Total Dust Samples Research Articles

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.

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.

Wood Dust in Furniture Manufacturing: An Exposure Determinant Study in Ağrı City

Wood dust exposed during furniture manufacturing processes causes a variety of health problems. The aim of this study is to determine the respirable and inhalable dust exposure of the employees in small-scale furniture workshops located in Ağrı Organised Industrial Zone. For this purpose, the amount of dust exposure in the working environment was measured and the results were compared with the limit values in national and international legislation. Five furniture carpentry workshops in Ağrı Industrial Zone employing less than 10 workers constituted the universe of the study. A total of 22 people work in five workplaces. A total of 15 employees, 3 from each workshop, participated in the study. In this study, "MDHS 14/3: Gravimetric analysis and sampling method of respirable and inhalable dusts" was used for dust sampling. In the study, 30 respirable dust samples and 5 inhalable(total) dust samples were obtanied at 5 workplaces. Based on these measurement results, a daily TWA was calculated for each employee according to the TS EN 689 standard. The results were compared with the values in the national and international standards. It was concluded that the exposed values for dust concentration obtained from only one workplace were below the national and international limit values. It has been observed that a large part of both respirable and inhalable dust exposure values in workplaces exceeded the limit values. Practices and regulations such as tax reductions, incentives and projects that will contribute to the fight against dust in small-scale enterprises should be made.

Relationships between inhalable and total hexavalent chromium exposures in steel passivation, welding and electroplating operations of Ontario.

The main aim of the study was to assess the relationship between inhalable hexavalent chromium and "total" hexavalent chromium. Air sampling was conducted at steel passivation operation of a steel manufacturer at a stainless steel welding operation and at two hard chrome electroplaters. Air samples were taken side-by-side for "total" dust using closed-face 37-mm diameter cassette samplers and for inhalable dust using Institute of Occupational Medicine inhalable samplers. A total of 40 pairs of total and inhalable dust samples were collected and later analyzed. The range of "total" dust and inhalable dust concentrations in μg/m3 measured were 30-410 and 0.02 to 740 respectively for steel passivation; 260 to 1520 and 477 to 6970 for welding; and 0.01 to 1500 and 204 to 2130 for electroplaters. The range of "total" dust hexavalent chromium and inhalable dust hexavalent chromium concentrations in μg/m3 were 0.02-89 and 0.02 to 150 respectively for steel making; 4.1 to 4.9 and 2.2 to 6.9 for welding and 0.01 to 9.3 and 0.01 to 21 for electroplaters. A linear relationship between inhalable hexavalent chromium and "total" hexavalent chromium was found with a slope of 1.4 (CI:1.3, 1.5) and 0 offset. A ratio of 1.4 can thus be used as a conversion factor to convert previous data of hexavalent chromium taken on "total" dust basis to inhalable hexavalent chromium concentrations.

Silicosis in rhinestone-manufacturing workers in South China.

Silicosis is caused by long-term exposure to silica dust. Crystal rhinestone workers can be exposed to high levels of silica dust and are at risk of silicosis. To explore silicosis cases, silica dust exposure and control measures in a rhinestone factory in South China. We extracted and analysed data on new silicosis cases reported to China's occupational disease and occupational health information monitoring system between 2006 and 2012 from a rhinestone factory in South China. We measured the quartz content of bulk dust, static total and respirable dust samples. Ninety-eight silicosis cases were reported between 2006 and 2012. The mean duration of silica dust exposure was 9.2 years (range 3-16). Drilling and polishing workers accounted for 96 (98%) of cases. We collected 1479 static samples including 690 total dust and 789 respirable dust samples. Mean dust levels for drilling were 1.01 mg/m3 (range 0.20-3.80) for total dust and 0.51 mg/m3 (range 0.04-1.70) for respirable dust. Mean dust levels for polishing were 0.59 mg/m3 (range 0.20-2.10) for total dust and 0.28 mg/m3 (range 0.08-0.71) for respirable dust. Over a third [289/789 (37%)] of total dust samples and 129/690 (19%) respirable dust samples exceeded the national permissible exposure limit. Exposure to silica dust, ineffective dust control measures and inefficient health surveillance may have contributed to the incidence of silicosis in the factory we studied. Identification of silica dust exposure and effective dust control measures would reduce the risk of silicosis in rhinestone workers.

