Static Sampling Research Articles

Impacts of Chinese spring festival on household PM2.5 pollution and blood pressure of rural residents.

Household air pollution (HAP) from residential combustion considerably affects human health in rural China. Large-scale population migration and rural lifestyle changes during the Spring Festival are supposed to change the household air pollution and health risks; however, limited field study has determined its impacts on HAP and short-term health outcomes. A field study was conducted in rural areas of Southern China before and during the Spring Festival to explore the associations between HAP and blood pressure considering different factors such as cooking fuel, heating fuel, and smoking. Stationary real-time PM2.5 monitors were used to measure PM2.5 concentrations of the kitchen, living room, and yard of 156 randomly selected households. Personal exposure to PM2.5 was calculated based on the results of stationary samplers and corresponding time local residents spent in different microenvironments, and one adult resident was recruited of each family for the blood pressure measurement. Both personal exposure to PM2.5 and blood pressures of local residents increased during Spring Festival compared to the days before the holiday. Based on generalized linear model coupled with dominance analysis approach, it was found that personal PM2.5 exposure was positively associated with the factors of population size and the types of cooking and heating fuels with the relative contributions of approximately 82%, and systolic blood pressure (SBP, 100-120mmHg as normal range for adults) was positively and significantly associated with personal PM2.5 exposures with the relative contribution of 11%. The findings in this study demonstrated that Spring Festival can give rise to increase of HAP and hypertension risks, also related to tremendous solid fuel use, suggesting further policy making on promoting cleaner energy in rural areas and more attention on large population migration during national holidays.

An Ensemble of Adaptive Surrogate Models Based on Local Error Expectations

An ensemble of surrogate models with high robustness and accuracy can effectively avoid the difficult choice of surrogate model. However, most of the existing ensembles of surrogate models are constructed with static sampling methods. In this paper, we propose an ensemble of adaptive surrogate models by applying adaptive sampling strategy based on expected local errors. In the proposed method, local error expectations of the surrogate models are calculated. Then according to local error expectations, the new sample points are added within the dominating radius of the samples. Constructed by the RBF and Kriging models, the ensemble of adaptive surrogate models is proposed by combining the adaptive sampling strategy. The benchmark test functions and an application problem that deals with driving arm base of palletizing robot show that the proposed method can effectively improve the global and local prediction accuracy of the surrogate model.

Characterization of inhalation exposure to gaseous elemental mercury during artisanal gold mining and e-waste recycling through combined stationary and personal passive sampling.

While occupational inhalation exposure to gaseous elemental mercury (GEM) has decreased in many workplaces as mercury is being removed from most products and processes, it continues to be a concern for those engaged in artisanal and small-scale gold mining or in recycling mercury-containing products. Recently, stationary and personal passive air samplers based on activated carbon sorbents and radial diffusive barriers have been shown to be suitable for measuring GEM concentrations across the range relevant for chronic health effects. Here, we used a combination of stationary and personal passive samplers to characterize the inhalation exposure to GEM of individuals living and working in two Ghanaian gold mining communities and working at a Norwegian e-waste recycling facility. Exposure concentrations ranging from <7 ng m-3 to >500 μg m-3 were observed, with the higher end of the range occurring in one gold mining community. Large differences in the GEM exposure averaged over the length of a workday between individuals can be rationalized by their activity and proximity to mercury sources. In each of the three settings, the measured exposure of the highest exposed individuals exceeded the highest concentration recorded with a stationary sampler, presumably because those individuals were engaged in an activity that generated or involved GEM vapors. High day-to-day variability in exposure for those who participated on more than one day, suggests the need for sampling over multiple days for reliable exposure characterization. Overall, a combination of personal and stationary passive sampling is a cost-effective approach that cannot only provide information on exposure levels relative to regulatory thresholds, but also can identify emission hotspots and therefore guide mitigation measures.

