Gas Exposure Research Articles

Impact of Ergonomic Posture on the Chemical Exposure of Workers in the Petroleum and Chemical Industry.

Despite a rise in automation, workers in the petroleum refining and petrochemical manufacturing industry are potentially exposed to various chemicals through inhalation while performing routine job duties. Many factors contribute to the degree of exposure experienced in this setting. The study objective was to characterize the impact of workplace conditions, anthropometric variability, and task orientation on exposure for a simulated routine operations task. A chemical exposure laboratory simulation study was designed to evaluate the dependent variable of chemical exposure level in the breathing zone for methane and sulfur hexafluoride. The independent variables were (i) posture of the worker, (ii) worker anthropometry, (iii) process configuration, and (iv) gas density. Pipe height was a significant predictor of gas concentration measured in the breathing zone when located in a position that encouraged the gas to enter the breathing zone of the worker. Worker anthropometry had a major impact; tall worker's (male) chemical concentrations exceeded those of the short worker (female) for methane simulations but the opposite resulted for sulfur hexafluoride. Also, worker posture had a significant impact on gas exposure where nonneutral postures were found to have higher levels of chemical concentration. The study findings indicate that the breathing zone location is altered by posture and worker height, which changes the exposures relative to the emission source depending on the gas density of the chemicals that are present. As a result, qualitative risk assessment cannot be performed accurately without accounting for these factors. Practically, controls may need to account for worker size differences and posture adaptations.

Sensing performance of Ti/TiO2 nanosheets/Au capacitive device: Implication of resonant frequency

Frequency selective gas sensing performance of Ti/TiO2 nanosheets/Au sensor is presented in this communication. The device was tested over the frequency range of 0.05–225 kHz with peak to peak amplitude of 0.5 V at the temperature ranging from 50 to 225°C under the exposure of acetone, ethanol, and methanol. The optimum sensor response towards acetone, ethanol, and methanol was recorded to be at resonant frequencies of 0.7 kHz, 0.4 kHz, and 0.3 kHz, respectively. Resonant frequency shifts under gas exposure with respect to that in the air were correlated with the change in dielectric (εr) at the nanosheets surfaces and interfaces. Over the tested frequency range order of capacitive change was found to be methanol > ethanol > acetone. Such gas response has been correlated with the degree of polarization of the analytes at the nanosheets surfaces and edges. Equivalent circuit model correlating capacitive and resistive contribution of the nanosheets have been analysed with the help of impedance spectroscopy in complex plane. Optimum capacitive response magnitude (CRM) was found to be ∼ 199%, 252%, and 256% towards 50 ppm of acetone, ethanol, and methanol, respectively. The fastest response time and recovery time of ∼ 24/14 s, 10/3 s, and 17/11 s were recorded for acetone, ethanol, and methanol, respectively.

1-Methylcyclopropene and Ethephon Effects on 'Carabao' Mango Fruits Harvested at Different Stages of Fruit Maturity

Three experiments were conducted using three different stages of fruit maturity (100, 105, and 110 DAFI or days after flower induction) of ‘Carabao’ mangoes harvested from the same set of trees. Fruits harvested were applied with 1-MCP [(dosage:0.5 µL/L) via gas exposure for 20 hours and spraying], and ethephon (dipping at 1ml/L of H2O) applied singly or in combination. Mangoes were then stored in ambient room conditions [29.2±1.6°C, 69.88±4.0% relative humidity (RH)]. Mango fruits with 1-MCP treatment applied through gas exposure at 0.5 µL/L consistently delayed the peel color change, firmness, and weight loss of harvested fruits at 100, 105 and 110 DAFI. These fruits held its shelf life for 15 (100 DAFI), 12 (105 DAFI) and 9 (110 DAFI) days compared to control with 12, 10 and 8 days respectively. Furthermore, all treatments showed varied effects on the visual quality of fruits regardless of its maturity. It also appeared that fruits at 105 DAFI treated with ethephon alone have better taste while other organoleptic attributes, chemical properties (TSS, TTA and pH), as well as the disease incidence and severity were found to be comparable. This further proved that 1-MCP delays ripening of fruits but could not prevent disease occurrence.

