Dust Measurements Research Articles

NEOWISE Observations of Distant Active Long-period Comets C/2014 B1 (Schwartz), C/2017 K2 (Pan-STARRS), and C/2010 U3 (Boattini)

Hyperactive comet activity typically becomes evident beyond the frost line (∼3–4 au) where it becomes too cold for water-ice to sublimate. If carbon monoxide (CO) and carbon dioxide (CO2) are the species that drive activity at sufficiently large distances, then detailed studies on the production rates of these species are extremely valuable to examine the formation of the solar system because these two species (beyond water) are next culpable for driving cometary activity. The NEOWISE reactivated mission operates at two imaging bandpasses, W1 and W2 at 3.4 μm and 4.6 μm, respectively, with the W2 channel being fully capable of detecting CO and CO2 at 4.67 μm and 4.23 μm in the same bandpass. It is extremely difficult to study CO2 from the ground due to contamination in Earth’s atmosphere. We present our W1 and W2 photometry, dust measurements, and findings for comets C/2014 B1 (Schwartz), C/2017 K2 (Pan-STARRS), and C/2010 U3 (Boattini), hereafter, B1, K2, and U3, respectively. Our results assess CO and CO2 gas production rates observed by NEOWISE. We have determined: (1) comets B1 and K2 have CO2 and CO gas production rates of ∼1027 and ∼1029 molecules s−1, respectively, if one assumes the excess emission is attributed to either all CO or all CO2; (2) B1 and K2 are considered hyperactive in that their measured Af ρ dust production values are on the order of ≳103 cm; and (3) the CO and CO2 production rates do not always follow the expected convention of increasing with decreased heliocentric distance, while B1 and K2 exhibit noticeable dust activity on their inbound leg orbits.

Cancer mortality in chrysotile miners and millers, Russian Federation: main results (Asbest Chrysotile Cohort-Study).

We investigated mortality in workers of the world's largest chrysotile mine and enrichment factories located in the town of Asbest, Russian Federation. This historical cohort study included all workers employed for at least 1 year between 1975 and 2010 and follow-up until the end of 2015. Cumulative exposure to dust was estimated based on workers' complete occupational history linked to dust measurements systematically collected from the 1950s. Exposure to chrysotile fibers was estimated using dust-to-fiber conversion factors. Relative risks (RRs) and 95% confidence intervals (CIs) were estimated as mortality rate ratios in Poisson regression models. A total of 30 445 (32% women) workers accumulated 721 312 person-years at risk and 11 110 (36%) died. Of the workers, 54% had more than 30 years since their first exposure. We found an exposure-response between cumulative dust and lung cancer mortality in men. No clear association with dust exposure but a modest increase in the highest category of fiber exposure was seen for lung cancer in women. Mesothelioma mortality was increased (RR = 7.64, 95% CI = 1.18 to 49.5, to at least 80 fibers per cm3 years and RR = 4.56, 95% CI = 0.94 to 22.1, to at least 150 mg/m3 years [dust]), based on 13 deaths. For colorectal and stomach cancer, there were inconsistent associations. No associations were seen for laryngeal or ovarian cancer. In this large-scale epidemiological study in the world's largest active asbestos mine, we confirmed an increased risk of mesothelioma with high fiber exposure and an increasing mortality for lung cancer in men with increasing dust exposure. Less clear-cut increased lung cancer mortality was seen in the women. Continued mortality follow-up is warranted.

Beyond Conventional Monitoring: A Semantic Segmentation Approach to Quantifying Traffic-Induced Dust on Unsealed Roads.

Road dust is a mixture of fine and coarse particles released into the air due to an external force, such as tire-ground friction or wind, which is harmful to human health when inhaled. Continuous dust emission from the road surfaces is detrimental to the road itself and the road users. Due to this, multiple dust monitoring and control techniques are currently adopted in the world. The current dust monitoring methods require expensive equipment and expertise. This study introduces a novel pragmatic and robust approach to quantifying traffic-induced road dust using a deep learning method called semantic segmentation. Based on the authors' previous works, the best-performing semantic segmentation machine learning models were selected and used to identify dust in an image pixel-wise. The total number of dust pixels was then correlated with real-world dust measurements obtained from a research-grade dust monitor. Our method shows that semantic segmentation can be adopted to quantify traffic-induced dust reasonably. Over 90% of the predictions from both correlations fall in true positive quadrant, indicating that when dust concentrations are below the threshold, the segmentation can accurately predict them. The results were validated and extended for real-time application. Our code implementation is publicly available.