Risk Quotient (RQ) Analysis in Workers Exposed to Respirable Dust in Ceramic Industry

Ceramics are produced from mashed clay, made using high temperatures with long durability so that the clay powder becomes very dry, triggering the spread of dust in the work environment. The very small dust, when inhaled, is able to enter the lungs, causing health problems to workers. To identify health problems that can occur to the workers, risk analysis is needed to determine the level of risk in the workers. This study aims to analyze the risk of workers exposed to respirated dust in ceramics industry. This study was an observational study using a cross sectional approach. The population in this study were all workers who worked in the production sector in ceramics industry comprising 30 workers. The sample in this study was the study population, consisting of 30 workers. Exposure to respirable dust on the respondents was measured using total dust sampling, indicating that 53.3% of the respondents had values exceeding the threshold 1, which means that they had a risk of being unsafe against exposure to respirated dust, so that they were at risk of developing health problems. Actions that can be taken to minimize the adverse effects of dust in work environment are by controlling dust at the source, using Personal Protective Equipment (PPE) at work, and periodic physiological pulmonary health examination.

Determination of legacy and novel brominated flame retardants in dust from end of life office equipment and furniture from Pretoria, South Africa

Indoor dust is known to be a source of human exposure to brominated flame retardants (BFRs) and these consists of the legacy polybrominated diphenyl ethers (PBDEs), total hexabromocyclododecane (T-HBCDD) and the “Novel or alternate” Brominated flame retardants (NBFRs). In this study, x-ray fluorescence (XRF) analyser was employed to measure elemental bromine contents in office furniture and electronics as the first indication of the possible presence of BFRs. To investigate the possible BFRs present, a total of 21 dust samples were collected from surfaces of electronic equipment and office furniture and were analysed using gas chromatography–mass spectrometry (GC–MS). The concentrations of ∑7 BDE- congeners ranged from 50 to 3346ngng−1. Of the ∑7 BDE congeners analysed, BDE-209, −183 and −99 were the most dominant congeners. The concentrations observed ranged from <LOD - 1758, <LOD - 401 and <LOD-543ngg−1, for BDE-209, −183 and −99, respectively. T-HBCDD and 2-ethyl-1-hexyl-2.3.4.5-tetrabromobenzoate (EH-TBB) were detected in 57 and 67% of the total dust samples analysed with concentrations ranging from <LOD - 673 and <LOD – 385ngg−1, respectively. However, Bis (2-ethylhexyl) tetrabromophthalate (BEH-TEBP) was only detected in 24% of the 21 samples exhibiting a concentration range of <LOD - 63ngg−1. The detection frequency of 1,2 Bis (2.4.6-tribromophenoxy) ethane (BTBPE) was 81% with concentrations of <LOD-1402ngg−1. Alongside the legacy BFRs, NBFRs were the most detected indicating probably increased usage as replacements for the banned commercial PBDEs products namely, penta-, octa-, and deca-BDE mixtures. No correlation was observed between the bromine levels obtained using portable XRF and the BFRs detected using GC–MS (r=0.0073, p=0.076). The observed trend may be attributed to various factors including the sample matrix analysed and the number of BFRs analysed. The observed trend is consistent with those reported from other studies.

Source apportionment and health risk assessment of potentially toxic elements in road dust from urban industrial areas of Ahvaz megacity, Iran.

