Respirable Dust Samples Research Articles

Impact of construction activities on the air quality of Agra city, Uttar Pradesh, India

The current research work was carried out to comprehensively assessed the impact of construction activities on the air quality. Seven sites were chosen along the metro line construction in Agra, Uttar Pradesh, India, to meet the study's goals. The monitoring was performed for 24 hours at each site using the respirable dust sampler (RDS) with a gaseous sampling attachment. The raw data was processed to calculate the Air Quality Index (AQI). The data obtained indicate that all the examined sites had PM10 (particulate matter having the diameter less than or equal to 10 micron) values above the National Ambient Air Quality Standards (NAAQ) values of 100 µg/m3, while SS-05 and SS-06 had PM2.5 (particulate matter having the diameter less than or equal to 2.5 micron) values above the NAAQ values of 60 µg/m3. Values of CO, SO2, and NO2 were discovered to be lower than the NAAQ standard limits. Because PM10's sub index (Si) was found to be the greatest across all locations, it was determined to be the criterion pollutant among all the metrics. Based on the AQI value, the research area's overall air quality was determined to be moderately polluted. At every location, a variety of management techniques, including mist guns, water spraying, and planting, are regularly used to reduce air pollution. Effective implementation of applied air pollution control measures is required to make the air clean and safe for breathing.

Preliminary Study on Mercury and Lead in the Ambient Air of Metro Manila, the Philippines

Despite being acknowledged as an air pollutant, heavy metal contaminants in the atmosphere are not yet well studied in the Philippines. This study aims to assess the particulate matter, as well as mercury and lead concentration, in Metro Manila's ambient atmosphere. A one-hour sampling period was used to collect data at seven sampling stations using a respirable dust sampler with a flow rate of 1.4 m3/min. The mercury concentration was determined using cold vapor atomic absorption spectroscopy, whereas lead concentrations were measured using flame atomic absorption spectroscopy. Taguig had the highest level of total suspended particulates (TSP) at 524.07 μg/NCM, followed by Caloocan (459.92 μg/NCM) and Quezon City (434.50 μg/ NCM). Parañaque reported moderate particulate levels – recorded at 298.95, 291.69, and 347.36 μg/NCM, respectively. Valenzuela had the lowest TSP level at 263.85 μg/NCM. Results show that mercury concentrations were highest in the City of Manila with 0.09 μg/m3, followed by Valenzuela City with 0.009 μg/m3, against the lowest concentration in Taguig City and Quezon City with 0.001 μg/m3. However, based on the legal airborne permissible exposure from the Philippine Occupational Safety and Health Standards, the mercury concentration in the seven cities of Metro Manila did not exceed its 0.5 mg/m3 (50 μg/m3) limit. Furthermore, results revealed that atmospheric lead concentration in Metro Manila existed only in trace amounts (≤ limit of detection). The high concentration of mercury in the City of Manila could be attributed to its high population density combined with massive industrial, commercial, and transport activities. Monitoring the concentration of heavy metals in the atmosphere is critical for the development of effective strategies for reducing the negative impacts of these global pollutants.

Particulate matter concentrations around natural gas-fired power plants and their associated health impact assessment

The quantification and prediction of particulate matter (PM) concentrations in the air are essential due to their negative impacts on human health and the environment. This study quantified PM concentrations and associated health effects at four natural gas-based power plants in Bangladesh. The measurement of PM2.5 and PM10 using the respirable dust samplers APS-113NL and APS-113BL, respectively from the year of 2015 to 2021 revealed that the concentration of both types of particles fluctuated over the years. The highest recorded levels of particles were in 2019, with PM2.5 at 126 µg/m3 and PM10 at 283 µg/m3 and the lowest recorded levels of particles were in 2017, with PM2.5 at 76.3 µg/m3 and PM10 at 203.3 µg/m3. In 2021, PM2.5 and PM10 concentrations were 88.5 and 225 µg/m3, respectively, lower than in the past two years. Statistical modeling assessed atmospheric contaminants analyzed time series data, and projected air quality. ARIMA, ETS, and ANN modeling methods have been used to predict the monthly average of PM2.5 and PM10 concentrations. RMSE, MAPE, MASE, and MAE have been utilized for model orders, time series analysis, and forecasting validation. There is a significant variation between the forecasting models and forecasts for average PM2.5 and PM10 concentrations in natural gas-fired power plants from 2022 to 2024. This study also conducted a face-to-face interview with over 100 employees using a structured questionnaire to assess the health effects they are facing due to poor air quality in the power generation complex and found that 2 and 13 % of employees had respiratory and skin issues, respectively. Nonetheless, regular health checks, air filtration, and renewable energy consumption may benefit residents and the environment.

