Search

Adverse health effects have been linked with exposure to livestock farms, likely due to airborne microbial agents. Accurate exposure assessment is crucial in epidemiological studies, however limited studies have modelled bioaerosols. This study used measured concentrations in air of livestock commensals (Escherichia coli (E. coli) and Staphylococcus species (spp.)), and antimicrobial resistance genes (tetW and mecA) at 61 residential sites in a livestock-dense region in the Netherlands. For each microbial agent, land use regression (LUR) and random forest (RF) models were developed using Geographic Information System (GIS)-derived livestock-related characteristics as predictors. The mean and standard deviation of annual average concentrations (gene copies/m3) of E. coli , Staphylococcus spp., tetW and mecA were as follows: 38.9 (±1.98), 2574 (±3.29), 20991 (±2.11), and 15.9 (±2.58). Validated through 10-fold cross-validation (CV), the models moderately explained spatial variation of all microbial agents. The best performing model per agent explained respectively 38.4%, 20.9%, 33.3% and 27.4% of the spatial variation of E. coli , Staphylococcus spp., tetW and mecA. RF models had somewhat better performance than LUR models. Livestock predictors related to poultry and pig farms dominated all models. To conclude, the models developed enable enhanced estimates of airborne livestock-related microbial exposure in future epidemiological studies. Consequently, this will provide valuable insights into the public health implications of exposure to specific microbial agents. [Display omitted] • Improving livestock exposure assessment is crucial for accurately assessing health risks. • Empirical spatial models effectively predict airborne microbial concentrations. • Random Forest models slightly outperform Land Use Regression models. • Variables related to poultry and pig farms are large contributors to the models. • Modelling residential exposure will benefit future epidemiological studies. [ABSTRACT FROM AUTHOR]

Household air pollution continues to be a global public health burden as 2.8 billion people still rely on open fires or inefficient cookstoves. The majority of morbidity and mortality are related to inhalation of fine particulate matter (PM), and many initiatives have focused on reducing PM emission and resulting exposure. For this reason, targets for emission rates to meet air quality guidelines have been set by the World Health Organization and International Organization for Standardization. These targets are based on a single-zone box model that assumes released particles are distributed uniformly throughout the kitchen. However, particulate matter is known to stratify vertically and therefore personal exposure to the cook and others in the kitchen may not be predicted accurately by a single-zone model. Therefore, this study compares empirical measurements of PM stratification to box model predictions to determine if the single-zone model is appropriate for predicting PM exposure at the expected breathing zone of the inhabitants. A test kitchen with a fixed ventilation rate and dimensions common to kitchens in rural areas was built and fitted with thirty HAPEx PM Sensors were evenly distributed at 4 different heights within the kitchen. Seventy modified water boiling tests were performed with a common rocket stove operating at known firepower and emissions rates in two testing phases at 10, 15 and 20 air exchanges per hour. Results showed stratification was less pronounced with increasing ventilation and with decreasing firepower. Measured concentrations at 15 ACH were compared to the predicted value from the single-zone model, showing equilibrium at a height of approximately 1.6 m. The box model over predicted concentration at heights lower than this, including a 23–63% excess at the 1.3 m high breathing zone of a typical standing cook. This implies that the current emission rate targets may be overly conservative under these conditions, precluding use of some types of biomass cookstoves that may actually be able to meet air quality guidelines. Future modeling and empirical studies should be conducted to understand under what conditions the use of the box model is appropriate, and when it should be modified for more accurate incorporation of the effects of stratification. • A test kitchen with standardized dimensions and adjustable ventilation was built. • PM concentration was monitored throughout the room in 70 tests at 3 air exchange rates. • Stratification was significant with decreasing ventilation. • The single-zone box model over-predicted concentration in the breathing zone. • Future research may be needed to improve the WHO emission rates targets. [ABSTRACT FROM AUTHOR]