This study investigates the occurrence and spatial distribution of potentially toxic elements (PTEs) (Hg, Cd, Cu, Mo, Pb, Zn, Ni, Co, Cr, Al, Fe, Mn, V and Sb) in 67 road dust samples collected from urban industrial areas in Ahvaz megacity, southwest of Iran. Geochemical methods, multivariate statistics, geostatistics and health risk assessment model were adopted to study the spatial pollution pattern and to identify the priority pollutants, regions of concern and sources of the studied PTEs. Also, receptor positive matrix factorization model was employed to assess pollution sources. Compared to the local background, the median enrichment factor values revealed the following order: Sb>Pb>Hg>Zn>Cu>V>Fe>Mo>Cd>Mn>Cr≈Co≈Al≈Ni. Statistical results show that a significant difference exists between concentrations of Mo, Cu, Pb, Zn, Fe, Sb, V and Hg in different regions (univariate analysis, Kruskal-Wallis test p<0.05), indicating the existence of highly contaminated spots. Integrated source identification coupled with positive matrix factorization model revealed that traffic-related emissions (43.5%) and steel industries (26.4%) were first two sources of PTEs in road dust, followed by natural sources (22.6%) and pipe and oil processing companies (7.5%). The arithmetic mean of pollution load index (PLI) values for high traffic sector (1.92) is greater than industrial (1.80) and residential areas (1.25). Also, the results show that ecological risk values for Hg and Pb in 41.8 and 9% of total dust samples are higher than 80, indicating their considerable or higher potential ecological risk. The health risk assessment model showed that ingestion of dust particles contributed more than 83% of the overall non-carcinogenic risk. For both residential and industrial scenarios, Hg and Pb had the highest risk values, whereas Mo has the lowest value.

Characterization of airborne float coal dust emitted during continuous mining, longwall mining and belt transport.

Float coal dust is produced by various mining methods, carried by ventilating air and deposited on the floor, roof and ribs of mine airways. If deposited, float dust is re-entrained during a methane explosion. Without sufficient inert rock dust quantities, this float coal dust can propagate an explosion throughout mining entries. Consequently, controlling float coal dust is of critical interest to mining operations. Rock dusting, which is the adding of inert material to airway surfaces, is the main control technique currently used by the coal mining industry to reduce the float coal dust explosion hazard. To assist the industry in reducing this hazard, the Pittsburgh Mining Research Division of the U.S. National Institute for Occupational Safety and Health initiated a project to investigate methods and technologies to reduce float coal dust in underground coal mines through prevention, capture and suppression prior to deposition. Field characterization studies were performed to determine quantitatively the sources, types and amounts of dust produced during various coal mining processes. The operations chosen for study were a continuous miner section, a longwall section and a coal-handling facility. For each of these operations, the primary dust sources were confirmed to be the continuous mining machine, longwall shearer and conveyor belt transfer points, respectively. Respirable and total airborne float dust samples were collected and analyzed for each operation, and the ratio of total airborne float coal dust to respirable dust was calculated. During the continuous mining process, the ratio of total airborne float coal dust to respirable dust ranged from 10.3 to 13.8. The ratios measured on the longwall face were between 18.5 and 21.5. The total airborne float coal dust to respirable dust ratio observed during belt transport ranged between 7.5 and 21.8.

An artifact-minimizing method for total dust sampling and chemical characterization of industrial high-temperature aerosols

ABSTRACTConventional methods for total dust sampling from industrial high-temperature aerosols containing condensable species, e.g., in boilers of municipal solid waste incinerators (MSWI), are always influenced by condensation artifacts. Therefore, we extended the scope of a previously developed probe intended for size-fractionated aerosol sampling with reduced artifacts and employed it for total dust measurements. The dust is collected on quartz fiber filters, which are gravimetrically evaluated and chemically analyzed by energy dispersive X-ray spectroscopy and wet-chemical methods. First measurements in the boiler of an MSWI confirm that the probe is also suitable for artifact-minimized total dust sampling. The data are consistent with results from measurements with the size-fractionating method conducted in parallel. By combining the results of both sampling methods, we reveal the average chemical composition of the submicron particles in the aerosol, which is not accessible by one of the two methods...

