed for “Manual demolition workers” (13.92 mg/m3, GM). The “All tasks” geometric mean concentration of respirable dust was 0.25 mg/m3 and no TLV‐exceeding exposure (geometric mean values) was observed among the work‐related groups. About the respirable crystalline silica dust exposure, the “All tasks” average concentration was 0.004 mg/m3. No TLV‐exceeding exposure was observed among the whole data sample.ConclusionsThe comparison of the results shows that manual demolition workers are exposed to high levels of inhalable dust, exceeding the TLV‐TWA (Threshold Limit Values‐Time Weighted Average) limit of 10 mg/m3. About the respirable dust concentration, none of the analyzed work task dust concentrations exceeded the TLV‐TWA limit of 3 mg/m3 (geometric mean values). Measurements of respirable crystalline silica dust have shown levels below the threshold limit value of 0.025 mg/m3. Our findings overall match with the available scientific data.

Selection of operational parameters for a smart spraying system to control airborne PM10 and PM2.5 dusts in underground coal mines

Airborne dust in underground hard coal mines is an ongoing explosion and respiratory health hazard. The latest design solution for controlling dusts, the smart spraying system, is described. From the results of stand tests, the main factors determining the efficiency of the new device are: 1) the integrated real-time acquisition of dust particle size and concentration data, determined using a new optical dust meter; 2) the fractional distribution of water droplets; and 3) the selection of droplet size to capture PM10 and PM2.5. The latter two factors are automatically controlled, based on dust measurements, by varying the pressure of water and compressed air supplied to the sprayer nozzles. The effects of varying these parameters and the results of stand tests are presented. The spraying device was tested for the effectiveness of PM2.5 dust and PM10 dust reduction in underground conditions in the KWK Pniówek mine. The tests were based on the following Polish Standards: PN-91/Z-04030/05 and PN91/Z-04030/06, which define the methodology for measurements of inhalable and respirable dust at workplaces using the filtration-weighing method to determine the concentration of inhalable and respirable dust with the spraying system on and off. The results showed that the assumed objective, i.e. development of a dust control device that would reduce PM2.5 dust (by min. 25 %) and PM10 dust (by min. 20 %) more effectively than the currently used solutions, was achieved in the project. At the same time, the device, due to application of dust sensor, continuously adjusts the parameters of spraying streams to the dust concentration level, optimizing the consumption of water and compressed air. Similar results in reduction of PM10 and PM2.5 dust, with an average effectiveness of over 60 % is the undoubted advantage of the device.

The Analysis of c-silica Dust Content in Respirable Dust in the Ceramic Industry

Introduction: Exposure to hazards in the work environment in the ceramic industry includes silica dust and heat temperatures. The purpose of this research was to analyze the respirable dust and c-silica dust, in addition to calculate c-silica dust in respirated dust. In addition, an evaluation of the results of dust measurements was also carried out by comparing it to the threshold value. Method: This was a descriptive study by testing samples of respirable dust and c-silica dust in the work place. The research was conducted at one of the ceramic industries in East Java. Data collection was carried out on all workers in the production division of 39 peoples. The measurement method for respirable dust analysis used the gravimetric method based on NIOSH method (NMAM 0600, 1998), while the analysis of c-silica dust used XRD equipment in accordance with the NIOSH method (NMAM 7500, 2003). Results: The results of the measurement of respirable dust in 39 respondents obtained a range of values of 0.019 - 0.0563 mg/m3 with an average of 0.19 mg/m3, while for c-silica dust, the results were at the range of 0.0020 - 0.3129 mg/m3 with an average of 0.07 mg/m3. The percentage of c-silica dust content in the ceramics industry in residential dust is different by 5 - 74.3% with the average of 34.89%. Conclusion: Evaluation of the results of measurement of respirable dust found that all samples were below the threshold value, while for c-silica dust, there were 27 samples with values above the threshold. On the average, there is 34.89% level of c-silica in respirable dust in the ceramic industry.Keywords: ceramic industry, c-silica, respirable dust

Effect of welding fumes on the cardiovascular system: a six-year longitudinal study.

