High Emission Levels Research Articles

Co-combustion of methane hydrate granules and liquid biofuel

The use of fossil hydrocarbons is accompanied by such problems as the depletion of energy resources and high levels of anthropogenic emissions. One of the options for solving these problems can be the involvement in the fuel sector of composite mixed fuels using gas hydrates and vegetable liquid bio-fuels. In this research we test a hypothesis that gas hydrate with added rapeseed oil will make an energy-efficient and environmentally friendly composite fuel. According to the experimental findings, the co-combustion of gas hydrates and liquid biofuels shows high potential. It shortens the ignition delay by 1.5 times at 700 °C in the combustion chamber and by half at 800 °C compared with the combustion of methane hydrate alone. It also produces 18–32% less carbon monoxide, 12–22% less nitrogen oxides, and 14–33% less sulfur oxides than the direct combustion of rapeseed oil. On the basis of the results obtained, we have developed a predictive mathematical model simulating the heat transfer in a layer of composite fuel. A methane hydrate and rapeseed oil mixing scheme is proposed for combustion chambers. We also provide recommendations on how to use the research findings in a number of energy-related applications.

A study on the impacts of antibiotic pollution and its remediation

AbstractAntibiotics' ability to treat bacterial infections has long been seen as a pillar of modern medicine. Antibiotic abuse and widespread overuse, however, have resulted in unexpected consequences that call for significant adjustments in policy to be mitigated. High levels of antibiotic emissions from manufacturing facilities may help to develop new types of resistant bacteria. Such pollution is acknowledged by many scientists, business leaders, decision‐makers, and other interested parties as an unneeded and intolerable risk to public health worldwide. Antibiotics are frequently produced by soil microorganisms. The bacteria and fungi are microorganisms that produce antibiotics that are helpful in preventing or treating disease. With the invention of Penicillin, antibiotics gained widespread recognition. Since then, they have fundamentally changed how bacterial infections in animals and humans are treated. Since a significant portion of antibiotics are released from human and animal bodies without being degraded, this means that various environmental components, including soils and river water, are contaminated with antibiotics. In this case, it is anticipated that the structure and productivity of the microbiota inhabiting such environments may be impacted by the varied concentration of this type of microbial inhibitor present in different ecosystems. This effect can take place at various levels, including modifications to the population's overall structure, the selection of resistant species, or changes to bacterial physiology.

Unregulated economic activities and the environment: The role of fiscal policies

African countries are characterized by high unofficial activities, coupled with a fiscal structure that could either undermine or promote these activities to affect the environment. This study examines the direct and indirect environmental impacts of the unregulated economy and the fiscal instruments of government expenditure and tax using the panel quantiles regression technique. Driven by data availability, our analysis covers 46 countries when the fiscal variables are not considered, while 41 and 38 countries are respectively included in the models involving government expenditure and tax revenue from 2000 to 2016. We discover that the direct impact of unofficial economic activities is unfavourable on the environment, as it increases carbon emissions. The direct impacts of the fiscal policies are heterogeneous. The environmental effect of government expenditure changes from favourable to unfavourable as the countries move from low to high emissions levels. On the other hand, tax is only environmentally friendly in countries with moderate levels of emissions. The interactive effect of an unregulated economy and government expenditure worsens and improves the environment at low and high emissions levels, respectively. The results are heterogeneous for the interactive effect of unregulated economy and tax, although they are more biased toward a satisfactory impact on the environment at the extreme quantiles. Appropriate regulation of informal activities and the design of effective fiscal policy frameworks for environmental sustainability are policy derivatives of these findings.

The uphill struggles of carsharing in the Netherlands.

The current mobility system relies heavily on privately owned cars, which results in high levels of emissions, material use, and use of scarce public space. Carsharing is a mobility innovation offering consumers on-demand, short-term access to cars. By changing consumption patterns and reducing car ownership, carsharing has great potential to contribute to a sustainability transition of the mobility system. Even so, carsharing only satisfies a small portion of today's mobility needs and has difficulties becoming mainstream. This study investigates the upscaling trajectory of carsharing in the Netherlands. We structure the analysis along the lines of the multilevel perspective and include economic, technological, sociocultural, and policy factors that shape carsharing growth. The results demonstrate how car ownership is entrenched in the social and economic fabric, and the specific barriers this poses to carsharing. Moreover, we find some forms of carsharing risk extending private car ownership rather than challenging it. The environmental outcomes of carsharing are not predetermined but depend on the trajectories key actors take during upscaling. Our analysis highlights the importance of studying innovations in the context of the consumption-production systems in which they emerge.