Dust exposure levels among treet sweepers in Bole Sub-City, Addis Ababa, Ethiopia

Background: Intensive manual street sweeping has been performed over the last three years in Addis Ababa to optimize the cleanliness of the surface of the street and make it convenient for public use. Street sweeping is a job, but it is a job that also has a direct link with the health of the sweepers. Street sweepers are severely exposed to street dust. Yet, the level of dust exposure among the sweepers has not been documented in Ethiopia. Objective: The aim of this study was to assess the level of exposure of dust to street sweepers in Addis Ababa city. Methods: An exposure study was conducted among 10 street sweepers, measuring exposure levels for four working days. The measurements were performed by total dust samplers (37 mm Millipore plastic cassette with a PVC filter) attached to the breathing zone of the workers. Gravimetric analysis of the filters was done using a Mettler Toledo XPE105 micro-balance (detection limit 0.01mg). The sampling cassettes with filter were conditioned in desiccators for 24 hours before weighing. A survey data sheet and an observational checklist were used to record exposure attributes. Data were analyzed using SPSS Version 20. The exposure levels were compared with the threshold limit value for total dust recommended by the American Conference of Governmental Industrial Hygienists of 10 mg/m 3 . Results: The study participants covered a total of 1km, and were sweeping from 6:00-9:00 am. The participants were assumed to constitute one similar exposure group as all sweepers covered four operations in performing the street sweeping: sweeping the street surface, collecting dust and litter in one place, putting it in a container and then disposing it at a disposal site designated for this purpose. The median dust exposure level (n=19 samples) was 10.71 mg/m 3 (IQR=7.43). This is above the threshold limit value of 10 mg/m 3 . Eleven of the samples exceeded the occupational exposure level. The exposure level did not vary significantly between sampling days. This indicates that the exposure variability is consistent across the four sampling days. Conclusion: The studied street sweepers were exposed to dust levels that exceeded the recommended exposure level. Additional comprehensive research in a larger exposed population is suggested to further identify the most important determinants for high exposure levels among street sweepers. Studying characteristics of the street dust is another suggested area for future research. [ Ethiop. J. Health Dev. 2017;31(4):236-243] Keywords: Street sweeping, dust, exposure level, Addis Ababa, Ethiopia

토공사 현장에서 발생하는 공기 중 석영의 노출 평가

Objectives: The purpose of this study was to evaluate quartz concentrations in airborne total and respirable dusts. Materials: Respirable dust samples were collected using a 10 mm aluminum cyclone equipped with a 37 mm<TEX>$5{\mu}m$</TEX> pore size PVC filter. Total dust samples were collected with a three stage cassette from three work sections at earthwork sites located in the South Chungcheong-do Province area. Results: The geometric means of quartz concentrations were <TEX>$0.008mg/m^3$</TEX> and <TEX>$0.004mg/m^3$</TEX> in total dust and respirable dust, respectively. The geometric means of quartz contents analyzed by FTIR were 3.74% in total dust and 3.16% in respirable dust. The geometric mean of quartz concentrations and contents in secondary blasting operations were higher than those in other operations. Conclusions: Given that secondary blasting operations had higher quartz concentrations, there is a need to reduce respirable dust, such as through wet operations.

Effect of the Quartz Particle Size on XRD Quantifications and Its Implications for Field Collected Samples