Characterization of Respirable Coal Mine Dust Recovered from Fibrous Polyvinyl Chloride Filters by Scanning Electron Microscopy

The characterization of respirable dust on the basis of constituent fractions and particle sizes is increasingly of concern for evaluating exposure hazards. For high-resolution particle analysis, scanning electron microscopy with energy dispersive X-ray (SEM-EDX) can be an effective tool. However, it requires particles to be deposited on a smooth, uniform substrate such as a polycarbonate (PC) filter for optimal results. While direct sampling onto PC is possible, this is not the standard approach in many situations. For example, in coal mines, respirable dust samples have typically been collected onto polyvinyl chloride (PVC) filters because they are intended for gravimetric and/or infrared spectroscopy analysis. Such fibrous substrates are not ideal for SEM-EDX (or other microscopy), but an effective method to recover and redeposit the dust particles could render such samples suitable for the additional analysis. Here, we present a simple method and compare SEM-EDX results for paired samples analyzed directly on PC and following recovery from PVC and redeposition on PC. Both laboratory-generated dust samples (n = 10 pairs) and field samples of respirable coal mine dust (n = 44 pairs) are included in this study. Although some changes in particle size distributions were observed between samples analyzed directly and those that were recovered and redeposited prior to analysis, the results indicate the dust recovery method generally yields a representative sample in terms of mineral constituents. That said, results also highlighted the effects of high particle loading density on individual particle analysis. Considering all sample pairs, those with similar loading density between the directly analyzed and recovered sample tended to exhibit similar mineralogy distributions. This was generally the case for the lab-generated sample pairs, and the Freeman-Halton exact test of independence indicated that the samples in just three (of 10) pairs were in disagreement in terms of their mineralogy distributions. On the other hand, for the field samples, the directly analyzed sample often had higher loading density than the recovered sample; and the Freeman-Halton test showed that 25 (of 44) pairs were in disagreement. However, the effect of possible particle agglomeration on the directly analyzed samples cannot be ruled out—and exploration of this factor was beyond the scope of the current study.

Method for the Analysis of Respirable Airborne Particulates on Filter Using the Mineral Liberation Analyser

In recent years, the Mineral Liberation Analyser (MLA) has played a pivotal role in analysing respirable and inhalable ambient air samples collected on filters from both underground coal and metalliferous mines. Leveraging backscattered electron (BSE) image analysis and X-ray mineral identification, the MLA offers automated quantitative mineral characterization. The escalating prevalence and severity of mine dust lung diseases, particularly among young miners, have reignited interest in comprehensively understanding the dust’s characterization, encompassing mineralogy, particle size, and shape. Merely measuring total respirable dust exposure and its duration based on gravimetrically determined weight is no longer deemed sufficient in addressing the evolving landscape of occupational health challenges in mining environments. Since the publication of previous studies, efforts have been dedicated to refining the Mineral Liberation Analyser (MLA) methodology for respirable dust sampling. This refinement, discussed in detail in this paper, encompasses various enhancements, such as the implementation of data checks to identify carbon contamination, backscattered electron (BSE) drift, and the misclassification of X-ray spectra. Additionally, an examination of sampling efficiency led to the exploration of using smaller samples as an alternative to the time-intensive analysis of entire filters. Furthermore, this paper presents a reanalysis of paired filter sample sets previously reported using the Sarver Group Methodology. These samples are subjected to analysis using the Mineral Liberation Analyser, providing a more detailed illustration of the outputs derived from the updated methodology and compared to previously published MLA data.