With the extensive application of graphene oxide (GO), its leakage and release into wastewater treatment plants become inevitable. However, the toxicity of graphene oxide (GO) on nitrification process and the underlying mechanisms still remain unclear. In this study, the toxic effects of GO at concentration of 10 and 100 mg/L in 4 h and 10 days were evaluated with sealed reactors operated in sequencing batch mode. In the initial 4 h, both GO concentrations showed no negative effect on nitrogen conversion. However, the exposure to 100 mg/L GO significantly weakened the NH+ 4-N and NO- 2-N conversion capabilities and intensified the nitrous oxide (N 2 O) generation after 10 days. Extracellular polymeric substance (EPS) analysis suggested that 100 mg/L GO decreased the protein content of the nitrifying activated sludge. Moreover, reactive oxygen species (ROS) level was promoted by 100 mg/L GO owing to the impaired endogenous antioxidant enzymes including superoxide dismutase (SOD) and catalase (CAT), which caused oxidative stress to bacteria. Finally, quantitative PCR results confirmed that nitrite-oxidizing bacteria (NOB) and complete ammonia oxidizing bacteria (CAOB) were more sensitive to GO, which was the primary cause for the significant promotion of N 2 O generation in the high GO concentration. This study offered new insights in the toxicity of GO on nitrification and N 2 O generation in the terms of dose and exposure time. Image 1 • Short-term exposure of GO had no negative effect on nitrification and N 2 O emission. • Long-term exposure of GO weakened nitrifying capability and promoted N 2 O generation. • GO enhanced ROS generation and impaired the antioxidant enzymes SOD and CAT. • The inhibition of GO to NOB and CAOB led to higher production of NO- 2-N and N 2 O. Long-term exposure of GO significantly weakened the nitrifying capability and promoted N 2 O generation. [ABSTRACT FROM AUTHOR]

Temperature and area fluctuations in wetlands greatly influence its various physico-chemical characteristics, nutrients dynamic, rates of biomass generation and decomposition, floral and faunal composition which in turn influence methane (CH 4 ) emission rates. In view of this, the present study attempts to up-scale point CH 4 flux from the wetlands of Uttar Pradesh (UP) by modifying two-factor empirical process based CH 4 emission model for tropical wetlands by incorporating MODIS derived wetland components viz . wetland areal extent and corresponding temperature factors (F t ). This study further focuses on the utility of remotely sensed temperature response of CH 4 emission in terms of F t . F t is generated using MODIS land surface temperature products and provides an important semi-empirical input for up-scaling CH 4 emissions in wetlands. Results reveal that annual mean F t values for UP wetlands vary from 0.69 (2010–2011) to 0.71(2011–2012). The total estimated area-wise CH 4 emissions from the wetlands of UP varies from 66.47 Gg yr −1 with wetland areal extent and F t value of 2564.04 km 2 and 0.69 respectively in 2010–2011 to 88.39 Gg yr −1 with wetland areal extent and F t value of 2720.16 km 2 and 0.71 respectively in 2011–2012. Temporal analysis of estimated CH 4 emissions showed that in monsoon season estimated CH 4 emissions are more sensitive to wetland areal extent while in summer season sensitivity of estimated CH 4 emissions is chiefly controlled by augmented methanogenic activities at high wetland surface temperatures. [ABSTRACT FROM AUTHOR]

To investigate the pedestrian exposure to fine particulate on various typical urban roadways, mass concentration of PM10, PM2.5, PM1 and particle number concentrations in the given size distribution were obtained at four types of urban roads in Xi’an City: urban expressway, arterial road, collector road, and local road. The principal component analysis (PCA) was used. Measurement and analysis results showed that the mean particle number concentration for the size range of 0.25–32 μm on the urban expressway was 9%, 29% and 32% higher than those on the arterial road, the collector road and the local road, respectively. However, the mass concentration of particles, especially for PM2.5 and PM1, varied little. Traffic volumes on the urban expressway, the collector road and the local road all had important influences on PM particle-number concentration, but at different size ranges. Additionally, the results discussion indicated that PM10, PM2.5 and PM1 were generated from the same emission source(i.e. vehicles)on the urban expressway, yet on the other types of roads PM (especially PM10 and PM1) emissions were generated from different sources (i.e. vehicles, pedestrians, or road dust). [ABSTRACT FROM AUTHOR]