The aims of the present study were to assess the effect of the quartz particle size on XRD quantifications, and use it to develop models for correcting the measured quartz concentrations of samples collected from the field. Seven nearly monodispersed pure quartz dusts, with mass median aerodynamic diameters (MMAD) ranging from 0.70 to 10.84 μm, were prepared by a liquid sedimentation device, and their unit XRD intensities (UI) were measured using the NIOSH Method 7500. The results show that UI increases (from 063 to 1.14) along with the rise in MMAD of the pure quartz dust. To examine the impact of the above results on quantifying field collected samples, both total dust and respirable dust samplings were conducted at seven different workplace environments. The results show that the quartz particles contained in all collected total dust samples (MMAD=5.18-16.7 μm, GSD=2.08-2.88) were coarser in their particle sizes than that of the reference quartz standard (NIST-SRM 1878; MMAD=2.16 μm, GSD=1.55), and the measured total quartz particle concentrations (C_m) were 16.6-22.5% lower than the corresponding true concentrations (C_t). However, for respirable dust samples (MMAD=1.37-3.95 μm, GSD=1.978-2.87), since collected quartz particle sizes could be either finer or coarser than that of the reference standard, both underestimation and overestimation were found in the present study (C_m/C_t=0.881-1.09). To correct the measured concentrations of field collected samples, correcting models were developed based on the MMADs of the collected quartz particle samples and their corresponding UIs. This study yields correcting factors for the respirable fraction (CR_f) as CR_f=1.50-0.67×[1-exp(-0.69×MMAD)] (R^2=0.996, n=7). However, the obtained CR_f should be used with caution if the collected samples were found with quartz particle sizes falling outside the size range of the present study.

A comparison of real-time monitoring of select metal concentrations in a copper smelter workplace compared to standard pump air sampling monitoring methods

This research was conducted to determine if a direct-reading instrument can be used as a guidance tool to estimate the concentrations of arsenic, cadmium, copper and lead in air within a copper smelter workplace based on comparison to standard pump-filter air sampling monitoring methods for these agents. Both respirable and total dust samples were collected using precision flow air sampling pumps and mixed cellulose ester (MCE) filters in sampling cassettes to determine the concentration for each of these metals in air in a smelter workplace. Particulate matter with a diameter of 10 μm or less (PM 10 ) was also sampled by using air sampling pumps and PM 10 impactors. Samples collected in the smelter workplace were submitted to an American Industrial Hygiene Association (AIHA) accredited analytical laboratory, where gravimetric analyses for the total weight of particulates were measured and the concentration of each of the four metals of interest was determined. During the collection of the MCE filters-cassette and PM 10 impactor samples, a Haz-Dust real-time, direct-reading instrument was simultaneously used to measure particulate concentrations in air. A Pearson's Correlation was calculated to determine the strength or degree of association between the direct-reading instrument results and metal concentration for the respirable, total dust and PM 10 concentrations reported by the laboratory. Linear regression was then performed between the direct-reading results and each specific metal concentration reported by the laboratory for total, respirable and PM 10 samples. This comparison of the data from the different monitoring methods provided a correction factor, which was then used to predict the metal concentrations in air based on the direct-reading instrument readings. Pearson's Correlation results showed correlation coefficients from −0.14 for respirable lead to 0.49 for copper PM 10 compared to direct-reading instrument results. Linear regression results found R 2 values ranging from 0.581 for lead PM 10 compared to the direct-reading instrument to 0.821 for copper total dust as compared to the direct-reading instrument aerosol measurements. The direct-reading instrument appears valid and reliable for obtaining general estimates of some metals in a copper smelter workplace, however the method is not sufficiently accurate to replace current accepted, and in some cases required, pump-filter air monitoring methods and should therefore only be used as a guidance tool.

Beryllium Aerosol Characteristics in the Magnesium and Aluminum Transformation Industry in Quebec: A Comparison of Four Different Sampling Methodologies