Analysis and Assessment of Gaseous Pollutants along High Traffic Roads (NH 948) in Coimbatore City, India

<p>The growing Urbanization, Industrialization, Institutional, and IT sector development contribute to the exponential growth of motorized road transportation increasing the composition of harmful gaseous pollutants in ambient air. So, it is necessary to analyze and quantify the concentration of pollutants such as CO, NOx, SOx, and PM10 (for calculating the Air Quality Index) in ambient air at traffic signal zones in National Highway 948 across Coimbatore city and to model its dispersion using Quantum GIS. Using a Respirable Dust Sampler, the ambient air samples are collected at various locations based on heavy traffic signals zones during the month of December 2022 – March 2023.Quantified data are compared with National Ambient Air Quality Standards (NAAQS) to know about air quality, i.e., Air Quality Index. The dispersion rate in terms of concentration of CO, NOx, and SOx in the sampling locations of National Highway 948 revealed that; In comparison to other sampling months, the mean NOx concentration was higher in December at SL1 (78 µg/m³).The mean concentration value of SOx was high at SL2 (57 µg/m³) in the month of February 2023, and the mean concentration of CO is relatively high at SL1 (1.93 mg/m3) in NH 948.Sampling Locations such as SL1, SL5, SL7, and SL11 fall under the category of Poor compared to other sampling locations because of improper alignment of roadway, Traffic congestion, Liberty, and Violation of Traffic rules, Lack of vehicular maintenance, and End life vehicles. The lack of implementation of environmental regulations contributes to the bad air quality in most Indian cities.</p>

112 Comparing Various Size Fractions Collected Using Dusttrak And Gravimetric Samples

Abstract Occupational exposure concentrations are routinely collected using gravimetric samples. However, gravimetric samples typically require a long sampling time, especially when there are low exposure concentrations. While long sampling time may be appropriate to verify compliance with 8-h occupational limit values (OELs), they cannot address exposure's temporal and spatial heterogeneity or provide information on peak exposures present in the work environment. Real-time light scattering sensors enable the possibility of collecting high-resolution, low-cost measurements, quickly identifying peak and short-term concentrations, linking exposure to emission sources, and better understanding within-day variation. These technologies have become increasingly popular also for occupational monitoring purposes. In this presentation, the results of the dust samples collected for a randomized double-blinded controlled human exposure chamber study are presented. In six groups, 24 healthy volunteers were exposed to two common stone minerals, quartz diorite, and rhomb porphyry, in 4-h exposure sessions. To control the exposure in the chamber, personal gravimetric samples of respirable dust and stationary gravimetric samples of total dust, PM2.5, and respiratory dust were collected. Additionally, stationary real-time samples of total dust, respirable dust, PM10, PM2.5, and PM1 were collected continuously using DustTrak TSI model DRX 8533. Despite the many advantages of the real-time sensors, evaluating compliance with OELs should be done with caution. Except for the PM2.5 fraction, a significant difference was observed between the gravimetric and the DustTrak samples. While the DustTrak overestimated the PM2.5 concentrations, the total dust concatenations were underestimated by a factor of almost two compared to the gravimetric samples.

130 An Exposure Assessment of dust- and Respirable Quartz Levels During Indoor Renovations

Abstract Construction workers are exposed to a complex mix of inorganic dust and other components. Workers doing interior demolition and renovation work are particularly at risk as the work operations can produce large quantities of dust in areas with low ventilation. The aim of this work is to assess the dust- and respirable quartz levels that workers in the construction industry are exposed to. An additional goal with the study is to investigate the inorganic components present in the respirable dust fraction using Rietveld as a multicomponent analysis with XRD. Workers in the construction industry have been carrying personal respirable air samplers during work with concrete and building bricks. Quartz content in respirable air samples is determined by X-ray powder diffraction (XRD) by using the NISOH 7500 method. Gravimetric analysis of 67 respirable dust samples gave a mean of 1.34 mg/m3 (min 0.028 mg/m3 to max 6.0 mg/m3). Initial determination of quartz content by XRD revealed a mean of 0.109 mg/m3 (n=52) respirable quartz, with a minimum, maximum and median of 0.0074 mg/m3, 0.60 mg/m3 and 0.045 mg/m3 respectively. The X-ray diffractograms show a complex mixture of inorganic components. These results show that construction workers may be exposed to levels above the current OEL for respirable quartz. It is therefore important to measure the quartz levels in this industry.