Soft computing techniques to predict the compressive strength of groundnut shell ash-blended concrete

Using groundnut shell ash (GSA) as a component in concrete mixtures is a viable approach to achieving sustainability in building practices. This particular kind of concrete has the potential to effectively mitigate the issues associated with high levels of CO2 emissions and embodied energy, which are primarily attributed to the excessive utilization of cement in conventional construction materials. When GSA is utilized as a partial replacement for cement, the strength characteristics of concrete are influenced not only by the quantity of GSA replacement but also by several other factors, including cement content, water-to-cement ratio, coarse aggregate content, fine aggregate content, and curing length. This work demonstrates a predictive model for the compressive strength (CS) of GSA mixed concrete using ML methods. The models were constructed with 297 datasets obtained from published literature. These datasets included various input variables such as cement content, GSA content, fine aggregate content, coarse aggregate content, water need, and curing duration. The output variable included in the models was the CS of concrete. In this study, a set of seven machine learning algorithms was utilized as statistical assessment tools to identify the most precise and reliable model for predicting the CS of GSA mixed concrete. These techniques included linear regression, full quadratic model, artificial neural network, boosted decision tree regression, random forest regression, K nearest neighbors, and support vector regression. The present study evaluated several machine learning models, and it was shown that the random forest regression model had superior performance in forecasting the CS of GSA mixed concrete. The train data’s R2 is 0.91, with RMSE of 2.48 MPa. Similarly, for the test data, the R2 value is 0.89, with an RMSE of 2.42 MPa. The sensitivity analysis results of the random forest regression model indicate that the cement content primarily drives the material’s CS. Subsequently, the curing period and GSA content significantly impact the CS. This work systematically evaluates the CS of GSA mixed concrete, contributing to the existing body of knowledge and practical implementation in this domain.

Air Quality Analysis of Indoor Working Environments from Different Industries and Regions of Punjab

Background: Air pollution is a major health hazard and one of most crucial environmental aspects which cause mass mortality of population. Workers in different factories often directly exposed to particulate matter which can initiate respiratory related problems which may steer to incidence of cancer. Materials and Methods: Various particulate matter (PM) fractions and gaseous emissions were monitored in indoor environments of different industries using DRX Aerosol Monitor. Parallel monitoring of PM2.5 was performed in outdoor air by using TSI DUSTTRAK. Besides, analyses of indoor environment of different industrial units for volatile organic carbon (VOC’s), temperature, relative humidity, gaseous emissions (CO, CH4, O3, and NO2) was done by using Aeroqual. Results: The levels of particulate matter (PM) of all fractions and other criteria pollutant gases were significantly higher in all manufacturing units compared with recommended permissible WHO limits. Furthermore, PM2.5 levels were significantly higher in outdoor environment as compared to indoor workplaces at all monitored sites. Conclusion: There is a dire need to consider these high levels of PM and other gaseous emissions and take some serious steps to control this ever-increasing problem.

Spatial and socioeconomic characteristics of CO2 emissions and sequestration in Indonesian cities

In dealing with the impacts of climate change, mitigation efforts play a crucial role. As one of the G20 countries on the list of the top 5 biggest contributors to emissions, Indonesia must play an active role. With all their characteristics and as one of the most significant contributors to global emissions, cities are fully responsible as a core area for climate mitigation. By analyzing the spatial and socioeconomic characteristics within the city scope, this study examines 32 representative cities and municipalities in Indonesia to understand the condition of carbon emissions and sequestration. Emissions and sequestration in selected cities in Indonesia show varying statuses; most cities have higher emission levels than sequestration, but some cities do the opposite. In addition, emissions and sequestration are also influenced by many complex and interrelated factors, including spatial (distribution, intensity, LULC, geographical conditions, total area), social (total population, urbanization rate, employment rate), economic (GDP/GRDP), and technological (industry structure and energy sector). As an archipelagic country, the uniqueness of cities in Indonesia, primarily located in coastal and waterfront areas, also influences the emission intensity, which tends to be lower in these areas on a micro basis. Cities classified as economically developed contribute more emissions at the national level. Therefore, a characteristic-based classification of the selected cities can encourage policy implications according to the characteristics of each city. These cities can learn from each other, especially from cities with high sequestration rates, to develop in a sustainable way while supporting national mitigation targets.

CO2 emissions from service sectors in Ecuador: an analysis using input–output subsystems

AbstractEcuador is one of the most megadiverse countries in the world and a pioneer in establishing some regulations to take care of its environment. Despite this, its levels of pollution and environmental deterioration are higher than those of neighboring countries. A better understanding of the pollution channels of a subsystem such as services, which increasingly occupies a more relevant place in the economy and many of its activities tend to go unnoticed as a source of pollution, allows the development of mitigation strategies that could be analyzed and adopted for similar contexts. We estimated direct and indirect emissions for the 71 economic activities of Ecuador and applied an input–output subsystem analysis, breaking down the generation of total CO2 emissions (direct and indirect) of the 18 activities that make up the services subsystem into 6 sources. Total emissions of the services subsystem were a third of the emissions for the year 2018. Although it is known that transport is a well-known relevant actor in overall CO2 emissions, our decomposition provides a clearer view of the direct and indirect pollution channels of other relevant service sectors. We detect several service sectors with an insignificant level of direct CO2 emissions and a high level of total emissions. This is the case of trade services, real estate services, services provided by professionals, telecommunications or the government public administration. These sectors induce the generation of emissions from other sectors inside and outside the services subsystem. The results inform the design of policies to mitigate CO2 emissions in Ecuador.