Traffic exhaust is a main source of fine particulate matter (PM 2.5) in cities. Heavy-duty diesel trucks (HDDTs), the primary mode of freight transport, contribute significantly to PM 2.5 , posing a great threat to public health. However, existing research based on dispersion models to simulate pollutant concentrations lacks high-spatiotemporal-resolution emission inventories of HDDTs as input data, and the public health effects of such emissions in different populations have not been thoroughly assessed. To fill this gap, we focused on Beijing as the research area and developed a high-resolution PM 2.5 emission inventory for HDDTs based on Global Navigation Satellite System-equipped vehicle trajectory data. We then simulated the fine-scale spatial distribution of diesel-related PM 2.5 and assessed the population exposure by integrating the dispersion model and population distributions. Further, we quantified the mortality attributable to noncommunicable diseases (NCDs) plus lower respiratory infections (LRIs) related to PM 2.5 emissions from HDDTs. Results showed that 3.3% of Beijing people lived in areas with high PM 2.5 HDDT emissions, which were near intercity highways. Furthermore, the estimated number of NCD + LRI annual premature deaths attributed to PM 2.5 HDDT emissions in Beijing was 339 (95% CI: 276–401). The NCD + LRI mortality increased with age, and deaths were more frequent in males than females. Our results aid the identification of HDDT PM 2.5 emission exposure hotspots for the formulation of effective mitigation measures and provide important insights into the adverse health impacts of HDDT emissions. [Display omitted] • High PM 2.5 exposure from heavy-duty diesel trucks affects 3.3% of Beijing residents. • Per-capita PM 2.5 exposure from heavy-duty diesel trucks is higher in 20–44 age group. • PM 2.5 from heavy-duty diesel trucks caused higher male mortality than female. [ABSTRACT FROM AUTHOR]

It is a win–win technology to inject CO 2 into the oil or gas reservoirs. Because it can reduce the greenhouse gas emission and enhance oil recovery. In some oil or gas reservoirs, the reservoir water and the strong heterogeneity make the CO 2 storage capacity difficult to be determined. In this research, the CO 2 storage evaluation method is introduced. This method considers the CO 2 displacement efficiency, the CO 2 sweep efficiency, the CO 2 dissolution in oil and gas and the CO 2 displacement mechanism. The key factors in this evaluation method are determined by the reservoir simulation method, the thermodynamic theories and the statistical analysis methods separately. At last, the CO 2 storage capacity evaluation system is built. This system can be used to evaluate the CO 2 storage capacity fast and reliably and it worth to be promoted in the area of CO 2 storage. [ABSTRACT FROM AUTHOR]

Abstract: A 3D numerical model was developed to investigate the effect of foil emissivity on the effective thermal resistance of an above-grade wall assembly with foil bonded to wood fibreboard in a furred assembly having airspace next to the foil. This model solved simultaneously the energy equation in the various material layers, the surface-to-surface radiation equation in the furred airspace assembly, Navier–Stokes equation for the airspace, and Darcy and the Brinkman equations for the porous material layers. In this work, the furring was installed horizontally. In the first phase, the present model was benchmarked against the experimental data generated by a commercial laboratory for an above-grade wall assembly. The wall consists of a conventional wood frame structure sheathed with fibreboard and covered on the interior side with a low emissivity material bonded to wood fibreboard that is adjacent to a furred airspace assembly. The results showed that the predicted R-value was in good agreement with the measured one. After gaining confidence in the present model, it was used to predict the effective thermal resistance of the same above-mentioned wall but having Oriented Strand Board (OSB) sheathing in lieu of wood fibreboard sheathing. In the second phase, the model was used to quantify the contribution on the wall R-value by having a low foil emissivity. The results showed that a low foil emissivity of 0.04 can increase the R-value of this wall to as much as ∼9%. This is on-going research. The present model is being used to investigate the transient thermal response of foundation wall systems with furring installed horizontally and vertically, and subjected to different Canadian climate conditions. [Copyright &y& Elsevier]

