Sample Of Persons Research Articles

Semi-Supervised Person Detection in Aerial Images with Instance Segmentation and Maximum Mean Discrepancy Distance

Detecting sparse, small, lost persons with only a few pixels in high-resolution aerial images was, is, and remains an important and difficult mission, in which a vital role is played by accurate monitoring and intelligent co-rescuing for the search and rescue (SaR) system. However, many problems have not been effectively solved in existing remote-vision-based SaR systems, such as the shortage of person samples in SaR scenarios and the low tolerance of small objects for bounding boxes. To address these issues, a copy-paste mechanism (ISCP) with semi-supervised object detection (SSOD) via instance segmentation and maximum mean discrepancy distance is proposed (MMD), which can provide highly robust, multi-task, and efficient aerial-based person detection for the prototype SaR system. Specifically, numerous pseudo-labels are obtained by accurately segmenting the instances of synthetic ISCP samples to obtain their boundaries. The SSOD trainer then uses soft weights to balance the prediction entropy of the loss function between the ground truth and unreliable labels. Moreover, a novel evaluation metric MMD for anchor-based detectors is proposed to elegantly compute the IoU of the bounding boxes. Extensive experiments and ablation studies on Heridal and optimized public datasets demonstrate that our approach is effective and achieves state-of-the-art person detection performance in aerial images.

A pilot study of occupational exposure to ultrafine particles during 3D printing in research laboratories.

3D printing is increasingly present in research environments, and could pose health risks to users due to air pollution and particulate emissions. We evaluated the nanoparticulate emissions of two different 3D printers, utilizing either fused filament fabrication with polylactic acid, or stereolithography (SLA) with light curing resin. Nanoparticulate emissions were evaluated in two different research environments, both by environmental measurements in the laboratory and by personal sampling. The SLA printer had higher nanoparticulate emissions, with an average concentration of 4,091 parts/cm3, versus 2,203 particles/cm3 for the fused filament fabrication printer. The collected particulate matter had variable morphology and elemental composition with a preponderance of carbon, sulfur and oxygen, the main byproducts. Our study implies that when considering the health risks of particulate emissions from 3D printing in research laboratories, attention should be given to the materials used and the type of 3D printer.

Personal measurements and sampling of particulate matter in a subway – Identification of hot-spots, spatio-temporal variability and sources of pollutants

A mobile measurement system for complex characterization of particulate matter (PM) was developed together with the proposed methodology and applied in the subway system of Munich, Germany. The main objectives were to observe the spatio-temporal variability of PM, personal exposure, identify hot-spots and pollution sources. Particle mass (PMx) and number (PNC) concentrations, and equivalent black carbon (eBC) were measured at 0.1–1 Hz. On the U5 subway line, PM10, PM2.5 and PM1 concentrations at platforms ranged from 59 to 220, 27–80, and 9–21 μg m−3, respectively. During rides towards downtown, average PM10, PM2.5 and PM1 levels gradually increased from 8 to 220, 2 to 71 and 2–20 μg m−3, respectively, with a similar dynamic of decrease on the return journey. Spatial variability of PM was generally more important than temporal, and significant differences were observed between platforms. During the rides, air exchange between train and tunnel was high in both air-conditioned and old passively ventilated trains. Peak PM concentrations on platforms were associated with arriving/departing trains. Subway PNC were not significantly elevated, but a few cases of intake of traffic-related particles from outside were observed, otherwise air exchange was considered low. Generally, most of the aerosol mass was composed of iron corrosion products from rails and wheels (Fe up to 66 μg m−3 in PM2.5). The effective density of PM2.5 was 2.1 g cm−3. Particles were classified as 75.4% iron oxides, 5.35% metallic Fe, 1.23% aluminosilicates and 17% carbon and oxygen rich particles. The iron oxide particles consisted predominantly of Fe (63.4 ± 8.7 wt%) and O (36.2 ± 8.2 wt%). To effectively monitor subway PM and reduce overall PM exposure, we propose to identify hot-spots using our methodology and focus on improving their ventilation, as well as installing filters in air-conditioned wagons.