The Effects of Cracking Ratio on Ammonia/Air Non-Premixed Flames under High-Pressure Conditions Using Large Eddy Simulations

Ammonia is a promising carbon-free fuel. However, one of the main challenges for ammonia combustion is the high level of NO emissions. In this study, simulations were conducted for ammonia/air laminar counterflow flames and turbulent non-premixed jet flames in the KAUST high-pressure combustion duct (HPCD) at a pressure of 5 bar, with two ammonia cracking ratios of 14% and 28%. The influence of ammonia cracking ratio on the flame structure and NO formation mechanism were examined. The laminar counterflow flame results showed that HNO is one of the most critical species related to NO formation and NO is mainly generated through the path of NH2→NH→HNO→NO. For the turbulent flames, the flamelet/progress variable (FPV) approach was employed in the context of large eddy simulations (LES) for high-fidelity simulations. The simulation results were compared with the measured data with promising agreements, which proves the accuracy of the FPV method for the present flames. It was shown that with increasing cracking ratio, not only the flame reactivity is enhanced, but also the generation of NO is increased. The correlation between NO and HNO is weaker when compared to that between NO and radicals such as O, H and OH in the entire flame. Through the distribution of NO source terms, it was found that the NO source term has a higher absolute value in the upstream region and the absolute value rapidly decreases with increasing streamwise distance. The total NO source term is positive in the fuel-lean zone and shows negative values in the fuel-rich zone.

Exergy and energy analysis of Organic Rankine Cycle integration in the carbon black industry using pinch technology

Industrial Carbon black production is a petrochemical process that has high level of waste heat and emissions. Main points of CB process include furnace and stack lines. Also, the use of different feedstocks can be effective in level of waste heat and amount of emission pollutants. So the main objective of this research use from the pinch technology in CB process in order to minimize the level of waste heat by utilization of waste heat recovery (WHR) applications for power generation. By numerical investigation and modelling of WHR in furnace and stack points, can be defined best location for power generation in CB process. Moreover, through the analysis of Organic Rankine Cycle (ORC) systems integrated with WHR from both energy and exergy perspectives, second target to enhance their thermal efficiency. The results indicate that the presence of blowers on stacks leads to an increase in RoHR and RoHC. In order to determine the optimal location for power generation cycle installation, an ORC energy and exergy analysis was conducted. The results showed that the energy and exergy values at the SLC stack were higher than those at the HLC point. Also, numerical results showed the points that have suitable thermal efficiency and rate of exergy of WHR where have higher temperature gradient than other points. So SLC (ĖxWHR=166.7kW) and HLC (ĖxWHR=136.1kW) stacks integrated with blower are the optimal location for WHR utilization in the CB production process.

Tracer-Gas-Integrated Measurements of Brake-Wear Particulate Matter Emissions from Heavy-Duty Vehicles.

Automotive brake-wear emissions are increasingly important in on-road particulate matter (PM) emission inventory. Previous studies reported a high level of PM emissions from the friction materials of light/medium-duty vehicles, but there are few data available from heavy-duty (HD) vehicles equipped with drum brakes despite their popularity (∼85% in HD vehicle fleet). This study developed a novel tracer-gas-integrated method for brake-wear PM emission measurements and evaluated four HD vehicles on a chassis dynamometer that complied with regulatory exhaust emission testing requirements. Three class-6 vehicles with a similar test weight demonstrated repeatability, with the coefficient of variation in the range of 9-36%. Braking events increased PM concentrations by 3 orders of magnitude above the background level. Resuspension of brake-wear PM also occurred during acceleration and contributed to 8-31% of the total PM2.5 mass. The class-6 vehicles had PM2.5 emissions from a single brake (0.7-1.5 mg/km/brake), generally similar to the level of tail-pipe exhaust PM emissions (0.7-1.5 mg/km/vehicle) of each vehicle. A class-8 vehicle exhibited brake-wear PM2.5 emissions (2.4-3.4 mg/km/brake) significantly higher than the tail-pipe exhaust PM emissions (∼1.3 mg/km/vehicle). This article reports an exceptionally high level of brake-wear PM emissions measured directly from the drum brakes of HD vehicles.