There is a great potential to reduce greenhouse gas (GHG) emissions related to livestock production. For achieving this potential will require new initiatives at national and international levels that include promoting research and development on new mitigation technologies; deploying, diffusing and transferring technologies to mitigate emissions; and enhancing capacities to monitor, report and verify emissions from livestock production. This study describes the sources of livestock-related GHG emissions and reviews available mitigation technologies and practices. We assess the main policy instruments available to curb emissions and promote carbon sinks, and discuss the relative merits of alternative approaches. We discuss recent experiences in countries that have enacted mitigation strategies for the livestock sector to illustrate some of the key issues and constraints in policy implementation. Finally, we explore the main issues and challenges surrounding international efforts to mitigate GHG emissions and discuss some possible ways to address these challenges in future climate agreements. [ABSTRACT FROM AUTHOR]

Genetic improvement of livestock is a particularly effective technology, producing permanent and cumulative changes in performance. This paper highlights some of the options for including mitigation in livestock breeding schemes, focusing on ruminant species, and details three routes through which genetic improvement can help to reduce emissions per kg product via: (i) improving productivity and efficiency, (ii) reducing wastage in the farming system and (iii) directly selecting on emissions, if or when these are measurable. Selecting on traits that improve the efficiency of the system (e.g. residual feed intake, longevity) will have a favourable effect on the overall emissions from the system. Specific examples of how genetic selection will have a favourable effect on emissions for UK dairy systems are described. The development of breeding schemes that incorporate environmental concerns is both desirable and possible. An example of how economic valuation of public good outcomes can be incorporated into UK dairy selection indices is given. This paper focuses on genetic selection tools using, on the whole, currently available traits and tools. However, new direct and indirect measurement techniques for emissions will improve the potential to reduce emissions by genetic selection. The complexities of global forces on defining selection objectives are also highlighted. [ABSTRACT FROM AUTHOR]

2-Ethyl-1-hexanol (2E1H) is sometimes detected in indoor air at relatively high concentrations. The emission mechanism for 2E1H is considered to be that moisture with a high pH in concrete slabs and self-leveling sub-flooring material reacts with di-2-ethylhexyl phthalate (DEHP) in the polyvinyl chloride (PVC) flooring and compounds containing the 2-ethyl-1-hexyl group in the adhesive. 2E1H is considered to be one of the causes of odor in indoor air and sick building syndrome, so it is important to clarify the 2E1H emission mechanism for IAQ. However, there are few reports on any experimentation into 2E1H emission by chemical reaction involving building materials. In this study, PVC floorings are attached using various adhesives to a self-leveling sub-flooring material that contains water, and their 2E1H emission rates are measured. Furthermore, the components of the adhesives are determined using chemical analysis. It is found that 2E1H emission rates from the floor are affected by the type of adhesive used. On the other hand, some components in the adhesives may suppress the hydrolysis of esters. The hydrolysis of polymers and residual monomers in the adhesive causes 2E1H emission from the adhesive. [Copyright &y& Elsevier]

Abstract: This paper presents an experimental modeling of contaminant dispersion in a mock-up isolation room with different negative pressure differentials and ventilation rates. A hypothetical contaminant (sulfur hexafluoride, SF6) is emitted from a patient lying on a bed in the mock-up isolation room. The impacts of ventilation rates 12 and 24h−1 and pressure differentials −2.5, −5.0, −8.0, and −15.0Pa on the ventilation effectiveness in the room are evaluated quantitatively. A local air quality index and an exposure index for healthcare workers are introduced in the research to evaluate the ventilation efficiency of the isolation room. Based on the results of our experiment, the ventilation efficiency of the isolation room ranks the highest at −15.0Pa/24h−1, followed, respectively, by −15.0Pa/12h−1, −8.0Pa/24h−1, −5.0Pa/24h−1, −2.5Pa/24h−1, −8.0Pa/12h−1, −5.0Pa/12h−1, and −2.5Pa/12h−1. [Copyright &y& Elsevier]