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.

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

Measurement of Airborne Particles and Volatile Organic Compounds Produced During the Heat Treatment Process in Manufacturing Welding Materials

BackgroundThere is little information about the airborne hazardous agents released during the heat treatment when manufacturing a welding material. This study aimed to evaluate the airborne hazardous agents generated at welding material manufacturing sites through area sampling. Methodsconcentration of airborne particles was measured using a scanning mobility particle sizer and optical particle sizer. Total suspended particles (TSP) and respirable dust samples were collected on polyvinyl chloride filters and weighed to measure the mass concentrations. Volatile organic compounds and heavy metals were analyzed using a gas chromatography mass spectrometer and inductively coupled plasma mass spectrometer, respectively. ResultsThe average mass concentration of TSP was 683.1 ± 677.4 μg/m3, with respirable dust accounting for 38.6% of the TSP. The average concentration of the airborne particles less than 10 μm in diameter was 11.2–22.8 × 104 particles/cm3, and the average number of the particles with a diameter of 10–100 nm was approximately 78–86% of the total measured particles (<10 μm). In the case of volatile organic compounds, the heat treatment process concentration was significantly higher (p < 0.05) during combustion than during cooling. The airborne heavy metal concentrations differed depending on the materials used for heat treatment. The content of heavy metals in the airborne particles was approximately 32.6%. ConclusionsNanoparticle exposure increased as the number of particles in the air around the heat treatment process increases, and the ratio of heavy metals in dust generated after the heat treatment process is high, which may adversely affect workers' health.

Breathing plastics in Metro Manila, Philippines: presence of suspended atmospheric microplastics in ambient air.

Microplastics (< 5mm) have lately been identified in the atmosphere of urban, suburban, and even distant places far from plastic particle areas, suggesting the possibility of long-distance atmospheric transport of microplastics. However, the occurrence, fate, transmission, and effects of these suspended atmospheric microplastics (SAMPs) are all currently unknown in the Philippines. This study investigated the presence of suspected microplastic in the atmosphere of sixteen cities and one municipality of Metro Manila, Philippines. Sampling was conducted using a respirable dust sampler mounted with a Whatman GF/C filter paper at an intake flow rate of 1.4 L/min with Whatman GF/C filter paper. Results reveal that all seventeen sampling areas have the presence of SAMPs. A total of 155 SAMPs were found and confirmed in Metro Manila, with the highest concentration in Muntinlupa City and Mandaluyong City (0.023 SAMP/NCM). Fourteen SAMP types were identified across the sampling areas, ⁓74% with polyester. This study is the first record of the presence of microplastics suspended in the ambient air in the Philippines. It is estimated that an adult person in Metro Manila has the potential to inhale (5-8 per minute, normal minute ventilation) about 1 SAMP if exposed for about 99.0 to 132h. Further studies should be done to evaluate the fate and health effects of these SAMPs in Metro Manila's setting.

Source characterization of PM10 using CMB receptor modeling for the western industrial area of India

Introduction: Receptor models use the chemical characterisation of particulate matter to distinguish the source and analyse the source contributions. The main aim of this study is to carry out source apportionment of PM10 for industrial locations of Vapi and Ankleshwar in Gujarat, using the Chemical Mass Balance (CMB) receptor model.&#x0D; Materials and methods: At six distinct locations of Ankleshwar and Vapi, respirable dust samplers were used to collect particulate matter on quartz filter sheets for the current study. Filter papers containing PM10 mass were subsequently examined for Water Soluble Ions (WSIs), major and trace elements, elemental and organic carbon followed by source apportionment study.&#x0D; Results: Using CMB, the contributions obtained for Ankleshwar are 27.85% for crustal or soil dust, 26.31% for fossil fuel combustion, 21.06% for vehicle emissions, 14.20% for secondary aerosols, 9.30% for biomass, and 1.20% for industrial emissions. CMB for Vapi revealed the chief source signatures as fossil fuel combustion including industries contributing 35%, crustal or soil dust contributing 22.90%, biomass burning contributing 19.12%, vehicular emissions contributing 16.18%, and secondary aerosols contributing 6.79%.&#x0D; Conclusion: By applying the CMB model, the primary source is found to be crustal or soil dust followed by burning fossil fuels, vehicular emissions, and secondary aerosols for Ankleshwar and Vapi, respectively. A quantitative assessment of source contributions to particulate matter is required to create emission control measures. The findings of this study will be beneficial for the environmental management of particle concentrations in the study region.