A Closed Loop Feature Detection Platform for Automated Neonate Cardio‐Respiratory Measurements and Data Analysis

BackgroundSudden Infant Death Syndrome is thought to partly result from unseen brain abnormalities affecting cardio‐respiratory function, but for which no clear genetic or environmental mechanisms are known. Mouse genetic and exposure models present an opportunity to uncover molecular and environmental mechanisms. However, measuring cardio‐respiratory function in neonate mice is expensive, difficult, and inefficient. One major challenge is the time needed to carry out such measurements. The neonate autoresuscitation assay, consisting of repeated anoxic exposures followed by recovery, requires the full attention of an observer for the multi‐hour duration of a single‐subject assay, limiting throughput. To address this, we developed a closed‐loop feature detection platform for automated neonate cardio‐respiratory measurements.MethodsOur platform design consists of:1) a pneumotachograph face‐mask for precise respiratory measurements. 2) a micro‐controller automated bell‐housing gas switching system for rapid induction of respiratory challenges. 3) a micro‐computer‐based data‐acquisition system with real‐time feature detection and outputs for controlling gas exposure. 4) a data analysis suite that assists with study recordkeeping and provides a facile method to extract key outcome measures from acquired data.ResultsGas challenges are administered via the rotating bell housing system. A python program detects waveform features in real‐time, such as apnea and bradycardia. Upon apnea detection, the system switches to a rescue gas. Resumption of normal breathing and heart rate can also be detected and incorporated into criteria for automated initiation of the next anoxic exposure trial. Data is stored for later offline automated analysis using the data analysis suite.ConclusionsThe system offers a relatively inexpensive approach for automated high throughput neonate cardio‐respiratory assessment for facile screening to yield important clues in developmental pathophysiology.

Respiratory Function in a Novel Neonatal Rat Model of Early Life Oxygen Dysregulation and Subsequent Immune Challenge

Preterm infant immaturity is characterised by unstable cardiorespiratory control, with male infants exhibiting poorer clinical outcomes. Very/Extremely preterm infants are at an increased risk of infection in early life. Infections are often caused by Gram‐positive bacteria that activate inflammatory pathways. We sought to characterise respiratory function and redox status in response to early life oxygen dysregulation (intermitted hypoxia and hyperoxia) and subsequent immune challenge using gram positive bacterial proteins.This study was approved by local animal ethics committee and the national regulatory body, HPRA Ireland. On postnatal day (PND) three, Sprague Dawley litters were exposed for 10 days to either cIHH or sham conditions. Following intraperitoneal (i.p) administration of LTA+PGN or vehicle solution on PND13, animals were monitored for 3 hours using whole body plethysmography. VCO2 was measured in parallel. A separate cohort of animals were exposed to an autoresuscitation protocol which consisted of acute anoxia until primary gasp and subsequent recovery in normoxic conditions (FiO2 21%). In littermates exposed to either cIHH/Sham and subsequent LTA+PGN/vehicle administration, blood, plasma and tissue was collected post‐mortem. Blood (pH and lactate) analysis was performed, plasma cortisol concentrations were quantified, and mRNA expression of NAD(P)H Quinone Dehydrogenase 1 was quantified in the diaphragm muscle. All data were analysed using a three‐way ANOVA (factors: sex, gas, drug), n=8‐10.There was a small decrease in the ventilatory equivalent following cIHH exposure (gas P<0.05). However, there was no evidence of acid‐base disturbance. We observed increased number of sighs in cIHH treated female animals (gas x sex P<0.05). NQO1 mRNA expression was upregulated in both sexes following cIHH gas exposure (gas factor P<0.05), most evident in males. Post‐sigh apnoea duration was decreased following immune challenge in both male and female rats (P<0.05). Cortisol concentrations were upregulated in both males and females following immune challenge (drug P<0.05 and sex x drug P<0.05), with higher expression evident in males. Primary apnoea duration in response to anoxia was similar across all groups. Although total number of gasps in the 30seconds post primary apnoea was significantly increased in sham females that received LTA&PGN (gas x drug interaction P<0.05). Gasping was significantly decreased in cIHH exposed females.cIHH upregulation of the anti‐oxidant pathway likely protects against oxidative stress and inflammation. cIHH also enhanced the number of sighs, known to be important in homeostatically regulating breathing variability. Neonatal exposure to immune challenge potently increased the stress hormone cortisol and increased post‐anoxic gasping in control conditions. This research has also revealed interesting sex‐specific effects as well as interactions between neonatal oxygen dysregulation and a subsequent immune challenge that need to be explored further.