Abstract: In order to estimate the dynamic structure of the VLF ionospheric exit point, we conducted multipoint ground-based observation of the natural VLF emissions at three unmanned sites: West Ongul (69°01′ S, 39°30′ E), Skallen (69°40′ S, 39°24′ E), and H100 (69°18′ S, 41°19′ E) around Japanese Syowa station, Antarctica, during a whole year of 2006. In this observation, we developed three sets of unmanned autonomous observation systems for natural VLF emissions. Each observation system consists of two crossed vertical loop antennas to pick-up North–South (NS) and East–West (EW) magnetic components, a multi-channel analyzer, and a data logger. The intensity and polarization of NS and EW magnetic components are obtained in 4 spaced frequency (0.5, 1.0, 2.0, and 6.0kHz) channels by the multi-channel analyzer. The VLF emissions observed at the three sites exhibit an interesting difference in the wave intensity as well as the polarization that allows important information about the locations of their ionospheric exit point to be determined. Firstly, to find the distinct exit point, we have theoretically calculated the spatial distributions of the wave intensity and the polarization on the Earth for VLF whistler mode waves coming down from the magnetized ionosphere, by using the full-wave analysis. Then, we have compared the calculated results with the observed data, to evaluate the possible locations of the ionospheric exit point for the auroral hiss events. As an example, the direction of the estimated ionospheric exit point for the auroral hiss event at 31 March 2006 was found to be consistent with a bright aurora region. However, in this case, the estimated ionospheric exit point was located a few hundred kilometers equatorward of the associated aurora. This would suggest that the ray paths for the auroral hiss could be different from the directions of the geomagnetic field lines for auroral precipitation. [Copyright &y& Elsevier]

• Gaseous and particulate pollutants measured at four distinct urban hotspots in Tehran, Iran. • The major source of gaseous and particulate pollutants was traffic emissions. • Particulate concentrations were higher in winter, especially the first three days of the work week. • HQ for both PM 2.5 and PM 10 in different age groups exceeded the acceptable limit. • HQ for PM 2.5 and PM 10 in both seasons for 4 bus terminals exceeded the acceptable limit. This study reports a characterization of outdoor gaseous and particulate pollutants and their associated health effects in four different urban hotspots in Tehran, Iran during winter and summer. Buses, taxis, and cars are prominent sources of toxic pollutants in Tehran. There is a significant level of exposure to emissions from diesel buses in bus terminals, especially with boarding, disembarking, and waiting. Mean concentrations (μg/m3) in summer and winter, respectively, ranged from 10 to 20.67 and 17–21 for PM 1 , 52.50–79.19 and 58.33–85.33 for PM 2.5 , 64.50–102 and 78.83–125.83 for PM 7 , 130.17–204.67 and 157–231.67 for PM 10 , 261–409.50 and 305.83–458.83 for TSP, and 372.50–418.33 vs. 351.27–373.47 for CO 2 (ppm). Particulate concentrations were higher in winter, especially the first three days of the week, assisted in part by the shallower mixing layer height as compared to summer. Mean hazard quotient (HQ) values for both PM 2.5 and PM 10 in both seasons for bus terminals in three scenarios ranged between 0.81 and 4.96, which exceeded reference levels (1 < HQ). The results of this study have implications for public health, especially in dense traffic areas. [ABSTRACT FROM AUTHOR]