Occupational exposure to respirable crystalline silica among US metal and nonmetal miners, 2000-2019.

In metal and nonmetal (M/NM) mines in the United States, respirable crystalline silica (RCS) exposures are a recognized health hazard and a leading indicator of respiratory disease. This study describes hazardous exposures that exceed occupational exposure limits and examines patterns of hazardous RCS exposure over time among M/NM miners to better inform the need for interventions. Data for this study were obtained from the Mine Safety and Health Administration (MSHA) Open Government Initiative Portal for the years 2000-2019, examining respirable dust samples with MSHA-measured quartz concentration >1%. Descriptive statistics for RCS were analyzed for M/NM miners by year, mine type, sector, commodity, occupation, and location in a mine. This study found the overall geometric mean (GM) for personal exposures to RCS was 28.9 μg/m3 (geometric standard deviation: 2.5). Exposures varied significantly by year, mine type, sector, commodity, occupation, and location in a mine. Overall, the percentages of exposures above the MSHA permissible exposure limit (PEL for respirable dust with >1% quartz, approximately 100 μg/m3 RCS) and the National Institute for Occupational Safety and Health RCS recommended exposure limit (REL, 50 μg/m3 ) were 11.8% and 27.3%, respectively. GM exposures to RCS in 2018 (45.9 μg/m3 ) and 2019 (52.9 μg/m3 ) were significantly higher than the GM for all years prior. The overall 95th percentile of RCS exposures from 2000 to 2019 was 148.9 μg/m3 , suggesting a substantial risk of hazardous exposures above the PEL and REL during the entire period analyzed. The prevalence of high exposures to RCS among M/NM miners continues in the past 20 years and may be increasing in certain settings and occupations. Further research and intervention of the highest exposures are needed to minimize the risks of acquiring silica-induced respiratory diseases.

A Study of Respirable Silica in Underground Coal Mines: Particle Characteristics

Respirable crystalline silica is now considered to be a major culprit of resurgent lung disease among US coal miners—especially in central Appalachia—though questions remain regarding the specific circumstances around exposure to it. As part of a larger investigation of dust in 15 US coal mines, a recent study examined the silica content in both the respirable mine dust samples and the samples of respirable dust generated in the laboratory from primary source materials (i.e., coal and rock strata and rock dusting products). It concluded the rock strata that is being drilled for roof bolting or is being cut along with the coal is the most significant source of respirable silica in many mines, which is consistent with the expectations based on other scattered datasets. However, little information is available on the characteristics of respirable silica particles which might be important for understanding the exposure risks better. In the current study, which represents another part of the aforementioned investigation in 15 mines, scanning electron microcopy with energy dispersive X-ray spectroscopy (SEM–EDX) were used to analyze the size and surface condition (i.e., degree of surface-associated clay) of 1685 silica particles identified in 58 respirable mine dust samples. The results indicated that silica is typically finer in locations nearby to drilling and cutting activities than it is in other locations within a mine, but the silica in the Central Appalachian mines is not necessarily finer than it is in the mines in other regions. An analysis of the particle surfaces revealed that respirable silica in coal mines often does not occur as “free”, high-purity particles. Rather, there can be a range of occurrences including silica particles having a thin “occlusion” layer of clay, silica within agglomerates that can also contain other particle types including clays, or even silica ingrained within other particles such as coal.