Ensemble Learning-Based Approach for Gas Detection Using an Electronic Nose in Robotic Applications.

Detecting chemical compounds using electronic noses is important in many gas sensing related applications. A gas detection system is supposed to indicate a significant event, such as the presence of new chemical compounds or a noteworthy change of concentration levels. Existing gas detection methods typically rely on prior knowledge of target analytes to prepare a dedicated, supervised learning model. However, in some scenarios, such as emergency response, not all the analytes of concern are a priori known and their presence are unlikely to be controlled. In this paper, we take a step towards addressing this issue by proposing an ensemble learning based approach (ELBA) that integrates several one-class classifiers and learns online. The proposed approach is initialized by training several one-class models using clean air only. During the sampling process, the initialized system detects the presence of chemicals, allowing to learn another one-class model and update existing models with self-labelled data. We validated the proposed approach with real-world experiments, in which a mobile robot equipped with an e-nose was remotely controlled to interact with different chemical analytes in an uncontrolled environment. We demonstrated that the ELBA algorithm not only can detect gas exposures but also recognize baseline responses under a suspect short-term sensor drift condition. Depending on the problem setups in practical applications, the present work can be easily hybridized to integrate other supervised learning models when the prior knowledge of target analytes is partially available.

Gas Sensing and Thermoelectric Properties of Hybrid Composite Films Based on PEDOT:PSS and SnO or SnO2 Nanostructures

In this work poly(3,4 ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) with ethylene glycol (EG) and SnO or SnO2 nanoparticles are mixed in a controlled way to create hybrid composites in form of thin films via spin coating. The potential applicability of these composites as gas sensors and as thermoelectric materials is tested, while insights are achieved in the comprehension of the underlying physical mechanisms. The addition of SnO in the composite promotes an enhancement in the chemoresistive response upon ethanol gas exposure at room temperature. Based on the Seebeck coefficient and Hall effect measurements, improvement of the power factor (PF) is achieved by the controlled addition of SnO nanoparticles in the composite. These results promise well for progress in the use of hybrid composites in these areas paving the way for future improvement in research on hybrid electronics, involving improved scalability and energy saving.

Thermal shock-stabilized metal catalysts on oxide hemitubes: Toward ultrasensitive chemiresistors

To achieve powerful gas sensors oxide semiconductor chemiresistors, the uniform functionalization of nanocatalysts on the desired metal oxides is considered as a key strategy. However, still, it is challenging to achieve the nanocatalysts decoration on desired oxides without deterioration of target materials. In this study, thermal-shock (rapid joule-heating method) was applied to uniformly decorate Pt nanoparticles (NPs) on the surface of carbon nanofibers (CNFs) to achieve the uniform distribution of Pt NPs on one-dimensional structures. And then, SnO2 was physically deposited on the Pt NPs loaded CNFs and continuous heat-treatment was conducted to transfer the Pt NPs to desired SnO2 porous hemitubes. Thanks to the well-distributed Pt NPs on porous SnO2 hollow structures, the Pt laoded SnO2 hemitubes showed an exceptional sensitivity (Rair/Rgas = 1500 at 5 ppm) in H2S. Also, it showed high selectivity for H2S and high stability even under continuous gas exposure, confirming its potential as an effective H2S sensor.