Real Time Route Adjustment of a UAV Based on Dust Measurement with an Onboard Sensor

This research is driven by a pressing requirement to improve the effectiveness and safety of unmanned aerial vehicle (UAV) operations, specifically in atmospheric particle sensing. Airborne particulates present a substantial health hazard, leading to an increasing demand for inventive solutions capable of autonomously guiding UAVs along optimal routes, steering clear of regions with heightened dust concentrations. This research aims to address this challenge by developing a sophisticated approach that integrates atmospheric particle sensors with UAV flight control systems. The approach outlined in this study relies on atmospheric sensors mounted on a UAV to measure dust levels in a specified region. The UAV, following a predetermined route over the area, detects dust pollution. It dynamically adjusts its route based on the observed dust levels, avoiding areas with high concentrations of dust. This adaptive route determination aims to identify safe paths, avoiding regions with elevated dust levels that may pose risks to human health. The flight strategy and area-scanning methodology tailored for this objective are established, enabling the UAV to execute the assigned task. The ultimate goal is to create a system that not only minimizes energy consumption but also prioritizes human health by autonomously redirecting the UAV away from potentially harmful dust levels. The real-time monitoring and telemetry data feedback mechanisms further contribute to the advancement of UAV technology for environmental sensing and risk mitigation. Additionally, the integration of the laser-based dust sensor, i.e., Gp2y10, with the ArduPilot autopilot flight computer ensures seamless coordination, with the UAV adjusting its flight path based on the sensor's output.

Testing external photoevaporation in the σ-Orionis cluster with spectroscopy and disk mass measurements (Corrigendum)

{The evolution of protoplanetary disks is regulated by an interplay of several processes, either internal to the system or related to the environment. As most of the stars and planets, including our own Solar System, have formed in massive stellar clusters that contain OB-type stars, studying the effects of UV radiation on disk evolution is of paramount importance.} % aims heading (mandatory) {Here we test the impact of external photoevaporation on the evolution of disks in the mid-age ($sim$3--5 Myr) $sigma$-Orionis cluster by conducting the first combined large-scale UV to IR spectroscopic and mm-continuum survey of this region.} % methods heading (mandatory) {We study a sample of 50 targets located at increasing distances from the central, massive OB system $sigma$-Ori. We combine new spectra obtained with VLT/X-Shooter, used to measure mass accretion rates and stellar masses, with new and previously published ALMA measurements of disk dust and gas fluxes and masses.} % results heading (mandatory) {We confirm the previously found decrease of $M_{rm dust}$ in the inner $sim$0.5 pc of the cluster, and discover an additional dependence with the stellar host mass. The disks around the more massive stars ($ge$ 0.4msun) and located in the inner part ($<$ 0.5 pc) of the cluster have $M_{rm dust}$ about an order of magnitude lower than the more distant ones, in contrast to the rather flat $M_{rm dust}$ distribution as a function of the projected separation from $sigma$-Ori, for the disks around the lowest-mass stars in the sample. About half of the sample is located in the region of the $dot{M}_{rm acc}$ vs $M_{rm disk}$ expected by models of external photoevaporation, i.e. showing shorter disk lifetimes than expected for their ages. The shorter disk lifetimes is observed for all targets with projected separation from $sigma$-Ori $<$ 0.5 pc, proving that the presence of a massive stellar system affects disk evolution. } % conclusions heading (optional), leave it empty if necessary {External photoevaporation is a viable mechanism to explain the observed shorter disk lifetimes and lower $M_{rm dust}$ in the inner $sim$0.5 pc of the $sigma$-Orionis cluster, where the effects of this process are more pronounced. Follow-up observations of the low stellar mass targets are crucial to constrain disk dispersion time scales in the cluster and to confirm the dependence of the external photoevaporation process with stellar host mass. This work confirms that the effects of external photoevaporation are significant down to at least impinging radiation as low as $sim 10^{4}$ G$_0$. }