Objective:This study investigated whether low-to-moderate exposure to welding fumes is associated with adverse effects on the cardiovascular system.Methods:To test this, we performed a longitudinal analysis of 78 mild steel welders and 96 controls; these subjects were examined twice, six years apart (ie, timepoints 1 and 2). All subjects (male and non-smoking at recruitment) completed questionnaires describing their health, work history, and lifestyle. We measured their blood pressure, endothelial function (by EndoPAT), and risk markers for cardiovascular disease [low-density lioprotein (LDL), homocysteine, C-reactive protein]. Exposure to welding fumes was assessed from the responses to questionnaires and measurements of respirable dust in their breathing zones adjusted for use of respiratory protection equipment. Linear mixed-effect regression models were used for the longitudinal analysis.Results:Median respirable dust concentrations, adjusted for respirable protection, of the welders were 0.7 (5–95 percentile range 0.2–4.2) and 0.5 (0.1–1.9) mg/m3 at timepoints 1 and 2, respectively. Over the six-year period, welders showed a statistically significant increase in systolic [5.11 mm Hg, 95% confidence interval (CI) 1.92–8.31] and diastolic (3.12 mm Hg, 95% CI 0.74–5.5) blood pressure compared with controls (multi-variable adjusted mixed effect models). Diastolic blood pressure increased non-significantly by 0.22 mm Hg (95% CI -0.02–0.45) with every additional year of welding work. No consistent significant associations were found between exposure and endothelial function, LDL, homocysteine, or C-reactive protein.Conclusion:Exposure to welding fumes at low-to-moderate levels is associated with increased blood pressure, suggesting that reducing the occupational exposure limit (2.5 mg/m3 for inorganic respirable dust in Sweden) is needed to protect cardiovascular health of workers.

Analysis of Historical Worker Exposures to Respirable Dust from Talc Mining and Milling Operations in Vermont.

Talc is mined and milled throughout the world for use in a variety of industrial and consumer products. Although prior studies have evaluated workplace exposures or health effects from talc operations, the primary emphasis of these investigations has been on certain mineral contaminants (e.g. crystalline silica and asbestos) rather than talc itself. The purpose of this analysis is to evaluate historical worker exposures to respirable dust (as a measure of talc exposures) in the Vermont talc mines and mills, which involved a relatively pure form of talc (i.e. no asbestos and <0.25% or <1% crystalline silica). Respirable dust sampling data collected for workers in the Vermont mines and mills, which have not been previously published, were obtained from both mining company records and Mine Safety and Health Administration (MSHA) inspections. Because of differences in sampling design, the company and MSHA data were analyzed and reported separately. Overall, nearly 700 respirable dust samples collected for 44 job categories at 7 site locations over an approximate 30-year period were analyzed. Average respirable dust concentrations were found to exceed occupational exposure limits (OELs) in the United States and other countries for several job categories and site locations. Regardless of data source, the highest observed exposures were for mining jobs involving the operation of heavy equipment to break up, move, or load raw ore from the mines and milling or shipping jobs involving the crushing of raw ore, cleaning and drying of processed talc, and bagging and packaging of the final talc product. When analyzing the company data, the arithmetic mean respirable dust concentration was 2.73 mg m-3 for Muckerman at Hammondsville Mine, 3.18 mg m-3 for dosco operator at Ludlow mines, 1.35 mg m-3 for crusher operator at Gassetts Mill, 2.4 mg m-3 for palletizer at West Windsor Mill, and 2.68 mg m-3 for bagging operator at Columbia Shipping Center. When analyzing the MSHA data, the arithmetic mean respirable dust concentration was 3.5 mg m-3 for kiln/dryer operator at Hammondsville Mine, 1.27 mg m-3 for driller at Ludlow mines, 3.69 mg m-3 for ball mill operator at Columbia mill, 3.02 mg m-3 for flotation operator at West Windsor Mill, and 3.24 mg m-3 for bagging operator at Columbia Shipping Center. Worker exposures were found to decline over time for many, but not all, jobs. Our findings highlight potential high-risk jobs that might benefit from additional exposure control strategies at current or future talc manufacturing sites. The respirable dust measurements summarized here may also be used to reconstruct historical worker exposures at the Vermont sites or aid in subsequent epidemiology studies of this cohort focused on malignant or non-malignant respiratory disease.

Temporal trends in respirable dust and respirable quartz concentrations within the European industrial minerals sector over a 15-year period (2002–2016)

ObjectivesSince 2000 the European Industrial Minerals Association’s Dust Monitoring Programme (IMA-DMP) has systematically collected respirable dust and respirable quartz measurements from 35 companies producing industrial minerals. The IMA-DMP initiative allowed...