To examine the influence of the sampling method on beryllium (Be) exposure assessment, a study was conducted in foundries and smelters to contrast the performance of five different dust sampling devices. Six sampling surveys were conducted in four different settings, and both personal and fixed station samples were collected using the following sampling heads: IOM samplers (inhalable dust), 35-mm plastic cassettes (total dust), aluminum SKC cyclones (respirable dust), 8-stage Sierra cascade impactors, and 12-stage MOUDI impactors. In total, beryllium concentrations were determined for 66/68 inhalable dust samples, 62/62 total dust samples, 56/57 respirable dust samples, 54/64 8-stage Sierra samples, and 19/25 12-stage MOUDI samples. In the magnesium foundry and aluminum smelters, the concentrations obtained during specific tasks could exceed the actual permissible exposure limit of the province of Québec (0.15 μg/m 3 ) or of the ACGIH threshold limit value (TLV) (0.05 μg/m 3 ). The median of median dust concentration ratios computed from the sampling heads at the fixed station decreased as follows: IOM (1.00) > Sierra (0.76) > 37-mm cassette (0.61) > MOUDI (0.48) > respirable (0.12). The same trends were observed with the ratios of the median of median Be concentrations at the fixed station but with a larger scattering within sampling heads as follows: IOM (1.00) > Sierra (0.69) > 37-mm cassette (0.64) > MOUDI (0.54) > respirable (0.19). The median of median ratios of dust (IOM (1.00) > Sierra (0.56) > 37-mm cassette (0.35) > respirable (0.06)) and Be (IOM (1.00) > Sierra (0.66) > 37-mm cassette (0.48) > respirable (0.11)) in dust were lower, and there was less scattering for the 37-mm cassette and SKC cyclone used during breathing zone sampling than for the same sampling heads at the fixed station. Inhalable aerosol measurements should remain the tool for estimating the risk of exposure to beryllium in these settings until a clear dose response is established for these sampling heads.

Monitoring concentrations of select metals in workplace smelter airborne particulates using a Grimm 1.109 Real-time Portable Aerosol Spectrometer

Particulates containing hazardous metals and metal fumes are common in the metal smelting industry. Exposure of workers to these smelter particulates has been documented to lead to adverse health effects. In this study, select metals contained in respirable, PM10, and total dust samples where correlated to readings of a Grimm 1.109 aerosol measuring instrument in an effort to see if with the use of correction factors the metals can be accurately determined when compared to metal concentrations reported by the laboratory analysis of respirable, PM10, and total dust samples. In all, there were 16 sampling events, with three respirable, three PM10, and three total dust samples collected during each sampling event. The four metals of particular interest analyzed by the laboratory were cadmium, arsenic, lead, and copper. To more accurately and precisely determine metal concentrations when using the Grimm 1.109 with correction factors, further sampling is needed with the collection of process variables such as ore feedstock metal concentrations, process operation parameters, and weather conditions that can be included into linear regression models. Statistical model results suggest that this methodology of using metal specific correction factors to adjust Grimm 1.109 measured particulate matter concentrations to determine the selected metal concentrations in a smelter environment are within statistically accepted criteria and can be used to determine the metal concentrations in the smelter industry.

Seasonal Variability of Culturable Fungal Genera in the House Dust of Inner-City Residences

House dust samples were collected up to six times over a 1-year period to explore seasonal variability of individual fungal genera in inner-city households in Minneapolis, Minnesota. General linear mixed-effects models were used to explore the variability of 13 fungal genera (Cladosporium, yeasts, Aureobasidium, Alternaria, Penicillium, Epicoccum, Mucor, Rhodotorula, Aspergillus, sterile fungi, Phoma, Pithomyces, and Fusarium) found in more than 20% of total dust samples. The five most common fungi (% of samples detected) were Cladosporium (81%), yeasts (63%), Aureobasidium (57%), Alternaria (56%), and Penicillium (55%), with the remaining genera found in 20–50% of the samples. When expressed as frequency of occurrence (%), genus fraction of total fungal concentration (%), or concentration of individual genera (CFU/g), these five genera also varied substantially by season. In contrast, Aureobasidium, Fusarium, and Mucor levels remained relatively constant throughout the year. The observed concentrations of the five most common fungal genera were higher than levels associated with increased respiratory symptoms reported in previous studies. Our results indicate that seasonal variability in common fungal genera is large: within-home to between-home variance ratios of Penicillium (4.1), Alternaria (4.9), Cladosporium (7.1), and yeasts (20.3) were substantially larger than that observed for total fungi (2.5). These results suggest that future studies attempting to link individual fungal genera to health effects need to characterize and control for this seasonal variability.