Analysis of Air and Water Quality at Coal Harbor in Muaro Jambi Regency

Secondary data obtained from the Safety, Health and Environment Department of PT. Winner Prima Sekata (PT. WPS) in Kemingking Dalam Village, Taman Rajo District, Muaro Jambi Regency, in 2022 it was discovered that there were cases of Acute respiratory infections (ARI). Therefore, a study was carried out regarding the analysis of air quality and water quality at the coal port location in Muaro Jambi Regency to determine the extent of the environmental impacts resulting from coal loading and unloading and stockpile activities at the Talang Duku port, Jambi Province. The research was conducted using quantitative survey and descriptive methods. Data analysis is quantitative in nature with the aim of testing predetermined hypotheses. Dust measurement results obtained between 7.98 - 10.00 mg/m3, The allowable dust threshold value is in accordance with the Minister of Manpower Circular Number. SE.01/MEN/1997 concerning the NAB of Chemicals in Workplace Air is 0.9 mg/m. So the dust level in the Muaro Jambi coal port working area exceeds the quality standards set by the Minister of Manpower. Results of calculating the output water pollution index pH and TSS at the PT Outlet point. The WPS of port locations in the period March – June 2023 in each month has a Pij value of 1.08, which means the average pH and TSS value of output water from PT. WPS is at status 1.0 < 1.09 < 5.0 with the description Lightly Polluted. Based on processing with SPSS version 27 using the One way Anova test, it was found that Fcount then H0 was rejected.

Erratum to: A Novel Coal Mine Dust Measurement System and Experimental Analysis

Erratum to: A Novel Coal Mine Dust Measurement System and Experimental Analysis

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.

Stochastic soiling loss models for heliostats in Concentrating Solar Power plants

Reflectance losses on solar mirrors due to soiling are a significant challenge for Concentrating Solar Power (CSP) plants. Soiling losses can vary significantly from site to site — with (absolute) reflectance losses varying from fractions of a percentage point up to several percentage points per day (pp/day), a fact that has motivated several studies in soiling predictive modelling. Yet, existing studies have so far neglected the characterization of statistical uncertainty in their parameters and predictions. In this paper, two reflectance loss models are proposed that model uncertainty: an extension of a previously developed physical model and a simplified model. A novel uncertainty characterization enables Maximum Likelihood Estimation techniques for parameter estimation for both models, and permits the estimation of parameter (and prediction) confidence intervals.The models are applied to data from ten soiling campaigns conducted at three Australian sites (Brisbane, Mount Isa, Wodonga). The simplified model produces high-quality predictions of soiling losses on novel data, while the semi-physical model performance is mixed. The statistical distributions of daily losses were estimated for different dust loadings. Under median conditions, the daily soiling losses for Brisbane, Mount Isa, and Wodonga are estimated as 0.53±0.66, 0.08±0.08, and 0.58±0.15 pp/day, respectively. Yet, higher observed dust loadings can drive average losses as high as 2 pp/day.Overall, the results suggest a relatively simple approach characterizing the statistical distributions of soiling losses using airborne dust measurements and short reflectance monitoring campaigns.

Quantifying the Impact of the Dust Torque on the Migration of Low-mass Planets

Disk solids are critical in many planet formation processes; however, their effect on planet migration remains largely unexplored. Here we assess this important issue for the first time by building on the systematic measurements of dust torques on an embedded planet by Benitez-Llambay & Pessah. Adopting standard models for the gaseous disk and its solid content, we quantify the impact of the dust torque for a wide range of conditions describing the disk/planet system. We show that the total torque can be positive and reverse inward planet migration for planetary cores with M p ≲ 10 M ⊕. We compute formation tracks for low-mass embryos for conditions usually invoked when modeling planet formation processes. Our most important conclusion is that dust torques can have a significant impact on the migration and formation history of planetary embryos. The most important implications of our findings are as follows. (i) For nominal dust-to-gas mass ratios ϵ ≃ 0.01, low-mass planets migrate outwards beyond the water ice-line if most of the mass in the solids is in particles with Stokes numbers St ≃0.1. (ii) For ϵ ≳ 0.02–0.05, solids with small Stokes numbers, St ≃ 0.01, can play a dominant role if most of the mass is in those particles. (iii) Dust torques have the potential to enable low-mass planetary cores formed in the inner disk to migrate outwards and act as the seed for massive planets at distances of tens of au.