Quartz Dust Exposure Affects NLRP3 Inflammasome Activation and Plasma Levels of IL-18 and IL-1Ra in Iron Foundry Workers.

Purpose To study the association between inhalation of particulate matter or quartz in Swedish iron foundries and the effects on NLRP3 inflammasome activation. Methods Particle exposure measurements were performed during an eight-hour work day for 85 foundry workers at three Swedish iron foundries. Personal sampling was used for measurement of respirable quartz and dust and stationary measurements to obtain exposure measurements for inhalable dust and PM10. The NLRP3 inflammasome markers, interleukin- (IL-) 1β and IL-18, and inhibitors IL-1 receptor antagonist (IL-1Ra) and IL-18 binding protein (IL-18BP) were measured in plasma. Inflammasome activation was measured by caspase-1 enzymatic activity in monocytes in whole blood by flow cytometry, and expression of inflammasome-related genes was quantified using real-time PCR. Multiple linear regression analysis was used to investigate associations between PM exposures and inflammatory markers. Sex, age, smoking, current infection, BMI, and single nucleotide polymorphism in the inflammasome regulating genes CARD8 (C10X) and NLRP3 (Q705K) were included as covariates. Results The average exposure levels of respirable dust and quartz were 0.85 and 0.052 mg/m3, respectively. A significant exposure-response was found for respirable dust and IL-18 and for inhalable dust and IL-1Ra. Whole blood, drawn from study participants, was stimulated ex vivo with inflammasome priming stimuli LPS or Pam3CSK4, resulting in a 47% and 49% increase in caspase-1 enzymatic activity in monocytes. This increase in caspase-1 activity was significantly attenuated in the higher exposure groups for most PM exposure measures. Conclusions The results indicate that exposure levels of PM in the iron foundry environment can affect the NLRP3 inflammasome and systemic inflammation.

Mild steel welding is associated with alterations in circulating levels of cancer-related proteins

Welding fumes were recently classified as carcinogenic to humans and worldwide millions work as welders or perform welding operations. The purpose of this study was to identify new biomarkers of welding-induced carcinogenesis. We evaluated a panel of 91 putative cancer-related proteins in serum in a cohort of welders working with mild steel (n = 77) and controls (n = 94) from southern Sweden sampled on two occasions 6-year apart using a longitudinal analysis (linear mixed models). The significant results from the longitudinal analysis were tested for reproducibility in welders (n = 88) and controls (n = 69) sampled once during the same sampling period as timepoint 1 or timepoint 2 (linear regression models), i.e., in a cross-sectional setting. The models were adjusted for age, body-mass index, and use of snus. All study participants were non-smokers at recruitment. Exposure to welding fumes was assessed using questionnaires and respirable dust measurement in the breathing zone that was adjusted for personal respiratory protection equipment. The median respirable dust in welders was 0.7 (0.2–4.2) and 0.5 (0.1–1.9) mg/m3 at the first and second timepoints, respectively. We identified 14 cancer-related proteins that were differentially expressed in welders versus controls in the longitudinal analysis, out of which three were also differentially expressed in the cross-sectional analysis (cross-sectional group). Namely, syndecan 1 (SDC1), folate receptor 1 (FOLR1), and secreted protein acidic and cysteine rich (SPARC) were downregulated, in welders compared with controls. In addition, FOLR1 was negatively associated with years welding. Disease and function analysis indicated that the top proteins are related to lung cancer as well as cell invasion and migration. Our study indicates that moderate exposure to welding fumes is associated with changes in circulating levels of putative cancer-related proteins, out of which FOLR1 showed a clear dose–response relationship. It is, however, unclear to which extent these changes are adaptive or potential early biomarkers of cancer.

Occupational Exposures in an Equestrian Centre to Respirable Dust and Respirable Crystalline Silica.