Factors affecting prevalence of neurological symptoms among workers at gasoline stations in Rayong Province, Thailand.

This cross-sectional study was aimed at assessing the exposure to organic solvents and the factors affecting prevalence of neurological symptoms among workers at gas stations in Rayong Province. The sample included 200 workers at gas stations, including refueling staff, cashiers, food shop, coffee shop, and convenience store employees. Interview questionnaire included general information, work history, and neurological symptoms. Urine collection devices were used to detect organic solvents metabolized in urine, including t,t-muconic acid (t,t-MA), hippulic acid (HA), mandelic acid (MA), and methylhppuric acid (MHA). The results showed that the workers’ medians (interquartile range: IQR) of the metabolized organic solvents were as follows: t,t-MA was 393.62 (244.59) μg/g Cr, HA was 0.32 (0.14) g/g Cr, MA was 0.06 (0.02) g/g Cr, and MHA was 0.40 (0.13) g/g Cr. For prevalence of neurological symptoms, top three symptoms were headache (49.0%), dizziness (42.5%), and stress/irritability (38.5%). Working at a gas station present was neurological symptoms more than in the past was 32.5%. According to the assessment of exposure to metabolized organic solvents and factors affecting the prevalence of neurological symptoms, overtime work ≥ 6 hours and HA content greater than quartiles Q3 had an effect on neurologic symptoms (OR=2.17; 95%CI=1.23–5.10 and OR=2.15; 95%CI=1.18–4.76, respectively). In summary, time spent working in gas stations and exposure to toluene organic solvents can cause neurological symptoms. It is recommended to reduce overtime or add breaks during work shifts or shift changes. In addition, workers should be away from the solvent.

Solar Energy Deployment for the Sustainable Future of Vietnam: Hybrid SWOC-FAHP-WASPAS Analysis

In recent years, solar power has developed significantly in Vietnam, making an important contribution to ensuring energy conservation and decreasing greenhouse gas exposure. Recently, Vietnam has experienced impressive growth in the solar and wind energy sectors, showing the high potential of using renewable electricity in addressing energy needs. The target of this study was to construct a fuzzy multicriteria decision-making, model including strengths-weaknesses-opportunities-challenges (SWOC) analysis, the fuzzy analytic hierarchy process (F-AHP) model, and the weighted aggregates sum product assessment (WASPAS) model, to select the location of a solar power plant in south Vietnam. The proposed fuzzy multicriteria decision-making model (MCDM) model is the first solar power plant location selection in southern Vietnam that utilizes literature reviews and expert interviews. Moreover, this is the first study to provide a case study on evaluating locations during solar power plant location selection that utilizes a combination of the SWOC, FAHP, and WASPAS models. The findings of this study provide valuable knowledge for the assessment and selection of suitable locations for renewable energy projects, including both solar power energy projects and other renewable energy projects.

Differential hydrogen sulfide production by a human cohort in response to animal- and plant-based diet interventions