Lean Practices, Perceived Environmental Uncertainty, and Business Performance: a Quantitative Study of Smes in Thailand

Purpose: The objective of this study was to investigate the moderating role of environmental uncertainty (EU) on the relationship between lean practices (LP) and business performance (BP) in SMEs in Thailand. Design/methodology/approach: The 170 samples of middle management level persons who were aware of lean concepts or practices from 120 manufacturing companies of SMEs in Thailand. We analyzed the relationship between lean practices and business performance by multiple linear regression analysis (MLR). Findings: The results revealed that performance uncertainty and process uncertainty have a significant impact on lean practices with a direct and negative effect. For the key performance result, the results revealed that only Statistical Process Control (SPC) and employee involvement (EI) of lean practices have a significant impact on the key performance result with a direct and positive significantly impactful, the results revealed that only Just in Time or JIT and Statistical Process Control (SPC) have a significant impact on the customer result control direct and positive effect. For the employee result, the results revealed that four dimensions of Lean Practices including supplier development or SD, Setup Time Reduction (STR), employee involvement, and Total Productive Maintenance (TPM) have a significant impact on the employee result with direct and positive effect. Research, Practical & Social Implications: This study provides lean practices in SMEs in Thailand and their moderating role on environmental uncertainty on the relationship between lean practices and business performance which in contributes to economic Thailand. Further research should focus on specific industries. Originality/value: Research moderating role of environmental uncertainty (EU) on the relationship between lean practices (LP) and business performance (BP) in SMEs in Thailand are especially important in SMEs.

Development and Internal Validation of Case Definitions for Prevalence Estimation of Microvascular Complications of Diabetes in Routine Data

Surveillance of diabetes requires up-to-date information on the prevalence of diabetes and its complications over time. For this purpose, statutory health insurance (SHI) data is being increasingly used, as the data is available in a timely fashion and case numbers enable detailed estimates also of diabetes complications. The aim of the present study was the development and internal validation of case definitions for the prevalence estimation of diabetic retinopathy (DRP), diabetic polyneuropathy (DPN) and diabetic foot syndrome (DFS). Persons with diabetes differentiated by type 1, type 2, and other diabetes in an age- and sex-stratified sample of persons insured by Barmer SHI in 2018 (n=72,744) comprised the study popuation. Based on the central ICD codes for microvascular complications (DRP: H36.0; DPN: G63.2; DFS: E1X.74/.75), case definitions were developed including additional ICD codes for complications without direct diabetes reference. Subsequently, the case definitions were internally validated. For the validation, coding in the inpatient setting (m1S) or repeatedly in the outpatient setting (m2Q) as well as coding of specific procedures (EBM, OPS) and drug prescriptions or by relevant specialists were considered. Additionally, we analysed the documentation of the diagnoses in the previous years. In 2018, the prevalence of the central ICD codes was 8.4% for DRP (H36.0), 18.9% for DPN (G63.2) and 13.4% for DFS (E1X.74/.75). After inclusion of additional ICD codes in the case definition, prevalence increased significantly for DRP (9.6%) and DPN (20.7%), and barely for DFS (13.5%). Internal validation confirmed the majority of diagnoses (DRP: 96.7%; DPN: 96.5% DFS: 95.8%) and m2Q represented the most relevant criterion. When up to four previous years were considered, prevalences were up to 30% higher for DPN and DFS and up to 64% higher for DRP. The inclusion of additional ICD codes in the case definition of microvascular complications of diabetes appears meaningful, as this increases the sensitivity of the prevalence estimate. Internal validation suggests that the documented diagnoses are plausible. However, not all diagnoses are documented annually, leading to an underestimation of the prevalence using a cross-sectional study design of one year.

Agreement between telerehabilitation and face-to-face orofacial myofunctional assessment in persons with acquired brain injury

ABSTRACT Background and objective Orofacial myofunctional disorders are common in persons with acquired brain injury. A new way for early detection of orofacial myofunctional disorders via information and communication technologies may improve accessibility. The purpose of this study was to evaluate the level of agreement between face-to-face and tele-assessment of an orofacial myofunctional protocol in a sample of persons with acquired brain injury. Methods A masked comparative evaluation was conducted in a local association of patients with acquired brain injury. Twenty-three participants (39.1% female, mean age of 54 years) with a diagnosis of acquired brain injury were included in the study. The patients followed a face-to-face and a real-time online assessment using the Orofacial Myofunctional Evaluation with Scores protocol. This is a protocol for evaluation with numerical scales that assess the physical characteristics and the main orofacial functions of patients including appearance, posture, and mobility of lips, tongue, cheeks, and jaws, respiration, mastication, and deglutition. Results The analysis showed excellent interrater reliability (ρ ≥ 0.85) for all the categories. In addition, most confidence intervals were narrow. Conclusions This study reveals excellent interrater reliability of an orofacial myofunctional tele-assessment in patients with acquired brain injury in comparison with a traditional face-to-face evaluation.