Challenge with a Personal Cascade Impactor Sampler in a Silicon Metal Smelter

ABSTRACT Cascade impactors are useful tools in the measurement of particle size mass distribution of workplace aerosols. The application of cascade impactors, however, is sometimes challenging. Personal aerosol samples were collected by Sioutas cascade impactors and respirable cyclones in parallel in a silicon (Si) metal smelter to investigate the different particulate matter (PM) fractions. In a second campaign, nine new air samples were collected with the Sioutas personal cascade impactors using stationary sampling. It was found that wall deposition was substantial in the upper stages of the Sioutas cascade impactors, which meant that quite often more PM was deposited on the inner walls of the impactor than on the filter substrates. At the same time, wall deposition did most probably not affect the collection of the finest particles (< 0.25 µm). Besides wall deposition of the particles, the effect of high PM concentration on the impactor performance, particle bouncing and blow off, high particle mass loading and impact fragmentation of the particle agglomerates were considered for explaining the malfunctioning of the Sioutas impactors in the Si metal smelter. Furthermore, concentrations of the finest PM fraction (< 0.25 µm) and respirable fraction both collected by personal sampling are reported and discussed in the paper.

Dynamic Sampling from Graphical Models

In this paper, we study the problem of sampling from a graphical model when the model itself is changing dynamically with time. This problem derives its interest from a variety of inference, learning, and sampling settings in machine learning, computer vision, statistical physics, and theoretical computer science. While the problem of sampling from a static graphical model has received considerable attention, theoretical works for its dynamic variants have been largely lacking. The main contribution of this paper is an algorithm that can sample dynamically from a broad class of graphical models over discrete random variables. Our algorithm is parallel and Las Vegas: it knows when to stop, and it outputs samples from the exact distribution. We also provide sufficient conditions under which this algorithm runs in time proportional to the size of the update on general graphical models as well as well-studied specific spin systems. In particular we obtain, for the Ising model (ferromagnetic or antiferromagnetic) and for the hardcore model the first dynamic sampling algorithms that can handle both edge and vertex updates (addition, deletion, and change of functions). The algorithms for both these models are efficient within regimes that are close to the respective uniqueness regimes, beyond which, even for the static and approximate sampling, no local algorithms were known or the problem itself is intractable. Our dynamic sampling algorithm relies on a local resampling algorithm and a new “equilibrium" property that is shown to be satisfied by our algorithm at each step and enables us to prove its correctness. This equilibrium property is robust enough to guarantee the correctness of our algorithm, helps us improve bounds on fast convergence on specific models, and should be of independent interest.

Compressive Sampling Using a Pushframe Camera

The recently described pushframe imager, a parallelized single pixel camera capturing with a pushbroom-like motion, is intrinsically suited to both remote-sensing and compressive sampling. It optically applies a 2D mask to the imaged scene, before performing light integration along a single spatial axis, but previous work has not made use of the architecture's potential for taking measurements sparsely. In this paper we develop a strongly performing static binarized noiselet compressive sampling mask design, tailored to pushframe hardware, allowing both a single exposure per motion time-step, and retention of 2D correlations in the scene. Results from simulated and real-world captures are presented, with performance shown to be similar to that of immobile and hence inappropriate for satellite use whole-scene imagers. A particular feature of our sampling approach is that the degree of compression can be varied without altering the pattern, and we demonstrate the utility of this for efficiently storing and transmitting multi-spectral images.

A Critical Review on the Implementation of Static Data Sampling Techniques to Detect Network Attacks

Given that Internet traffic speed and volume are growing at a rapid pace, monitoring the network in a real-time manner has introduced several issues in terms of computing and storage capabilities. Fast processing of traffic data and early warnings on the detected attacks are required while maintaining a single pass over the traffic measurements. To alleviate these problems, one can reduce the amount of traffic to be processed using a sampling technique and detect the attacks based on the sampled traffic. Different parameters have an impact on the efficiency of this process, mainly the applied sampling policy and sampling ratio. In this study, we investigate the statistical impact of sampling network traffic and quantify the amount of deterioration that the sampling process introduces. In this context, an experimental comparison of existing sampling techniques is performed based on their impact on several well-known statistical measures.