Sand-based products are regularly used as footing material on indoor equestrian arenas, creating a potential occupational exposure risk for respirable crystalline silica (RCS) for equestrian workers training and exercising horses in these environments. The objective of this study was to evaluate an equestrian worker’s personal RCS and respirable dust (RD) exposure. Sixteen personal full-shift RD measurements were collected from an equestrian worker and analysed for RD, quartz and cristobalite. Geometric mean exposures of 0.12 mg m−3 and 0.02 mg m−3 were calculated for RD and RCS concentrations, respectively. RCS exposures of between 0.01 to 0.09 mg m−3 were measured on days when the indoor arena surface was not watered, compared to lower exposures (<LOD-0.03 mg m−3) on days when the indoor arena was watered (p < 0.01); however, manual watering is time intensive and less likely to be implemented in practice. This small-scale study provides new data on RCS and RD exposures among equestrian workers. RCS exposures are within the range considered to be associated with increased risk for lung cancer. The use of dust control solutions such as water suppression should be promoted for equestrian work in horse riding arenas. Equestrian workers need to receive occupational health training on the health risks associated with RCS exposure.

A field evaluation of a single sampler for respirable and inhalable indium and dust measurements at an indium-tin oxide manufacturing facility

Indium-tin oxide production has increased greatly in the last 20 years subsequent to increased global demand for touch screens and photovoltaics. Previous studies used measurements of indium in blood as an indicator of indium exposure and observed associations with adverse respiratory outcomes. However, correlations between measurements of blood indium and airborne respirable indium are inconsistent, in part because of the long half-life of indium in blood, but also because respirable indium measurements do not incorporate inhalable indium that can contribute to the observed biological burden. Information is lacking on relationships between respirable and inhalable indium exposure, which have implications for biological indicators like blood indium. The dual IOM sampler includes the foam disc insert and can simultaneously collect respirable and inhalable aerosol. Here, the field performance of the dual IOM sampler was evaluated by comparing performance with the respirable cyclone and traditional IOM for respirable and inhalable indium and dust exposure, respectively. Side-by-side area air samples were collected throughout an indium-tin oxide manufacturing facility. Cascade impactors were used to determine particle size distribution. Several statistical methods were used to evaluate the agreement between the pairs of samplers including calculating the concordance correlation coefficient and its accuracy and precision components. One-way ANOVA was used to evaluate the effect of dust concentration on sampler differences. Respirable indium measurements showed better agreement (concordance correlation coefficient: 0.932) compared to respirable dust measurements (concordance correlation coefficient: 0.777) with significant differences observed in respirable dust measurements. The dual IOM measurements had high agreement with the traditional IOM for inhalable indium (concordance correlation coefficient: 0.997) but lower agreement for inhalable dust (concordance correlation coefficient: 0.886 and accuracy: 0.896) with a significantly large mean bias (-146.9 µg/m3). Dust concentration significantly affected sampler measurements of inhalable dust and inhalable indium. Results from this study suggest that the dual IOM is a useful single sampler for simultaneous measurements of occupational exposure to respirable and inhalable indium.

PM2.5 or respirable dust measurement and their use for assessment of dust separators

Abstract Different dust fractions, e.g. PM2.5 for environment- and PM4 for workplace limits, are in use to describe the respirable dust amount. International and national standards describe thereby different cut-off limits, measurement methods and calculation procedures. Especially continuous measuring devices that commonly work with optical or electronical auxiliary aids, cannot measure the same absolute respirable dust fraction, because of possible measuring errors. In order to solve this problem, laborious and costly procedures are necessary to have valid results merely for the calibrated dust. If not the measurement of a PM2.5 value for controlling standard dust limits, which are gravimetric defined, is the priority and regarding only the assessment and optimization of dust separators concerning to their respirable dust separation, a simplest possible measurement technique would be sufficient. In this paper, a method for the assessment of the respirable dust separation efficiency using solely an optical particle counter is presented. In addition, the application of this method is shown on the optimization of a special wet-scrubber and on the classification of cleanable dust filter media regarding their respirable dust separation efficiency and their energy consumption.

Respirable dust measured downwind during rock dust application.

The Pittsburgh Mining Research Division of the U.S. National Institute for Occupational Safety and Health (NIOSH) conducted underground evaluations in an attempt to quantify respirable rock dust generation when using untreated rock dust and rock dust treated with an anticaking additive. Using personal dust monitors, these evaluations measured respirable rock dust levels arising from a flinger-type application of rock dust on rib and roof surfaces. Rock dust with a majority of the respirable component removed was also applied in NIOSH's Bruceton Experimental Mine using a bantam duster. The respirable dust measurements obtained downwind from both of these tests are presented and discussed. This testing did not measure miners' exposure to respirable coal mine dust under acceptable mining practices, but indicates the need for effective continuous administrative controls to be exercised when rock dusting to minimize the measured amount of rock dust in the sampling device.