Benefits and limitations of field-based monitoring approaches for respirable dust and crystalline silica applied in a sandstone quarry

With the advent of new sensing technologies and robust field-deployable analyzers, monitoring approaches can now generate valuable hazard information directly in the workplace. This is the case for monitoring respirable dust and respirable crystalline silica concentration levels. Estimating the quartz amount of a respirable dust sample by nondestructive analysis can be carried out using portable Fourier transform infrared spectroscopy (FTIR) units. Real-time respirable dust monitors, combined with small video cameras, allow advanced assessments using the Helmet-CAM methodology. These two field-based monitoring approaches, developed by the National Institute for Occupational Safety and Health (NIOSH), have been trialed in a sandstone quarry. Twenty-six Helmet-CAM sessions were conducted, and forty-one dust samples were collected around the quarry and analyzed on-site during two events. The generated data generated were used to characterize concentration levels for the monitored areas and workers, to identify good practices, and to illustrate activities that could be improved with additional engineered control technologies. Laboratory analysis of the collected samples complemented the field finding and provided an assessment of the performance of the field-based techniques. Only a fraction of the real-time respirable dust monitoring sessions data could be corrected with laboratory analysis. The average correction factor ratio was 5.0. Nevertheless, Helmet-CAM results provided valuable information for each session. The field-based quartz monitoring approach overestimated the concentration by a factor of 1.8, but it successfully assessed the quartz concentration trends in the quarry. The data collected could be used for the determination of a quarry calibration factor for future events. The quartz content in the dust was found to vary from 14% to 100%, and this indicates the need for multiple techniques in the characterization of respirable dust and quartz concentration and exposure. Overall, this study reports the importance of the adoption of field-based monitoring techniques when combined with a proper understanding and knowledge of the capabilities and limitations of each technique.

Characterization of the Emissions and Crystalline Silica Content of Airborne Dust Generated from Grinding Natural and Engineered Stones.

In this study, we systematically characterized the airborne dust generated from grinding engineered and natural stone products using a laboratory testing system designed and operated to collect representative respirable dust samples. Four stone samples tested included two engineered stones consisting of crystalline silica in a polyester resin matrix (formulations differed with Stones A having up to 90wt% crystalline silica and Stone B up to 50wt% crystalline silica), an engineered stone consisting of recycled glass in a cement matrix (Stone C), and a granite. Aerosol samples were collected by respirable dust samplers, total dust samplers, and a Micro-Orifice Uniform Deposit Impactor. Aerosol samples were analyzed by gravimetric analysis and x-ray diffraction to determine dust generation rates, crystalline silica generation rates, and crystalline silica content. Additionally, bulk dust settled on the floor of the testing system was analyzed for crystalline silica content. Real-time particle size distributions were measured using an Aerodynamic Particle Sizer. All stone types generated similar trimodal lognormal number-weighted particle size distributions during grinding with the most prominent mode at an aerodynamic diameter of about 2.0-2.3 μm, suggesting dust formation from grinding different stones is similar. Bulk dust from Stone C contained no crystalline silica. Bulk dust from Stone A, Stone B, and granite contained 60, 23, and 30wt% crystalline silica, respectively. In Stones A and B, the cristobalite form of crystalline silica was more plentiful than the quartz form. Only the quartz form was detected in granite. The bulk dust, respirable dust, and total dust for each stone had comparable amounts of crystalline silica, suggesting that crystalline silica content in the bulk dust could be representative of that in respirable dust generated during grinding. Granite generated more dust per unit volume of material removed than the engineered stones, which all had similar normalized dust generation rates. Stone A had the highest normalized generation rates of crystalline silica, followed by granite, Stone B, and Stone C (no crystalline silica), which likely leads to the same trend of respirable crystalline silica (RCS) exposure when working with these different stones. Manufacturing and adoption of engineered stone products with formulations such as Stone B or Stone C could potentially lower or eliminate RCS exposure risks. Combining all the effects of dust generation rate, size-dependent silica content, and respirable fraction, the highest normalized generation rate of RCS consistently occurs at 3.2-5.6 µm for all the stones containing crystalline silica. Therefore, removing particles in this size range near the generation sources should be prioritized when developing engineering control measures.

Evaluation of occupational exposure to wood dust among sawmill workers within the Gert Sibande District Municipality, South Africa.