Firing ranges critically depend on ventilation systems to minimize the exposure of personnel to ammunition refuse. A numerical analysis utilizing a computational fluid dynamics (CFD) method was used to simulate the ventilation system and predict airflow patterns within a 122-foot long, military firing range housing 21 firing stalls. The intent for this model was to identify back circulation causing firing emissions to entrain in occupied areas. Measured values at several locations within the facility were used for either input values in the model or for validation of the model solution. The analysis evaluated massless particles released at three heights to correspond with standing, kneeling, and prone firing positions. Additional predictions were completed using the recommended technical guidance for ventilation of small arms firing ranges to compare against flow dynamics of the current system. The results revealed particles circulating back behind the shooter and into the personnel occupied area. Lower supply air velocities correspond to more uniform flow and successful movement of particles downrange in the small arms firing range under investigation. The ventilation air velocity at the firing line recommended by the design guide was not achieved consistently despite the supply air velocity being set to design guide values. Overall, the results demonstrated that CFD models are useful aides for optimizing supply air velocities in current firing range facilities and for evaluating and developing design standards that provide the proper ventilation required for the health and safety of building occupants. • Developed computational model simulating firing emissions exposure due to ventilation air flow in a small arms, military, firing range and verified predictions with measured data. • Developed additional models using US Air Force design guidelines to showing ammunition particulates were not removed when standards were met. • Air flow velocities at the firing line per design guide were not achieved even when the recommended supply air flow was specified. • Firing emissions simulated particulate circulated into occupied area at actual supply air velocities and when velocities were set within the higher design standard velocity range. • Simulation predictions indicate occupants may be exposed to firing emissions from lead-free frangible ammunition which could be the cause of reported health effects by personnel. [ABSTRACT FROM AUTHOR]

Brakes, tyres and road deposits have become important contributors to the overall particle emissions of vehicles globally, with constituents in these wear particles considered to be harmful to human health (PM 10 and PM 2.5). Previous research has documented mass/size distributions, physical and chemical characteristics, emission factors and long-term implications and environmental occurrences. The complex path these pollutants take from their origins to the environment, however, is not fully understood. This is partly owing to the breadth of spatio-temporal scales involved in the advection-diffusion processes (nanometers to meters, microseconds to minutes). These short timescale particle transport mechanisms impact human exposure, such as pedestrians and cyclists, and initiate the long-term interaction of these pollutants with other environmental compartments. Here, we present an analysis for urban driving conditions to highlight the opportunities to reveal these complex pathways and formulate opinions that aim to stimulate future enquiry. We describe important vehicular areas and exposure scenarios where efforts should focus. Future interdisciplinary research into these particle transport mechanisms must be prioritised as it can provide the foundation for developing urgently needed pollution control strategies, transport infrastructure layouts and transport policies that mitigate, or possibly eliminate pollution exposure risks. [ABSTRACT FROM AUTHOR]

Food carts are common along streets in cities throughout the world. In North America, food cart vendors generally use propane, charcoal, or both propane and charcoal (P and C) for food preparation. Although cooking emissions are known to be a major source of indoor air pollution, there is limited knowledge on outdoor cooking's impact on the ambient environment and, in particular, the relative contribution of the different cooking fuels. This field study investigated the air pollution the public is exposed to in the micro-environment around 19 food carts classified into 3 groups: propane, charcoal, and P and C carts. Concentrations near the food carts were measured using both real-time and filter-based methods. Mean real-time concentrations of PM 2.5 , BC 2.5 , and particle counts were highest near the charcoal food carts: 196 μg/m3, 5.49 μg/m3, and 69,000 particles/cm3, respectively, with peak exposures of 1520 μg/m3, 67.9 μg/m3, and 235,000 particles/cm3, respectively. In order of pollution emission impacts: charcoal > P and C > propane carts. Thus, significant differences in air pollution emissions occurred in the vicinity of mobile food carts, depending on the fuel used in food preparation. Local air pollution polices should consider these emission factors in regulating food cart vendor operations. Image 1 • Mobile food carts produce significant air pollution compared with the control sites. • Near charcoal carts, PM 2.5 concentrations were 12 fold higher than background sites. • Peak levels of PM 2.5 near charcoal carts were as high as 1500 μg/m3. • The charcoal PM 2.5 emissions were ∼6 times higher compared to propane food carts. • Air pollution impacts order: charcoal > propane and charcoal > propane food carts. [ABSTRACT FROM AUTHOR]