Q-space Conditioned Translation Networks for Directional Synthesis of Diffusion Weighted Images from Multi-modal Structural MRI.

Current deep learning approaches for diffusion MRI modeling circumvent the need for densely-sampled diffusion-weighted images (DWIs) by directly predicting microstructural indices from sparsely-sampled DWIs. However, they implicitly make unrealistic assumptions of static q-space sampling during training and reconstruction. Further, such approaches can restrict downstream usage of variably sampled DWIs for usages including the estimation of microstructural indices or tractography. We propose a generative adversarial translation framework for high-quality DWI synthesis with arbitrary q-space sampling given commonly acquired structural images (e.g., B0, T1, T2). Our translation network linearly modulates its internal representations conditioned on continuous q-space information, thus removing the need for fixed sampling schemes. Moreover, this approach enables downstream estimation of high-quality microstructural maps from arbitrarily subsampled DWIs, which may be particularly important in cases with sparsely sampled DWIs. Across several recent methodologies, the proposed approach yields improved DWI synthesis accuracy and fidelity with enhanced downstream utility as quantified by the accuracy of scalar microstructure indices estimated from the synthesized images. Code is available at https://github.com/mengweiren/q-space-conditioned-dwi-synthesis.

Numerical study of boron diffusion in CMT and related thermal fatigue near cold legs of an AP1000 nuclear power unit

AP1000 adapts Passive Core Cooling System to improve the safety. However, it is found that static diffusion under the difference of the boron concentration and sampling lead to boron loss, which makes the boron concentration in core makeup tank lower than the specification limits. Corresponding to this problem, replenishing high concentration boron water is a way to meet the requirements for boron concentration. Under this circumstance, this study numerically investigates the effect of static boron diffusion, sampling and replenishing on boron concentration. The results show that static diffusion and sampling have a slight impact on boron dilution, but in different ways. A larger replenishing flow rate is useful to enhance the boron mixture. However, that will result in a heavy heat load on the “T" connection of reactor coolant system and core makeup tank.

Exposure to Ultrafine Particles in the Ferroalloy Industry Using a Logbook Method.

Background: It is difficult to assess workers’ exposure to ultrafine particles (UFP) due to the lack of personal sampling equipment available for this particle fraction. The logbook method has been proposed as a general method for exposure assessment. This method measures the time and concentration components of the time-weighted average concentration separately and could be suitable for investigation of UFP exposure. Objectives: In this study, we have assessed workers’ exposure to UFP in a ferrosilicon plant. The main tasks of the furnace workers were identified, and the logbook method was used in combination with stationary measurements of UFP taken as close to the identified task areas as possible. In order to verify the results, respirable particles were collected using stationary sampling in close proximity to the UFP measuring instrument, and personal full-shift sampling of respirable particles was performed simultaneously. Thus, exposure to respirable particles determined using the logbook method could be compared to the results of standard measurement. Methods: The particle number concentration of ultrafine particles was determined using a NanoScan SMPS. Respirable particle concentration and exposure were determined using a sampling train consisting of a pump, filter, filter cassettes, and SKC Cyclone for the respirable fraction. Attendance times for workers at each work location were registered via thorough observations made by the research team. Results: The logbook method for exposure estimation based on stationary sampling equipment made it possible to calculate UFP exposure for workers operating the furnaces at a ferrosilicon plant. The mid-size furnace and the large furnace were evaluated separately. The workers operating the largest furnace were exposed to 1.47 × 104 particles/cm3, while workers operating the mid-size furnace were exposed to 2.06 × 104 particles/cm3, with a mean of 1.74 × 104 particles/cm3. Substantial contributions from the casting area, ladle transport corridor, and both tapping areas were made. Exposure to respirable particles was 2.04 mg/m3 (logbook); 2.26 mg/m3 (personal sampling) for workers operating the large-sized furnace, 3.24 mg/m3 (logbook); 2.44 mg/m3 (personal sampling) for workers operating the medium-sized furnace, and 2.57 mg/m3 (logbook); 2.53 mg/m3(personal sampling) on average of all tappers. The average ratio of these two methods’ results was 1.02, which indicates that the logbook method could be used as a substitute for personal sampling when it is not possible to perform personal sampling, at least within this industry. Conclusions: The logbook method is a useful supplement for exposure assessment of UFP, able to identify the most polluted areas of the workplace and the contribution of different work tasks to the total exposure of workers, enabling companies to take action to reduce exposure.