Wood dust is regarded as one of the human carcinogen based on an increased risk of nasal and sinonasal cancer. This study was conducted in two sawmills to measure and determine the time-weighted average (TWA) exposure level to wood dust, and compare the results with the South African occupational exposure limit (OEL). Personal and area respirable and total inhalable wood dust samples were collected using calibrated Giliair-3 personal air sampling pump (Sensidyne, USA). Data was analysed using Microsoft Office Excel 2019 Analysis Tool Pak for a summary of descriptive statistics. Both the geometric means and standard deviation as well as the minimum and maximum values were calculated. The geometric mean = GM (geometric standard deviation = GSD) for personal respirable wood dust exposure at sawmill A was 0.9(4.8) mg/m3 while at sawmill B - 0.57(0.75) mg/m3. The GM(GSD) for personal total inhalable wood dust exposure at sawmill A was 0.37(0.94) mg/m3 while at sawmill B - 1.19(16.91) mg/m3. Besides that, the GM(GSD) for area respirable wood dust at sawmill A was 0.13(0.09) mg/m 3 , while at sawmill B - 0.8(0.6) mg/m3. Likewise, the GM(GSD) for area total inhalable wood dust at sawmill A was 0.13(0.16) mg/m3 while at sawmill B - 0.54(0.55) mg/m3 . Results for the majority of samples were below the OEL. Workers smoking tobacco or cigarettes should be encouraged to stop smoking since smoking, especially when associated with exposure to wood dust, may increase the risk of respiratory health symptoms.

Thermogravimetric Analysis of Respirable Coal Mine Dust for Simple Source Apportionment

ABSTRACT Resurgence of coal mine dust lung diseases in the central Appalachian region of the United States and elsewhere has spurred a range of efforts to better understand respirable coal mine dust (RCMD) exposures and sources. Thermogravimetric analysis (TGA) of RCMD samples can enable the dust mass to be fractionated into three main components: coal, non-carbonate minerals, and carbonates. These are expected to approximate, respectively, the three primary dust sources in many underground mines: the coal seam being mined, the surrounding rock strata (i.e., typically dominated by non-carbonate minerals) being drilled or mined along with the coal, and the rock dust products (i.e., typically made from carbonate-rich limestone or dolostone) being applied in the mine to mitigate explosibility hazards. As proof of concept, TGA was applied to respirable dust samples that were laboratory-generated from real source materials representing 15 mines. Except in the case of two mines, compositional results were generally consistent with expectations. TGA was also applied to RCMD samples collected in standard locations of 23 mines (including the 15 mines represented by the dust source materials). Results showed significantly different compositions with respect to sampling location and geographic region (i.e., within and outside of central Appalachia). To further interpret the RCMD results, a simple source apportionment model was built using the dust compositions yielded from the source materials analysis. Model results indicated that, on average, about twice as much dust was sourced from mining into rock strata than from mining the target coal seam. This finding is particularly important for mines extracting relatively large amounts of rock along with the coal or for mines that frequently encounter high-silica rock strata.

Exploring temporal variation of PM2.5 and PM10 and their association with meteorological data in Raipur, Chhattisgarh

While significant efforts have been made to mitigate the negative health impacts of particulate matter, there are limited statistics on particle exposure in Raipur. A study was conducted to look at the short-term relationships between particulate matter (PM2.5 and PM10) and meteorological variables in Raipur. The current research was based on an experimental study conducted at Chhattisgarh’s NIT Raipur. During the pre-monsoon, monsoon, post-monsoon, and winter seasons of 2021, a total of 125 air specimens were gathered from the campus. A respirable dust sampler and a fine particulate sampler were used to detect PM10 and PM2.5 on the building’s terrace. To assess the associations between PM2.5 and PM10 particulates and both sampling season and site, Pearson’s correlation study was used. The monthly mean mass concentrations of PM2.5 and PM10 in Raipur ranged from 28.0-334.0 μg/m3 to 56.0-448.0 μg/m3, respectively. Post-monsoon PM concentrations were highest, followed by pre-monsoon, winter, and post-monsoon. On more than 92 percent of days, PM2.5 concentrations exceeded NAAQS standards, while PM10 concentrations exceeded restrictions on 90 percent of days. There were seasonal changes identified in the relationships between PM concentrations and meteorological variables.