Polybrominated diphenyl ethers (PBDEs) serve as flame retardants in many household materials such as electrical and electronic devices, furniture, textiles, plastics, and baby products. Though the use of PBDEs like penta-, octa- and deca-BDE greatly reduces the fire damage, indoor pollution by these toxic emissions is ever-growing. In fact, a boom in the global market projections of PBDEs threatens human health security. Therefore, efforts are made to minimize PBDEs pollution in USA and Europe by encouraging voluntary phasing out of the production or imposing compelled regulations through Stockholm Convention, but >500 kilotons of PBDEs still exist globally. Both 'environmental persistence' and 'bioaccumulation tendencies' are the hallmarks of PBDE toxicities; however, both these issues concerning household emissions of PBDEs have been least addressed theoretically or practically. Critical physiological functions, lipophilicity and toxicity, trophic transfer and tissue specificities are of utmost importance in the benefit/risk assessments of PBDEs. Since indoor debromination of deca-BDE often yields many products, a better understanding on their sorption propensity, environmental fate and human toxicities is critical in taking rigorous measures on the ever-growing global deca-BDE market. The data available in the literature on human toxicities of PBDEs have been validated following meta-analysis. In this direction, the intent of the present review was to provide a critical evaluation of the key aspects like compositional patterns/isomer ratios of PBDEs implicated in bioaccumulation, indoor PBDE emissions versus human exposure, secured technologies to deal with the toxic emissions, and human toxicity of PBDEs in relation to the number of bromine atoms. Finally, an emphasis has been made on the knowledge gaps and future research directions related to endurable flame retardants which could fit well into the benefit/risk strategy. Image 1 • Household toxic emissions and exposure of humans to PBDEs are quite alarming. • In-use PBDE products are the major sources of indoor emissions and their pollution. • Health risks and high body burden of PBDEs are serious in children of urban areas. • BDE-209, a congener of deca-BDE debromination, greatly affects human health. • Site-specific model indoor studies for all 209 congeners are needed for their HRAs. [ABSTRACT FROM AUTHOR]

Kitchen emissions are mixed indoor air pollutants with adverse health effects, but the large-scale assessment is limited by costly equipment and survey methods. This study aimed to discuss the application of backpropagation (BP) neural network models in the assessment of kitchen emissions based on the exposure marker. A total of 3686 participants were recruited for the kitchen survey, and their sleep quality was measured by the Pittsburgh sleep quality index (PSQI). After excluding the confounders, 365 participants were selected to assess their urinary hydroxy polycyclic aromatic hydrocarbons (OH-PAHs) concentrations by ultra-high-performance liquid chromatography/tandem mass spectrometry. Two BP neural network models were then set up using the survey and detection data from the 365 participants and used to predict the total urinary OH-PAHs concentrations of all participants. The total urinary OH-PAHs and 1-hydroxy-naphthalene (1-OHNap) concentrations were significantly higher among the 365 participants with poor sleep quality (global PSQI score > 5; P < 0.05). Results from internal and external validation showed that our model has high credibility (model 2). Further, the participants with higher predicted total urinary OH-PAHs concentrations were associated with the global PSQI score of >5 (odds ratio (OR) = 1.284, 95% confidence interval (CI) = 1.082–1.525 for participants with predicted total urinary OH-PAHs concentrations of over 1.897 μg/mmol creatinine in model 1, and OR = 1.467, 95% CI = 1.240–1.735 for participants with predicted total urinary OH-PAHs concentrations of over 2.253 μg/mmol creatinine in model 2) after adjusting for the confounders. Findings suggest that the BP neural network model is suitable for assessing kitchen emissions, and the urinary OH-PAHs concentrations can be taken as the model outlay. Image 1 • BP neural network model can be taken as an assessment method for kitchen emissions. • Exposure markers like total urinary OH-PAHs can be taken as the model outlay. • People with higher predicted total urinary OH-PAHs levels had poorer sleep quality. • BP neural network model can be applied to environmental health research. The BP neural network model can be applied in assessing kitchen emissions, and the urinary OH-PAHs concentrations can be taken as the model outlay. [ABSTRACT FROM AUTHOR]