One-year follow-up of microbial diversity in bioaerosols emitted in a waste sorting plant in France

Bioaerosols emitted in waste sorting plants (WSP) can induce some adverse health effects on the workers such as rhinitis, asthma and hypersensitivity pneumonitis. The composition of these bioaerosols is scarcely known and most of the time assessed using culture-dependent methods. Due to the well-known limitations of cultural methods, these biodiversity measurements underestimate the actual microbial taxon richness. The aim of the study was to assess the airborne microbial biodiversity by using a sequencing method in a French waste sorting plant (WSP) for one year and to investigate the main factors of variability of this biodiversity. Static sampling was performed in five areas in the plant and compared to an indoor reference (IR), using closed-face cassettes (10 L.min−1) with polycarbonate membranes, every month for one year. Environmental data was measured (temperature, relative humidity). After DNA extraction, microbial biodiversity was assessed by means of sequencing. Bacterial genera Staphylococcus, Streptococcus, Prevotella, Lactococcus, Lactobacillus, Pseudomonas and fungal genera Wallemia, Cladosporium, Debaryomyces, Penicillium, Alternaria were the most predominant airborne microorganisms. Microbial biodiversity was different in the plant compared to the IR and seemed to be influenced by the season.

In-situ and ex-situ measurement of hydrophobic organic contaminants in soil air based on passive sampling: PAH exchange kinetics, non-equilibrium correction and comparison with traditional estimations

It is a great challenge to accurately estimate chemical activity of hydrophobic organic contaminants in field soils. Ex-situ and in-situ determinations were developed for this purpose based on low-density polyethylene (LDPE) passive sampling and non-equilibrium correction by release of performance reference compounds (PRCs) previously spiked to the samplers. This work investigated kinetic processes of target contaminants’ uptake into and PRCs’ release from the sampler in an ex-situ soil suspension incubated for 100 days. A close agreement of kinetic parameters for pyrene’s (target) uptake into and deuterated pyrene’s (PRC) release from LDPE indicated their similar exchange kinetics. Three kinetic models were developed to correct uptake of target compounds in non-equilibrium conditions via release processes of PRCs. The second-order kinetic model was recommended for ex-situ measurements. The PRC-based non-equilibrium corrections were further applied to in-situ static passive sampling from several weeks to months in a PAH-contaminated field site. Two-weeks’ deployments were sufficient for quantifying lighter PAHs (logKOA < 8.0), but not recommended to accurately estimate heavier PAHs (logKOA > 9.0), even if over four months. Concentration estimates from the in-situ and ex-situ passive samplings were comparable in order of magnitude with traditional estimation from equilibrium partitioning models considering both organic and black carbon fractions.

Reduction in lead exposures with lead-free ammunition in an advanced urban assault course