Hydrogen sulfide (H2S) is a toxic end-product of microbial fermentation produced in the colon that may play a role in the pathogenesis of several diseases, including ulcerative colitis and colon cancer. However, the effect of diet interventions on intestinal burden of H2S gas exposure remains poorly understood. Determine the effect of short-term (1-week) plant- and animal-based eating patterns on exvivo fecal H2S production in healthy human volunteers. The study design was an open-label, cross-over diet study and diets were self-administered. Each participant consumed two interventional diets: 1) an animal-based, low fiber (i.e. western) diet and 2) a plant-based, high fiber diet, separated by a two-week washout period. Participants collected full stool samples at the end of each week, which were processed within 2h of collection to capture H2S production. Microfluidic qPCR (MFQPCR) was used to simultaneously quantify multiple taxonomic and functional groups involved in sulfate reduction and the fecal microbiota was characterized through high-throughput DNA sequencing. Median H2S production was higher following the animal-based diet compared to the plant-based diet (p=0.02; median difference 29ppm/g, 95% CI 16-97). However, there was substantial individual variability and 2 of 11 individuals (18%) produced more H2S on the plant-based diet. Using the top and bottom quartiles of H2S percent change between animal- and plant-based diet weeks to define responders and non-responders, significant taxonomic differences were observed between the responder and non-responder cohorts. Here we report that substrate changes associated with a 1-week plant-based diet intervention resulted in lower exvivo H2S production compared to a 1-week animal-based diet intervention in most healthy individuals. However, H2S responsiveness to diet was not uniform across the entire cohort, and potential H2S production enterotypes were characterized that may predict individualized H2S responsiveness to diet.

Functionalization of the MoS2 basal plane for activation of molecular hydrogen by Pd deposition

We investigated the effects of gaseous hydrogen exposure on the bare MoS2 and Pd-deposited MoS2 basal surfaces using ambient-pressure X-ray photoelectron spectroscopy. In the Mo 3d core-level, S 2p core-level, and valence-band photoelectron spectra of a bare MoS2 surface, little change was observed in the energy shift before and after exposure to hydrogen gas. Upon hydrogen gas exposure on the Pd-deposited MoS2 surface, each peak in the photoelectron spectra (Mo 3d, S 2p, and valence-band) shifted to a lower binding energy with 0.1 eV. When hydrogen gas was evacuated, the peak energy remained lower compared with that before hydrogen gas exposure. The Pd 3d XPS spectra changed upon hydrogen gas exposure, which can be interpreted as the adsorption of dissociated hydrogen atoms on the Pd sites. These results indicate that the dissociation of molecular hydrogen and the adsorption of atomic hydrogen occur on the Pd-deposited sites on MoS2, and thereafter hydrogen atoms spillover onto the MoS2 surface. This study shows that the activation site for the dissociation of molecular hydrogen is created on an inert MoS2 basal surface by Pd deposition. In addition, the electronic states of the MoS2 substrate have been modulated by hydrogen atoms spilled over onto the MoS2 surface.

Urban afforestation: using phytotoxicity endpoints to compare air pollution tolerance of two native Brazilian plants Aroeira (Schinus terebinthifolius) and Cuvatã (Cupania vernalis).

Urban afforestation can mitigate the effects of air pollution, but the suitability of plant species for this purpose needs to be determined according to pollution intensity and climate change. The goal of this study was to evaluate the sensitivity of different phytotoxicity endpoints using two native Brazilian plant species as models, Aroeira (Schinus terebinthifolius) and Cuvatã (Cupania vernalis). The sensitivity parameters evaluated could help in selecting the most air-pollution-tolerant plant species for use in urban afforestation programs. The two plant species were exposed, in a greenhouse, to the combustion gases of a diesel engine for 120 days, with daily intermittent gas exposure. Every 30 days, leaf injury (chlorosis and necrosis), biomass, and physiological/biochemical parameters (proteins, chlorophyll, and peroxidase enzyme activity) were evaluated for both plant species. For the two selected species, the endpoints studied can be ranked according to their sensitivity (or inversely the tolerance) to diesel oil combustion gases in the following order: peroxidase > biomass ≈ chlorophyll > protein > leaf injury. The endpoint responses of higher plants can be used to assess the suitability of particular plant species for use in urban afforestation areas with relatively intense vehicle traffic.