Associations between human exposures to vehicular emissions (VE) and cardiopulmonary diseases have been found, with a dearth of information on particle cytotoxicity. This study exposes human lung alveolar epithelial (A549) cells to PM 2.5 (particulate matter with aerodynamic diameter <2.5 μm) samples collected in a tunnel and investigates the oxidative and inflammatory responses. The cytotoxicity factor (CF) is used to normalize the VE cytotoxicity. The emission factors (EFs) were 27.2 ± 12.0 mg vehicle−1 km−1 for PM 2.5 and 4.93 ± 1.67 μg vehicle−1 km−1 for measured polycyclic aromatic hydrocarbons (PAHs). Higher EFs were found for high (4–6 rings) than low (2–3 rings) molecular-weight particulate PAHs. PM 2.5 VE caused oxidative stress and inflammation of human lung cells. Organic carbon (OC), element carbon (EC), and several PAHs were significantly (p < 0.05) correlated with bioreactivity. Higher CFs were found when diesel vehicle counts were highest during the morning rush hour, implying that diesel-fueled VE were major contributors to cytotoxic effects. This study provides a broader understanding of the toxicity in an engine-exhaust dominated environment. • Vehicle emissions cause oxidative and inflammatory responses in human lung cells. • Increased cytokines are related to vehicle-emitted polycyclic aromatic hydrocarbons. • A vehicle cytotoxicity emission factor is derived. • Diesel-fueled vehicles are the major contributors to the cytotoxic effects. This study evaluates the oxidative and inflammatory responses from PM 2.5 samples collected in a traffic dominated Hong Kong tunnel. [ABSTRACT FROM AUTHOR]

Macro-models provide a fast simulation tool for exposure assessments and design of control interventions, yet there are concerns about their accuracies. Single-zone based models are known to be inadequate for predicting exposure to near-source emissions, while the complexity of sequential box models (SBM) limits their application to steady-state conditions. However, treating unsteady conditions as steady underestimates peak inhalation exposure potentials, especially near the source. This study employs a sub-configuration validation approach to validate the unsteady SBM, using an R open-source-based numerical solver, for estimating indoor pollutant concentration, exposure and/or infection risks. The validated model is used to assess the performance of ASHRAE S170-2017 baseline specifications for inhalation exposure control in a multi-bed patient ward with air recirculation. In the baseline studies, quanta infective concentration and reference concentration were respectively used as source strength and threshold values for influenza pathogen. Robust design methodology was employed in the experimental design and analysis of the control and noise factors. Results indicate a close relationship between SBM and the sub-configuration validation datasets. Findings also show that concentration gradients exist in SBM with the highest values in the near-field zones. Thus, with SBM, the well-mixed assumption does not necessarily imply equal exposure potentials. Robustness analysis shows that stratum ventilation is three-fold insensitive to the variability in exposure than mixing ventilation. Finally, the results of the case studies revealed that the average inhalation exposure exceeds the influenza reference concentration, thereby suggesting an insufficiency of the baseline conditions to offer protection against inhalation exposure to influenza contagion. • We studied sub-configuration validation of sequential box model (SBM). • We validate deSolve open source R-package for SBM applications. • SBM adequately capture concentration gradients in exposure assessment. • Stratum ventilation is three-fold robust for exposure control than mixing ventilation. • ASHRAE S170 baseline appears insufficient to control exposure with air recirculation. [ABSTRACT FROM AUTHOR]