Eye and airway symptoms in hospital staff exposed to a product containing hydrogen peroxide, peracetic acid, and acetic acid.

Sporicidal products containing hydrogen peroxide (HP),peracetic acid (PAA),and acetic acid (AA)are used widely in multiple industries, including healthcare. Despite widespread use in healthcare, few studies have assessed associations between exposures to HP, PAA, and AA, and work-related symptoms in these settings. In 2018, we performed a health and exposure assessment at a hospital where a sporicidal product consisting of HP, PAA, and AA, was used as the primary cleaner on hospital surfaces. We collected 56 personal and mobile air samples for HP, PAA, and AA on participants while they performed their regular cleaning duties; collected area samples for HP (n = 28), PAA (n = 28), and AA (n = 70) in multiple hospital locations where cleaning was performed; and administered a postshift survey to assess eye, skin, and upper and lower airway symptoms that occurred cross-shift or in the previous 4 weeks. Full-shift exposure levels for HP (range: <3-559 ppb), PAA (range: <0.2-8 ppb), and AA (range: <5-915 ppb) were all below USoccupational exposure limits. We observed positive associations (p < 0.05) between shift, departmental average, and departmental 95th percentile exposures to HP, PAA, and AA vapors, and work-related acute (cross-shift) and chronic (previous 4 weeks) eye, upper airway, and lower airway symptoms after adjusting for age, gender, smoking status, use of other cleaning products containing sensitizers and irritants, allergic status, and stress. Our observations of work-related upper and lower airway symptoms among hospital workers exposed to vapors from a sporicidal product containing HP, PAA, and AA indicate a need for a combination of engineering, administrative, and PPE controls to reduce exposure. Additionally, alternative nonchemical disinfection technologies should be further investigated as a means to simultaneously reduce healthcare workers' exposure to disinfectants while also minimizing costly healthcare-acquired infections.

Adequacy of stationary measurements as proxies for residential personal exposure to gaseous and particle air pollutants

People are exposed to myriad of airborne pollutants in their homes. Owing to diverse potential sources of air pollution and human activity patterns, accurate assessment of residential exposures is complex. In this study, we explored the relationship between personal and stationary air pollutant measurements in residences of 37 participants working from home during the heating season. Stationary environmental monitors (SEMs) were located in the bedroom, living room or home office and personal exposure monitors (PEMs) were worn by the participants. SEMs and PEMs included both real-time sensors and passive samplers. During three consecutive weekdays, continuous data were obtained for particle number concentration (size range 0.3–10 μm), carbon dioxide (CO2), and total volatile organic compounds (TVOC), while passive samplers collected integrated measures of 36 volatile organic compounds (VOCs) and semi volatile organic compounds (SVOCs). The personal cloud effect was detected in >80% of the participants for CO2 and >50% participants for PM10. Multiple linear regression analysis showed that a single CO2 monitor placed in the bedroom efficiently represented personal exposure to CO2 (R2 = 0.90) and moderately so for PM10 (R2 = 0.55). Adding a second or third sensor in a residence did not lead to improved exposure estimates for CO2, with only 6–9% improvement for particles. Selecting data from SEMs when participants were in the same room improved personal exposure estimates by 33% for CO2 and 5% for particles. Out of 36 detected VOCs and SVOCs, 13 had at least 50% higher concentrations in personal versus stationary samples. Findings from this study aid improved understanding of the complex dynamics of gaseous and particle pollutants and their sources in residences, and could support the development of refined procedures for residential air quality monitoring and inhalation exposure assessment.