The training of soldiers for urban conflict involves marksmanship instruction on outdoor flat ranges and the teaching of close-quarter battle techniques in indoor facilities, referred to as shoot houses, where intense firing exercises can generate high air lead levels from small arms ammunition, flash bang grenades, and explosive devices. Levels of lead and copper in air were evaluated during five training activities of a 45-day training course using both stationary general area and breathing zone sampling over a 2-year period. Individual blood lead values were determined prior to and at course completion. Mean breathing zone lead concentrations for the five training activities ranged from 0.014 on the outdoor flat range to 0.064 mg/m3 inside shoot houses; with a change to lead-free ammunition the values were reduced to a range of 0.006–0.022 mg/m3. Isolated flash bang grenades generated very high general area lead concentrations (2.0 mg/m3), which in training were associated with the highest measured breathing zone concentration (0.16 mg/m3). For copper, mean breathing zone concentrations increased from 0.010 to 0.037 mg/m3 with the change to lead-free frangible ammunition on the outdoor range, but remained below the permissible exposure limit for copper fume. Inside shoot houses, mean breathing zone copper concentrations exceeded the permissible exposure limit with ball and lead-free frangible ammunition, ranging from 0.077–0.13 mg/m3. With the introduction of lead-free ammunition, when comparing the blood lead differences between start and finish of the course, there was a significant reduction in the mean blood lead difference from 13.3 µg/dL to 5.4 µg/dL. Options for mitigation of potentially high exposure areas using improved ventilation designs are discussed. These results advocate for improved designs for shoot house training facilities, stress the importance of removing lead from ammunition and explosive devices for training, and promote the continued need for implementation of controls to mitigate and manage metal exposures during training.

Application of Constant Rate of Strain Tests in Consolidation Analysis of the Band-Shaped Prefabricated Vertical Drains for Vietnam Clays: The Validation Analysis

Band-shaped prefabricated vertical drains in the combination of surcharge preloading have been widely applied in the soft ground improvement cases in Vietnam to eliminate the post-construction settlement of the ground. However, the method of the settlement prediction has remained incorrect on the comparison between the field and calculation. A new procedure for consolidation analysis is proposed to determine the ground settlement more accurately in the routine design of the soft ground improvement. Two case studies are presented to study the ground performance under consolidation with surcharge preloading. The consolidation analysis of the soft ground deposits with the application of the constant rate of strain (CRS) consolidation tests is performed. In addition to that, the input parameters as the coefficient of consolidation and compression indices of the soft ground are characterized based on the CRS tests under the strain rate of 0.02%/min. on undisturbed soil samples that are taken at the two sites by stationary piston sampler. On the comparison of calculated and field monitored data of surface settlement, layered settlement, dissipation of the excess pore water pressure, and undrained strength gain, this analysis is also to confirm the appropriate strain rate for CRS tests, which are utilized in the determination of consolidation parameters.

Wastewater treatment plant workers’ exposure and methods for risk evaluation of their exposure

Work in wastewater treatment plants (WWTPs) can be associated with respiratory symptoms and diarrhea. The aim of this study was to obtain knowledge about WWTP workers' exposure to airborne bacteria and endotoxin, and the inflammatory potential (TIP) of their exposure, and to evaluate the risk posed by the exposure by 1) calculating a hazard index and relating the exposure to suggested occupational exposure limits (OELs), 2) estimating the potential deposition of bacteria in the airways, 3) relating it to the risk group classification of bacteria by the European Union, and 4) estimating the TIP of the personal exposure. A cohort of 14 workers were followed over one year. Bioaerosols were collected using personal and stationary samplers in a grid chamber house and an aeration tank area. Airborne bacteria were identified using (MALDI-TOF MS), and TIP of exposure was measured using HL-60 cells. A significant effect of season, work task, and person was found on the personal exposure. A hazard index based on exposure levels indicates that the risk caused by inhalation is low. In relation to suggested OELs, 14% and 34% of the personal exposure were exceeded for endotoxin (≥50 EU/m3) and bacteria (≥500 CFU/m3). At least 70% of the airborne bacteria in the grid chamber house and the aeration tank area could potentially deposit in the lower respiratory tract. From the personal samples, three of 131 bacterial species, Enterobacter cloacae, Staphylococcus aureus, and Yersinia enterocolitica are classified within Risk Group 2. Seven additional bacteria from the stationary samples belong to Risk Group 2. The bacterial species composition was affected significantly by season (p = 0.014) and by sampling type/area (p = 0.001). The TIP of WWTP workers’ exposure was higher than of a reference sample, and the highest TIP was measured in autumn. TIP of personal exposure correlated with bacterial exposure. Based on the geometric average exposures to endotoxin (9.2 EU/m3) and bacteria (299 CFU/m3) and based on the calculated hazard index, the risk associated with exposure is low. However, since 43 of 106 exposure levels exceed suggested OELs, the TIP of exposure was elevated and associated with bacterial exposure, and WWTP workers were exposed to pathogenic bacteria, a continued focus on preventive measures is important. The identification of bacteria to species level in personal samples was necessary in the risk assessment, and measurement of the microbial composition made the source tracking possible.