Exposure to fibres, crystalline silica, silicon carbide and sulphur dioxide in the norwegian silicon carbide industry.

Objectives: The aim of this study was to assess personal exposure to fibres, crystalline silica, silicon carbide (SiC) and sulphur dioxide in the Norwegian SiC industry.Methods: Approximately 720 fibre samples, 720 respirable dust samples and 1400 total dust samples were collected from randomly chosen workers from the furnace, processing and maintenance departments in all three Norwegian SiC plants. The respirable dust samples were analysed for quartz, cristobalite and non-fibrous SiC content. Approximately 240 sulphur dioxide samples were collected from workers in the furnace department.Results: The sorting operators from all plants, control room and cleaning operators in Plant A and charger, charger/mix and payloader operators in Plant C had a geometric mean (GM) of fibre exposure above the Norwegian occupational exposure limit (OEL) (0.1 fibre cm−3). The cleaner operators in Plant A had the highest GM exposure to respirable quartz (20 μg m−3). The charger/mix operators in Plant C had the highest GM exposure to respirable cristobalite (38 μg m−3) and the refinery crusher operators in Plant A had the highest GM exposure to non-fibrous SiC (0.65 mg m−3). Exposure to the crystalline silica and non-fibrous SiC was generally low and between 0.4 and 2.1% of the measurements exceeded the OELs. The cleaner operators in Plant A had the highest GM exposure to respirable dust (1.3 mg m−3) and total dust (21 mg m−3). GM exposures for respirable dust above the Norwegian SiC industry-specific OEL of 0.5 mg m−3 were also found for refinery crusher operators in all plants and mix, charger, charger/mix and sorting operators in Plant C. Only 4% of the total dust measurements exceeded the OEL for nuisance dust of (10 mg m−3). Exposure to sulphur dioxide was generally low. However, peaks in the range of 10–100 p.p.m. were observed for control room and crane operators in Plants A and B and for charger and charger/mix operators in Plant C.Conclusion: Workers in the SiC industry are exposed to a mixture of several agents including SiC fibres, quartz, cristobalite, non-fibrous SiC and sulphur dioxide. Exposure levels were generally below the current Norwegian OELs; however, high exposure to fibres and respirable dust still occurs in the furnace department.

Agricultural Dust Production in Standard and Conservation Tillage Systems in the San Joaquin Valley

The negative health effects of repeated dust exposure have been well documented. In California's San Joaquin Valley, agricultural operations may contribute substantially to airborne particulates. We evaluated four management systems to assess impacts on dust production and soil properties for a cotton (Gossypium hirsutum L.)-tomato (Lycopersicon esculentum Mill.) rotation: standard tillage with (STCC) and without (STNO) cover crop, and conservation tillage with (CTCC) and without (CTNO) cover crop. Gravimetric analysis of total dust (TD, <100-mum aerodynamic diameter) and respirable dust (RD, 4-mum aerodynamic diameter) samples collected in the plume generated by field implements showed that dust concentrations for CTNO treatments were about one-third of their STNO counterparts for both cumulative TD and RD measured throughout the two-year rotation, primarily due to fewer in-field operations. The TD and RD production for STNO and STCC was comparable, whereas the CTCC system produced about twice as much TD and RD as CTNO. Energy dispersive spectroscopy (EDS) analyses showed absolute increases of 8 and 39% organic fragments in STCC and CTCC over STNO and CTNO, respectively, while organic fragments in the TD increased by 6% in both cover crop treatments. Soil C content was positively correlated with clay content and increased by an average of 0.12 and 0.07% in the cover crop and non-cover crop treatments, respectively, although soil C for each treatment showed a distinct response to a field texture gradient. While dust emissions show an immediate decrease due to fewer field operations for the conservation tillage treatments, long-term sampling is necessary to determine the effects that increased aggregation through organic matter additions may have on dust production.