Effects of Ethylene Degreening on Peel Color, Physical Quality, and Chemical Content of Ambon Kuning (Musa acuminata Colla)

The natural ripening of ambon kuning, a typical banana widely consumed in Indonesia, tends to produce a non-uniform yellowish peel color of the fruits. Some degreening techniques using calcium carbide or ethepon, although improving the peel color appearance, may pose a safety risk compared to ethylene degreening, a technique using ethylene gas, a gas naturally produced by the fruit. This study aimed to determine the effect of ethylene degreening on changes in peel color, physical quality, and chemical content of ambon kuning and determine the combination of treatment that produces the best results. Taguchi design, with two levels for each of the three treatment factors (ethylene gas concentrations of 185.2 and 277.8 ppm, storage temperatures of 16±1 and 29±1 °C, and gas exposure time of 48 and 72 hours) was applied to banana samples stored in a hermetic bag in a temperature-controlled container. Grey Relational Analysis (GRA) was applied to get the best results considering multiple performance measures: peel color (measured as lightness L*-, green -a*-, and yellow b*-values), hardness of peel and pulp, total dissolved solids, total chlorophyll, and total carotenoids contents. The best results were obtained when degreening was carried out with a gas concentration of 185.2 ppm at a storage temperature of 16±1 °C for 48 hours.

Video Exposure Monitoring and Position Tracking for Evaluating Particulate and Gas Exposures in a Fully Enclosed Small Arms Firing Range.

The exposure environment in small arms firing ranges is dynamic since ventilation conditions vary in space and time and instructors continuously move around throughout the range. Understanding the impact of engineering controls and instructor behavior on the levels of particulates and gases in the breathing zone is required for providing recommendations to mitigate exposure. In this study, video exposure monitoring (VEM) and position tracking technologies were used in conjunction with real-time measurements of ultrafine particle (UFP) and carbon monoxide (CO) exposures in the breathing zone of instructors in an enclosed small arms firing range. VEM was completed using Enhanced Video Analysis of Dust Exposure 2.1 developed by the National Institute for Occupational Safety and Health. With this program, video recordings of Combat Arms instructor activity were synced with exposure data collected in real-time during small arms training. Position tracking was completed using a system by Pozyx, which uses ultra-wideband (UWB) technology. Position tracking data was aligned with real-time sensor data via time-synchronization. VEM identified that the largest peaks in UFP and CO concentrations generally occurred when instructors were close to the firing line assisting shooters during live fire and when instructors were located near the center of the range near the back wall where the air supplies transition between the Left-Hand-Side (LHS) and Right-Hand-Side (RHS). The UWB position tracking results agreed with the VEM results, confirming that peak exposures occurred when firing range instructors were near the center of the range close to the back wall where the LHS and RHS air supplies transition. Without these exposure visualization technologies, this observation could not have been made. Thus, exposure visualization is a valuable tool to identify gaps in exposure assessment, although future technologies should focus on automation to expedite analysis.

Effect of the High-Pressure Hydrogen Gas Exposure in the Silica-Filled EPDM Sealing Composites with Different Silica Content.

With the increasing interest in hydrogen energy, the stability of hydrogen storage facilities and components is emphasized. In this study, we analyzed the effect of high-pressure hydrogen gas treatment in silica-filled EPDM composites with different silica contents. In detail, cure characteristics, crosslink density, mechanical properties, and hydrogen permeation properties were investigated. Results showed that material volume, remaining hydrogen content, and mechanical properties were changed after 96.3 MPa hydrogen gas exposure. With an increase in the silica content, the crosslink density and mechanical properties increased, but hydrogen permeability was decreased. After treatment, high-silica-content composites showed lower volume change than low-silica-content composites. The crack damage due to the decompression caused a decrease in mechanical properties, but high silica content can inhibit the reduction in mechanical properties. In particular, EPDM/silica composites with a silica content of above 60 phr exhibited excellent resistance to hydrogen gas, as no change in their physical and mechanical properties was observed.