Optimization and comparison of headspace hot injection and trapping, headspace solid-phase microextraction, and static headspace sampling techniques with gas chromatography–mass spectrometry for the analysis of volatile compounds in kimchi

The identification of volatile compounds (VCs) related to flavors is important for confirming food quality, and instrumental techniques are required to effectively and accurately identify and determine the VCs responsible for such flavors. The VCs related to kimchi flavor were analyzed by headspace hot injection and trapping (HS-HIT), which is a type of multiple headspace sample enrichment sampling technique. For the HS-HIT sampling technique, the cool injection system temperature was optimized to −40 °C and the multiple sampling frequency was optimized to nine injections. Moreover, HS-HIT was compared with static headspace (SHS) and headspace solid-phase microextraction (HS-SPME) sampling techniques for the VC analysis of kimchi. The overall peak intensities in the total ion chromatograms (TICs) with SHS and HS-SPME were lower than with HS-HIT. Although the HS-HIT sampling technique was complementary to the HS-SPME sampling technique for VC analysis, it allowed more sulfur compounds characteristic of kimchi to be identified than the SHS and HS-SPME sampling techniques. Therefore, we recommend the use of the HS-HIT sampling technique with GC-MS for identifying the VCs associated with kimchi flavor. This study confirmed the usefulness of the HS-HIT sampling technique for the analysis of VCs.

The application research of solid‐phase extraction and headspace gas chromatography in the detection of methanol in transformer oil

Methanol in transformer oil has been recently proposed as new marker of the aging of solid insulation in power transformers. Because the concentration of methanol in transformer oil is usually less than 500 µg/l and even less than 50 µg/l that cannot be detected by common methods. This paper combined static headspace sampling and solid‐phase extraction (SPE) as pretreatment, used SPE to adsorb and concentrate sample, headspace sampling to desorb and inject methanol in to the gas chromatography. The experiments show that it will achieve the optimal performance when headspace conditions were the equilibrium temperature of 90°C and the equilibrium time of 25 min. The linear relation between the concentration of methanol and the peak area was satisfying in the concentration range from 10 to 600 µg/l with goodness of fit of 0.997. In addition, this method can be applied in practical work. © 2020 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

Uranium Aerosol Activity Size Distributions at a Nuclear Fuel Fabrication Plant.

Inhalation of uranium aerosols is a concern in nuclear fuel fabrication. Determination of committed effective doses and lung equivalent doses following inhalation intake requires knowledge about aerosol characteristics; e.g., the activity median aerodynamic diameter (AMAD). Cascade impactor sampling of uranium aerosols in the breathing zone of nuclear operators was carried out at a nuclear fuel fabrication plant producing uranium dioxide via ammonium uranyl carbonate. Complementary static sampling was carried out at key process steps. Uranium on impaction substrates was measured using gross alpha counting and alpha spectrometry. Activity size distributions were evaluated for both unimodal and bimodal distributions. When a unimodal distribution was assumed, the average AMAD in the operator breathing zone at the workshops was 12.9–19.3 μm, which is larger than found in previous studies. Certain sampling occasions showed variable isotope ratios (234U/238U) at different impactor stages, indicating more than one population of particles; i.e., a multimodal activity size distribution. When a bimodal distribution (coarse and fine fraction) was assumed, 75–88% of the activity was associated with an AMAD of 15.2–18.9 μm (coarse fraction). Quantification of the AMAD of the fine fraction was associated with large uncertainties. Values of 1.7–7.1 μm were obtained. Static sampling at key process steps in the workshops showed AMADs of 4.9–17.2 μm, generally lower than obtained by breathing zone sampling, when a unimodal distribution was assumed. When a bimodal distribution was assumed, a smaller fraction of the activity was associated with the coarse fraction compared to breathing zone sampling. This might be due to impactor positioning during sampling and sedimentation of large particles. The average committed effective dose coefficient for breathing zone sampling and a bimodal distribution was 1.6–2.6 μSv Bq−1 for 234U when Type M/S absorption parameters were assumed (5.0 μSv Bq−1 for an AMAD of 5 μm). The corresponding lung equivalent dose coefficient was 3.6–10.7 μSv Bq−1 (29.9 μSv Bq−1 for an AMAD of 5 μm). The predicted urinary excretion level 100 d after inhalation intake was found to be 13-34% of that corresponding to an AMAD of 5 μm. Uranium aerosols generated at a nuclear fuel fabrication plant using ammonium uranyl carbonate route of conversion were associated with larger AMADs compared to previous work, especially when sampling of aerosols was carried out in the operator breathing zone. A bimodal activity size distribution can be used in calculations of committed effective doses and lung equivalent doses, but parameters associated with the fine fraction must be interpreted with care due to large uncertainties.