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

Changes in movement characteristics in response to private and social information acquisition of socially foraging fish

To overcome the cost of competition resulting from foraging socially, individuals may balance their use of private (i.e. acquired from personal sampling) and social (i.e. acquired by watching other individuals) information to adjust their foraging strategy accordingly. Reliability of private information about environmental characteristics, such as the spatial distribution of prey, is thus likely to affect individual movement and social interactions. We aimed to investigate how movement characteristics of foraging individuals changed as they acquired reliable information about the spatial occurrence of prey in a foraging context. We allowed guppies, Poecilia reticulata, to develop the reliability of their private knowledge about prey spatial occurrence by repeatedly testing shoals in a foraging task under three experimental distributions of prey: (1) aggregated prey forming three patches located in fixed locations, (2) scattered distribution of prey with random locations, or (3) no prey (used as a control). Using individual time series of spatial coordinates, we computed a suite of movement variables reflecting search effort, social proximity and locomotion characteristics during foraging, to examine changes occurring over repeated trials. Over time, individuals foraging on either scattered or aggregated prey travelled greater distances, showed an increasing distance to their closest neighbour and became slightly more stochastic in their acceleration profile, compared to control individuals. We found that behaviour changed as private information increased over time, with a clear behavioural shift and an increase of collective foraging efficiency occurring on the third testing day. Social proximity was the major predictor of foraging success in the absence of prior foraging information, while search effort became the most important predictor of foraging success as information increased. In conclusion, we showed that individuals' movement patterns changed as they acquired private information. Contrary to our predictions, the spatial distribution of prey did not affect any of the movement variables of interest.

Exposure levels of dust, endotoxin, and microorganisms in the Danish recycling industry.

Recycling of domestic waste and a number of employees in the recycling industry is expected to increase. This study aims to quantify current exposure levels of inhalable dust, endotoxin, and microorganisms and to identify determinants of exposure among recycling workers. This cross-sectional study included 170 full-shift measurements from 88 production workers and 14 administrative workers from 12 recycling companies in Denmark. The companies recycle domestic waste (sorting, shredding, and extracting materials from waste). We collected inhalable dust with personal samplers that were analysed for endotoxin (n = 170) and microorganisms (n = 101). Exposure levels of inhalable dust, endotoxin, and microorganisms and potential determinants of exposure were explored by mixed-effects models. The production workers were 7-fold or higher exposed to inhalable dust, endotoxin, bacteria, and fungi than the administrative workers. Among production workers recycling domestic waste, the geometric mean exposure level was 0.6 mg/m3 for inhalable dust, 10.7 endotoxin unit (EU)/m3 for endotoxin, 1.6 × 104 colony forming units (CFU)/m³ of bacteria, 4.4 × 104 CFU/m³ of fungi (25 °C), and 1.0 × 103 CFU/m³ of fungi (37 °C). Workers handling paper or cardboard had higher exposure levels than workers handling other waste fractions. The temperature did not affect exposure levels, although there was a tendency toward increased exposure to bacteria and fungi with higher temperatures. For inhalable dust and endotoxin, exposure levels during outdoor work were low compared to indoor work. For bacteria and fungi, indoor ventilation decreased exposure. The work task, waste fraction, temperature, location, mechanical ventilation, and the company size explained around half of the variance of levels of inhalable dust, endotoxin, bacteria, and fungi. The production workers of the Danish recycling industry participating in this study had higher exposure levels of inhalable dust, endotoxin, bacteria, and fungi than the administrative workers. Exposure levels of inhalable dust and endotoxin among recycling workers in Denmark were generally below established or suggested occupational exposure limits (OEL). However, 43% to 58% of the individual measurements of bacteria and fungi were above the suggested OEL. The waste fraction was the most influential determinant for exposure, and the highest exposure levels were seen during handling paper or cardboard. Future studies should examine the relationship between exposure levels and health effects among workers recycling domestic waste.

The association between social functioning and health literacy among rural Southeastern African Americans with hypertension.

African Americans living in low socioeconomic circumstances are at high risk of poor health outcomes; this is particularly true for those with hypertension. Many African Americans with chronic hypertension living in the rural impoverished Southeastern USA have low health literacy and are socially isolated. These factors are known to have a negative impact on health outcomes, but it is possible that social support may overcome some of the effect of low health literacy. Since little has been reported about this association, we examined the association between social functioning and health literacy in a rural African American population in the Southeast USA. We used baseline data from participants in the Southeastern Collaboration to Improve Blood Pressure Control, a pragmatic trial that recruited rural African Americans with persistently uncontrolled hypertension and collected survey data. Overall, 33.5% of the 1221 person sample reported social isolation, 26.0% reported low instrumental support, 36.0% reported low emotional support, and 63.4% had inadequate health literacy. All three domains of low social functioning were significantly associated with low health literacy, and this effect was robust to multivariable adjustment for sociodemographics and cognitive functioning for social isolation (adjusted odds ratio 1.62, 95% confidence intervals 1.20-2.20). In conclusion, the majority of this sample living in the NC and AL Black Belt had high social functioning but inadequate health literacy. Tests of interventions to improve social support, especially social isolation, may be warranted to overcome low health literacy in this high-risk rural population.