Di-(2-Ethylhexyl) Phthalate (DEHP) in House Dust in Canadian Homes: Behaviors and Associations with Housing Characteristics and Consumer Products

Background. Di-(2-ethylhexyl) phthalate (DEHP), which is ubiquitous in indoor environments, was the predominant phthalate measured in house dust in the Canadian CHILD Cohort and was found to be associated with a large increased risk of childhood asthma. Objective. To inform interventions by identifying sources of DEHP in dust and assessing behaviors related to DEHP concentrations in house dust. Methods. DEHP levels were measured in 726 dust samples collected at ~3 months of age in CHILD as well as in ~50 homes at two time points (June and November) in the CHILD pilot study. DEHP metabolites were measured in urine for a subset of the ~3-month-old infants. Housing characteristics were assessed at the time of dust and urine collection. Numerous factors from these surveys were investigated as potential sources of DEHP using univariate analyses and multivariable regressions. Correlations between DEHP in dust and urinary metabolites and between repeat dust samples were examined to study the relationship between dust measurement and DEHP exposure. Results. Overall, DEHP dust concentrations were higher for lower-income families. Homes with vinyl flooring in the kitchen and bathroom showed higher levels of DEHP than those without vinyl flooring. The quantity of vinyl furniture and the presence of mold were associated with higher DEHP concentrations, while the use of mattress covers reduced concentration. No other significant associations were found. DEHP concentrations in dust were consistent over 6 months, although the correlation between dust and DEHP metabolites in urine was low. Conclusion. DEHP in house dust persisted over multiple months, contributed to infant internal exposure, and was associated with specific housing characteristics. These findings may inform the public on their choice of building materials and products, as well as future policies, aimed at reducing the health risk associated with exposures in the indoor environment especially for children.

Space Plasma Physics: A Review

Owing to the ever-present solar wind, our vast solar system is full of plasmas. The turbulent solar wind, together with sporadic solar eruptions, introduces various space plasma processes and phenomena in the solar atmosphere all the way to Earth’s ionosphere and atmosphere and outward to interact with the interstellar media to form the heliopause and termination shock. Remarkable progress has been made in space plasma physics in the last 65 years, mainly due to sophisticated in situ measurements of plasmas, plasma waves, neutral particles, energetic particles, and dust via space-borne satellite instrumentation. Additionally, high-technology ground-based instrumentation has led to new and greater knowledge of solar and auroral features. As a result, a new branch of space physics, i.e., space weather, has emerged since many of the space physics processes have a direct or indirect influence on humankind. After briefly reviewing the major space physics discoveries before rockets and satellites (Section I), we aim to review all our updated understanding on coronal holes, solar flares, and coronal mass ejections, which are central to space weather events at Earth (Section II), solar wind (Section III), storms and substorms (Section IV), magnetotail and substorms, emphasizing the role of the magnetotail in substorm dynamics (Section V), radiation belts/energetic magnetospheric particles (Section VI), structures and space weather dynamics in the ionosphere (Section VII), plasma waves, instabilities, and wave-particle interactions (Section VIII), long-period geomagnetic pulsations (Section IX), auroras (Section X), geomagnetically induced currents (GICs, Section XI), planetary magnetospheres and solar/stellar wind interactions with comets, moons and asteroids (Section XII), interplanetary discontinuities, shocks and waves (Section XIII), interplanetary dust (Section XIV), space dusty plasmas (Section XV), and solar energetic particles and shocks, including the heliospheric termination shock (Section XVI). This article is aimed to provide a panoramic view of space physics and space weather.

The prevalences and levels of occupational exposure to dusts and/or fibres (silica, asbestos and coal): A systematic review and meta-analysis from the WHO/ILO Joint Estimates of the Work-related Burden of Disease and Injury

The prevalences and levels of occupational exposure to dusts and/or fibres (silica, asbestos and coal): A systematic review and meta-analysis from the WHO/ILO Joint Estimates of the Work-related Burden of Disease and Injury

Development of a quantitative North and Central European job exposure matrix for wood dust.