Assessment of Worker Exposure to Occupational Organic Dust in a Hemp Processing Facility.

The cultivation and processing of industrial hemp, Cannabis sativa L., is a developing industry in Australia. Exposure to hemp dust is demonstrated as producing reactive and respiratory health effects, potentially causing permanent lung disease or damage. The aim of this study was to assess the airborne organic dust concentrations generated in an Australian hemp processing facility. Personal sampling, in the breathing zone of exposed workers was undertaken for exposure to respirable dust, along with parallel static sampling for airborne concentrations of inhalable and respirable dust fractions. Both static and personal sampling showed that respirable dust concentrations (mg m-3) exceeded the Australian Institute of Occupational Hygienists (AIOH) recommended maximum exposure limit of 1 mg m-3 (respirable fraction) for dusts not otherwise specified, with mean exposures (mg m-3) of M = 1.33, standard deviation (SD) = 1.09 (range 0.07-3.67 mg m-3) and M = 4.49, SD = 4.49 (range 0.77-11.08 mg m-3). The results of the investigation indicate that workers in the hemp processing industry are at risk of developing permanent and disabling respiratory disease due to high dust exposure. There is no Australian occupational exposure limit specifically for hemp dust. It is recommended further research is needed and industry-specific guidance material or model code of practice developed to effectively control exposures.

A new portable sampler to monitor pollen at street level in the environment of patients

Allergic rhinitis caused by pollen exposure is one of the most common allergic diseases. Therefore monitoring pollen levels in ambient air is an important tool in research and health care. Most European monitoring stations collect airborne pollen at rooftop levels for measurements in the larger surrounding of the sampling station, and not in the direct environment of sensitized subjects. Here we present the development and evaluation of a portable pollen sampler, called “Pollensniffer”, that was designed to collect pollen in the immediate environment of allergic subjects. Validation of the Pollensniffer against the standard volumetric pollen sampler showed for most pollen types high correlations between the number of pollen collected by those two devices (Spearman's Correlation Coefficient > 0.8); the Pollensniffer appeared to collect on average 5.8 times more pollen per hour than the static sampler. Pollen monitoring was performed using this Pollensniffer at street level at 3 different locations in the city of Leiden during 22 weeks in 2017 and 21 weeks in 2018, during three 15-min periods a day and at one day in the week. The results showed that the pollen levels for birch and grass pollen can significantly differ from location to location and per time of day. Furthermore, the Pollensniffer measurements at street level showed that birch and grass pollen grains were detected 1 1/2 and 2–3 weeks, respectively, before detection at rooftop level. The street measurements show that allergic subjects can encounter varying pollen levels throughout the city and that they can be exposed to grass and birch pollen and may experience hay fever symptoms, even before the sampler at rooftop level registers these pollen.