Fast-tracking of NH3 interaction with ZnO nanorods and C/ZnO hybrid nanostructures by operando spectroscopy

Fast X-ray photoemission spectroscopy has been carried out to track the interaction of ammonia gas with hybrid materials based on ZnO nanorods and nanostructured carbon. We provide, for the first time, direct evidence of gas adsorption of ammonia on nanostructured hybrid interfaces combining photoemission with transport measurements through the resistivity change upon gas exposure. This operando methodology allowed us to reconstruct the adsorption isotherms and relate the different behavior to the sample morphology at the nanoscale. While on bare ZnO nanorods, physisorption of ammonia is detected along with photon beam assisted cracking, on the nanostructured carbon the formation of amine groups is detected, without displaying any effect induced by photon beam exposure. Our results make the present experiment an operando general methodology, with the possibility to relate the transport versus dose curves (ultimately the adsorption isotherms) to a specific investigation of the gas/surface interactions.

Fluorinated Graphene Contacts and Passivation Layer for MoS2 Field Effect Transistors

AbstractRealizing a future of 2D semiconductor‐based devices requires new approaches to channel passivation and nondestructive contact engineering. Here, a facile one‐step technique is shown that simultaneously utilizes monolayer fluorinated graphene (FG) as the passivation layer and contact buffer layer to 2D semiconductor transistors. Monolayer graphene is transferred onto the MoS2, followed by fluorination by XeF2 gas exposure. Metal electrodes for source and drain are fabricated on top of FG‐covered MoS2 regions. The MoS2 transistor is perfectly passivated by insulating FG layer and, in the contacts, FG layer also acts as an efficient charge injection layer, leading to the formation of Ohmic contacts and high carrier mobility of up to 64 cm2 V−1 s−1 at room temperature. This work shows a novel strategy for simultaneous fabrication of passivation layer and low‐resistance contacts by using ultrathin functionalized graphene, which has applications for high performance 2D semiconductor integrated electronics.

Drift in a popular metal oxide sensor dataset reveals limitations for gas classification benchmarks

Metal oxide (MOx) gas sensors are a popular choice for many applications, due to their tunable sensitivity, space efficiency and low cost. Publicly available sensor datasets are particularly valuable for the research community as they accelerate the development and evaluation of novel algorithms for gas sensor data analysis. A dataset published in 2013 by Vergara and colleagues contains recordings from MOx gas sensor arrays in a wind tunnel. It has since become a standard benchmark in the field. Here we report a latent property of this dataset that limits its suitability for gas classification studies. Measurement timestamps show that gases were recorded in separate, temporally clustered batches. Sensor baseline response before gas exposure were strongly correlated with the recording batch, to the extent that baseline response was largely sufficient to infer the gas used in a given trial. Zero-offset baseline compensation did not resolve the issue, since residual short-term drift still contained enough information for gas/trial identification using a machine learning classifier. A subset of the data recorded within a short period of time was minimally affected by drift and suitable for gas classification benchmarking after offset-compensation, but with much reduced classification performance compared to the full dataset. We found 18 publications where this dataset was used without precautions against the circumstances we describe, thus potentially overestimating the accuracy of gas classification algorithms. These observations highlight potential pitfalls in using previously recorded gas sensor data, which may have distorted widely reported results.

Indoor Radon Levels In Dwellings of Kirklareli, Turkey

The indoor radon concentrations in Kirklareli, Turkey were measured in living rooms of 19 houses during winter in 2019 using Airthings 222 Corentium Home Radon Gas Detector. The short-term and long-term measurements were performed in 1 and 7 days for each house to investigate radioactive radon gas exposure in Kirklareli buildings. The indoor radon concentrations were varied from 23 to 156 Bq m-3 for 1 day period and were varied from 16 to 77 Bq m-3 for 7 days period. The average radon gas concentration was found as 43.5 Bq m-3 and this result is higher than the average of Turkey and the world average. The annual effective doses due to radon gas exposure were also estimated. The annual effective dose rate ranged from 0.61 to 2.94 mSv y-1 with a mean value of 1.09 mSv y-1.