Wood dust is an established carcinogen also linked to several non malignant respiratory disorders. A major limitation in research on wood dust and its health effects is the lack of (historical) quantitative estimates of occupational exposure for use in general population-based case-control or cohort studies. The present study aimed to develop a multinational quantitative Job Exposure Matrix (JEM) for wood dust exposure using exposure data from several Northern and Central European countries. For this, an occupational exposure database containing 12653 personal wood dust measurements collected between 1978 and 2007 in Denmark, Finland, France, The Netherlands, Norway, and the United Kingdom (UK) was established. Measurement data were adjusted for differences in inhalable dust sampling efficiency resulting from the use of different dust samplers and analysed using linear mixed effect regression with job codes (ISCO-88) and country treated as random effects. Fixed effects were the year of measurement, the expert assessment of exposure intensity (no, low, and high exposure) for every ISCO-88 job code from an existing wood dust JEM and sampling duration. The results of the models suggest that wood dust exposure has declined annually by approximately 8%. Substantial differences in exposure levels between countries were observed with the highest levels in the United Kingdom and the lowest in Denmark and Norway, albeit with similar job rankings across countries. The jobs with the highest predicted exposure are floor layers and tile setters, wood-products machine operators, and building construction labourers with geometric mean levels for the year 1997 between 1.7 and 1.9 mg/m3. The predicted exposure estimates by the model are compared with the results of wood dust measurement data reported in the literature. The model predicted estimates for full-shift exposures were used to develop a time-dependent quantitative JEM for exposure to wood dust that can be used to estimate exposure for participants of general population studies in Northern European countries on the health effects from occupational exposure to wood dust.

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

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

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.

Measurement of Fine/Ultrafine Dust Using Lenticular Fiber-Based Particulate Measurement Devices

Measurement of particulate matter (PM), i.e., fine/ultrafine dust, is important for monitoring our surrounding environment. We demonstrate the fabrication of lenticular fiber-based fine/ultrafine dust measurement devices for monitoring the density and size of dust. The plano-convex lenticular fibers were fabricated by the CO2 laser polishing technique. The optical lens, used in the conventional light scattering-based fine/ultrafine dust measurement devices, was replaced by a plano-convex lenticular optical fiber to reduce the size and complexity of the dust measurement device. We utilized a light-emitting diode as the light source of the fine/ultrafine dust density measurement device. The fabricated device could indicate the dust density level (good, normal, bad, and very bad) according to the Korean standard. To estimate the size of the dust particulates, we fabricated a dust size measurement device that consists of a compact laser diode, a lenticular fiber, and a photodetector. We are successful in estimating the size of both fine and ultrafine PMs by detecting the power of the scattered light coming from the dust particulates. The dust size down to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.9 \mu \text{m}$ </tex-math></inline-formula> was detected using our dust measurement device. Our proposed dust measurement devices are simple, small, and cost-effective and can be considered as a candidate for portable applications.

Assessment of paper dust exposure and chronic respiratory symptoms among paper factory workers in, Ethiopia; a comparative cross-sectional study

BackgroundWorkers in pulp and paper factories are continuously exposed to paper dust. Excessive exposure to paper dust can cause respiratory disease. Information about the prevalence of chronic respiratory symptoms and dust exposure levels among workers in pulp and paper factories is not available in Ethiopia. The aim of this study was, therefore, to assess personal total dust exposure levels, the prevalence of chronic respiratory symptoms and their associated risk factors among workers in Ethiopian pulp and paper factories.MethodsA comparative cross-sectional study was conducted. A total of 40 dust measurements were carried out on 20 randomly selected workers. To assess chronic respiratory symptoms and associated factors, 434 workers from two paper factories and controls were interviewed using a standard questionnaire adapted from the American Thoracic Society (ATS). Gravimetric analyses of the filters were undertaken using a standard microbalance. Poisson regression was performed for comparing the prevalence of symptoms and risk factors for the two groups. Multivariable analyses were conducted to identify factors associated with chronic respiratory symptoms.ResultThe arithmetic mean (AM) and geometric mean (GM) of dust exposure levels among the paper factories workers were 11.3 (± 7.7) and 10.2 (± 1.4) mg/m3 respectively. This exposure level exceeded the threshold limit value recommended for total dust (10 mg/m3). The prevalence of having at least one chronic respiratory symptom was about 51% among the workers in paper factories. The prevalence ratio of having chronic respiratory symptoms among paper factory workers was 5.6 times higher (PR = 6, 95% CI 3.5–10.3) than in the controls. Chronic respiratory symptoms were significantly associated with factors such as an educational status of less than grade 9, being employed in the work sections of the factories, having work experience of 5 years and above, working more than 8 h per day and having a past history of occupation and respiratory illnesses.ConclusionThe dust concentration in the paper factories exceeded the acceptable recommended limit value of 10 mg/m3. The prevalence of chronic respiratory symptoms among paper factory workers was higher than among controls. The main determining factors for chronic respiratory symptoms among the workers were the specific work section such as production section, low income, having past history of respiratory illnesses, the number of years of working and low educational status. This finding indicated the need for improving the working conditions in paper factories in Ethiopia.