Intersectional Discrimination in HIV Healthcare Settings Among Persons with Diagnosed HIV in the United States, Medical Monitoring Project, 2018-2019.

Experiences with stigma and discrimination in healthcare settings are associated with negative health outcome for persons with HIV (PWH). PWH may experience discrimination due to the intersection of multiple marginalized social identities. Describing these experiences is important for informing interventions and strategies to reduce stigma and discrimination. We report experiences with discrimination in HIV healthcare settings attributed to multiple characteristics, e.g., sexual orientation, race/ethnicity, income, or social class, and/or injection drug use, among a nationally representative sample of persons with diagnosed HIV in the United States using data from the Medical Monitoring Project (MMP). We calculated weighted prevalences and associated 95% confidence intervals for any discrimination and discrimination attributed to multiple characteristics (intersectional discrimination). Among those experiencing discrimination, nearly 1 in 4 persons reported intersectional discrimination, with a higher burden among key populations of focus for HIV prevention and treatment. Discrimination was attributed to HIV status (62.5%), sexual orientation (60.4%), and race/ethnicity (54.3%). Persons who experienced intersectional discrimination were less likely to have a regular HIV care provider, have trust in HIV care or treatment information from healthcare providers, and be antiretroviral treatment or HIV care visit adherent. Future studies should explore methods to operationalize and assess experiences with intersectional stigma and discrimination and use the outcomes to inform qualitative research that provides more context and a deeper understanding of experiences with intersectional discrimination among PWH.

85 Workers’ Exposure to Respirable and Inhalable Particles During Filling of Containers with Bulk Material and Efficacy of Protective Measures

Abstract Containers are filled with bulk material in many enterprises. To assess workers´ exposure to respirable and inhalable particles we have performed workplace measurements in ten enterprises. Beside personal air sampling stationary samplers were used in the filling zone at the exhaust ventilation and in the work area. Additionally, the PIMEX system with a direct reading light scattering photometer was used for visualisation of exposure. Workers filled containers with automatic and semi-automatic filling stations or manually using hand shovels. For all solids the dustiness for boths particle fraction has been determined using the continuous drop method (EN 15051). The estimated dustiness for both particle fractions shows a good correlation for their conversion using an exponential function. The results were splitted into two similar exposure groups: manual filling and semi-automatic/automatic filling. For personal air sampling, no correlation was found between airborne concentration of the respirable particle fraction and the corresponding dustiness. On the other hand, the measurement results for the inhalable particle fraction and dustiness correlate well for both SEGs. Therefore, the exposure potential may be categorised using dustiness of the inhalable particle fraction. Furthermore, for conversion of inhalable to respirable particle fraction a power function proved to be most suitable. This conversion is much better suited for more standardised activities such as automatic/semi-automatic filling compared to manual filling where workers´ individual behaviour is determining their exposure. Nine video clips have been produced showing the efficacy of protective measures. For visualisation, the videos are superimposed by signals of a light scattering photometer.

134 Occupational Exposure to Different Microbial Species and Endotoxin and Serum Levels of Markers of Inflammation – Across Working Environments

Abstract Occupational exposure to bioaerosols (fungi, bacteria, and endotoxin) may be associated with early signs of health effects of the airways measured as elevated levels of inflammatory markers in serum samples. The aim of this study is to obtain knowledge about the contribution of endotoxin, different fungal and bacterial species, and dust to the inflammatory potential of bioaerosols from different working environments. Using personal samplers, bioaerosols were sampled in the inhalation zone of workers in different occupational settings. Fungal and bacterial species were identified to species level using MALDI-TOF MS. The ability of workers’ exposure to induce production of reactive oxidative species was analysed in a human cell line. Levels of the inflammatory markers C-reactive protein and serum amyloid A were measured in blood samples of the workers. The fungal and bacterial composition as well as species richness and endotoxin exposure level differed between working environments. Among the dominating microorganisms were different Staphylococcus species (work with animals), Stenotrophomonas maltophilia (work with plants), and Aspergillus niger (work with waste). While pigeon house dust was cytotoxic, pig farm dust was highly inflammogenic. The biofilm forming capacity of the exposure correlated with bacterial concentration in high exposure samples. Serum levels of inflammatory markers were associated significantly with occupational exposure to endotoxin for work with plants and waste water. As the next step, we are analysing whether this association is also found for work in other environments and whether it is associated with exposure to different microorganisms.