Glyphosate in house dust and risk of childhood acute lymphoblastic leukemia in California

BackgroundResidential use of pesticides has been associated with increased risk of childhood acute lymphoblastic leukemia (ALL). We evaluated determinants of glyphosate concentrations in house dust and estimated ALL risk in the California Childhood Leukemia Study (CCLS). MethodsThe CCLS is a population-based case-control study of childhood leukemia in California. Among those < 8-years (no move since diagnosis/reference date), we collected dust (2001–2007) from the room where the child spent the most time while awake and measured > 40 pesticides. Three-to-eight years later, we collected a second sample from non-movers. We used Ultra-Performance Liquid Chromatography Tandem Mass Spectrometry to measure glyphosate (µg/g dust) for 181 ALL cases and 225 controls and for 45 households with a second dust sample. We used multivariable Tobit regression to evaluate determinants of glyphosate concentrations. Odds ratios (ORs) and 95 % confidence intervals (CI) were calculated for ALL and quartiles of the concentration (first samples) using unconditional logistic regression. We computed the within- and between-home variance and intraclass correlation coefficient (ICC). ResultsGlyphosate was frequently detected (cases: 98 %; controls: 99 %). Higher concentrations were associated with occupational pesticide exposure, nearby agricultural use, treatment for lawn weeds and bees/wasps, and sampling season. Increasing concentrations were not associated with ALL risk (adjusted ORQ4vsQ1 = 0.8, CI: 0.4–1.4). We observed similar null associations for boys and girls, Hispanics and non-Hispanic whites, and among those who resided in their home since birth (76 cases/117 controls) or age two (130 cases/176 controls). The ICC was 0.32 indicating high within-home temporal variability during the years of our study. ConclusionsWe observed higher concentrations in homes associated with expected predictors of exposure but no association with childhood ALL risk. Due to continuing use, potential exposure to young children is high. It will be important to evaluate risk in future studies with multiple dust measurements or biomarkers of exposure.

Measurement of visible dust emissions during almond nut-picking operations at various harvester settings

ABSTRACT Peak ambient dusts levels in the San Joaquin Valley (SJV) are often coincident with peak agricultural harvest seasons, particularly for nut orchards. Federal reference methods (FRMs), consist of mass-based sampling techniques, are designated to measure and analyze ambient dust concentrations. However, FRMs generally require meticulous attention to sampling details, tedious labor and logistics, and time-consuming dispersion calculations. This study used opacity-based techniques - the U.S. Environmental Protection Agency (EPA) Method 9 and the Digital Compliance Opacity Technique (DCOT) - to quickly measure relative dust intensity at different harvester settings, and to evaluate visible dust emission reductions using a new/low-dust nut harvester. Results indicate that old/conventional harvester at standard settings (3 mph ground speed and 900 rpm blower speed) produced visible dusts with opacities ranging from 23.3% - 29.0%. The dust plume generated from new/low-dust harvesters at similar settings registered lower opacity readings, with an average of 13.94%. The lowest average dust opacity (7.8%) was achieved when the separation fan was turned off. The present results validated the previous FRM emission findings that an old/conventional harvester has the highest PM emissions, but with a potential to achieve 50% reduction by adopting new/low-dust harvesters. Compared to an old harvester, the relative intensity of dusts was reduced by 40% - 51% for low-dust harvesters operated at lower ground speeds. Further dust reductions could be achieved by lowering the fan speed (58%) and operating at no fan/blower setting (66.4%). Both visible emission evaluation (VEE) techniques were able to provide rapid quantitative feedback on the effects of operational changes on emitted harvest dusts. At this stage, opacity-based techniques can potentially be adapted as a screening tool for identifying best management practices (BMP) in reducing harvest dusts, rather than to solely rely on FRM mass-based techniques. Implication: U.S. EPA VEE techniques are established, robust methods of dust measurement systems that can be adopted to evaluate visible dust mitigation strategies in the SJV, alongside the existing FRM protocols. The use of Method 9 and DCOT, as both non-disruptive and rapid dust measurement tools, can bring immediate impact concerning the goal of the almond industry to significantly reduce its PM emissions in the next coming years.