114 Development of High Volume Personal Aerosol Samplers

Abstract The tendency for decreasing a series of occupational exposure limit values is seen the last years. Especially metal species are linked to a larger health effect in latest toxicological assessments. These changes imply further reductions of the limits of quantification for both the sampling and analysis methods. The personal sampling methods (as a set of sampler, filter and pump) used today comprise air flows up to 10 l/min. In order to achieve higher amounts of sampled aerosols an airflow of 20 l/min is aimed for a new set of samplers for the inhalable and respirable dust fraction. This also enables shorter sampling times than a full shift, e.g. task based exposure assessment. A small set of prototypes was designed to go into testing. A filter size of 47 mm was chosen to realise a higher dust load and an acceptable pressure drop for a personal air sampling pump. Such a pump was recently developed and is now available. Samplers for the inhalable fraction with different numbers and orientation of orifices are tested in a calm air dust chamber and a wind tunnel according to the test standard EN 13205 in the particle size range up to 100 µm. A cyclone design according to the GK family of cyclones (Mesalabs) was chosen to meet the respirable convention. First test results will be shown, either in comparison with validated samplers or in terms of the sampling efficiency in dependence of the aerodynamic diameter.

32 Changes in Exposure and Related Health Effects After Preventive Actions at Black Steel Welding Environments

Abstract Welding fume constitutes a source of particles and dust that effects a large number of individuals at occupational environments throughout the world. Besides being classified as a carcinogen, welding fume has potential inflammatory properties and has been linked to cardiovascular disease. To further increase the knowledge regarding potential health and inflammatory effects, workers at occupational environments with exposure to welding fume were investigated before but also after extensive preventive actions to investigate potential effects that may be pathways for cardiovascular disease. Exposure was assessed by collecting respirable dust through stationary and personal sampling at multiple occasions over the study. Dust was used for metal analysis by ICP-MS. Particle levels were assessed by using three handheld particle-counting instruments, Lighthouse 3016-IAQ (0.3-10 µm), DustTrak 8520 (0.1-10µm) and Philips Aerasense NanoTracer (10-300 nm). A total of approximately 100 individuals were screened at the beginning and end of a workweek at the beginning of the study and again after two years after the companies had introduced a wide range of preventive actions to reduce the exposure of the workforce. Participants had metals measured in both blood and urine, markers used in clinical practice for stress in different tissues were measured, lung function using spirometry was done and a set of 40 different acute inflammatory markers were measured using electrochemiluminiscence. The study adds to the growing knowledge of effects of welding fumes on human health and how preventive actions may affect this.

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

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

115 Laboratory Performances of the CIP 10 Personal Aerosol Sampler for the Collection of Submicron Particles

Abstract The CIP 10 is a personal aerosol sampler designed to sample conventional dust or specific occupational inorganic or organic substances such as crystalline silica, isocyanates or mycotoxins. It is widespread used, especially in France. Within the CIP10, the rotating cup contains a porous polyurethane foam devoted to the collection of airborne particles and rotates inside its housing at a speed close to 6700 rpm to induce a 7 or 10 L/min sampling airflow, depending on the particle-size selector. Despite several published works regarding its physical performances, no experimental data exist regarding the sampling efficiency for submicron particles. This study aimed to measure the collection efficiency of the CIP 10 for different types of foam (60 or 75 ppi, functionalized or not) and for the three selectors (inhalable, thoracic, respirable). Polydisperse particles with aerodynamic diameters between 20 nm and 10 µm were produced using various generators and different materials (DEHS, glass beads) in a specific test rig. For a given diameter, the collection efficiency was calculated by comparing the number concentrations measured alternatively upstream and downstream of the rotating cup, using APS (TSI 3321) or SMPS (Grimm DMA Vienna Type, CPC 5.403) spectrometers. While collection efficiency was 100% for particles &amp;gt; 3 µm, it progressively decreased to around 50 % and even below 10 % for aerodynamic diameters of 800 mm and 150 nm, respectively. Collection efficiency was unaffected by the type of foam or sampler flow rate used. Bias maps and consequences on workers aerosol exposure assessment will be discussed.

112 Comparing Various Size Fractions Collected Using Dusttrak And Gravimetric Samples

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