Short-term exposure to sulfur dioxide and daily mortality in Brazil: A nationwide time-series study between 2003–2017

Sulfur dioxide (SO2), despite its ubiquitousness, there is relatively less epidemiological evidence regarding the health risks associated with SO2 compared to other pollutants, especially in low-income countries where there are high levels of SO2 emissions. In this study, we estimated the association between ambient SO2 exposure and daily mortality in Brazil over a period of 15 years (2003–2017). We used an extension of the two-stage time-series design in a time-series analytic approach with a distributed lag model. The study population consisted of 2,872,084 death records, with a higher proportion of male deaths observed across all-cause mortality (58%). The majority of the individuals were aged above 65 years. The mean SO2 concentration across the study period was 1.5 μg/m³ (range: 0.0 to 71.0). The national meta-analysis for the whole dataset (without stratification by sex and age) showed an uncertain association, in which a 10 μg/m3 increase in daily SO2 was associated with an RR of mortality of 1.015 (95%CI: 0.992; 1.037). Robust associations were observed only for the subgroup analysis of people 46–65 years old [RR = 1.050 (95%CI: 1.004; 1.096)] and men 46–65 years old [RR = 1.064 (95%CI: 1.005; 1.122)]. We found moderate heterogeneity in the national analysis, with an I2 of 21% for the subgroup of people 46–65 years old. Excess mortality fraction for people between 46 and 65 years old attributable to per 10 μg/m3 increase in SO2 was 2.93% (95% eCI: 0.29%–6.78%). These results highlight the need for targeted air pollution control policies to reduce the health burden of SO2 exposure in Brazil. Further research is needed to fully understand the mechanisms behind the age-specific and regional effects of SO2 on mortality.

Features of Stimulating the Issue of Green Bonds in the Modern Economy

There are large number of companies that form investment portfolios of modern investors have a high level of CO2 emissions. In particular, such sectors of the economy include the oil and gas sector, metallurgy, electricity. For the transition of these sectors of the economy to a car-bon-neutral status, it is necessary to attract significant funding. One of the main instruments of such financing is green bonds. The purpose of the study is to develop a mechanism to encourage companies to implement green projects by issuing green bonds with coupon payments, which will be partially compensated. In the course of studying the problem posed, possible options for linking the Carbon Border Adjustment Mechanism (CBAM) and green bonds were also considered. The study was conducted on the basis of methods of comparison, modeling, analysis and deduction. The result of the work is the developed mechanism of tax incentives for the issuance of green bonds by companies, which can be applied in any country. The study was conducted taking into account the introduction of additional reducing coefficients to the mineral ex-traction tax, property tax and income tax. The study showed that in the case of partial compensation of coupon payments on bonds, the state does not need to introduce lowering coefficients to the tax rate, it is enough to use a tax deduction from income tax in the amount of the planned compensation of coupon payments.

The effect of geopolitical risk on carbon emissions: influence mechanisms and heterogeneity analyzed using evidence from China.

To meet the goals of reducing adverse effects, continuing economic transformation, and achieving sustainable development, it is necessary to understand the impact mechanism and heterogeneous effects of geopolitical risk on carbon emissions. Using panel data from 30 provinces in China gathered between 2003 and 2019, we show that (1) geopolitical risk significantly contributes to the growth of carbon emissions, as does non-renewable energy consumption, trade, and economic growth, but that technological progress, industrial structure upgrading, and marketization inhibit the growth of carbon emissions; (2) geopolitical risk inhibits carbon emissions by suppressing non-renewable energy consumption and trade, and promoting technological progress; and (3) geopolitical risk has heterogeneous effects on carbon emissions in different quartiles. In the lower quartiles (i.e., groups with lower emission levels), geopolitical risk suppresses carbon emissions, while in higher quartiles (i.e., groups with higher emission levels), geopolitical risk promotes carbon emissions. As growing geopolitical risk and carbon emissions are now common problems for all countries, this study serves as a valuable reference not only for China, but for every member of the global community seeking to mitigate geopolitical risk shocks and achieve carbon emission reduction targets.

Reconfiguration of last-mile supply chain for parcel delivery using machine learning and routing optimization

Last-mile delivery has several negative environmental impacts in urban areas because of its high levels of greenhouse gas emissions and air pollution, as well as traffic congestion. These issues motivate decision-makers to redesign the delivery networks and make them more sustainable and efficient. A well-planned territory design can reduce total travel times and distances in urban distribution systems, in addition to balancing the workload between drivers. In this study, a two-echelon parcel distribution network modeled as the two-echelon vehicle routing problem with territory design and satellite location decisions is considered. A three-stage decomposition algorithm is proposed to solve this problem. In the first stage, a non-supervised machine learning clustering method is applied, followed by an algorithm based on the nearest-neighbor routing procedure, to find a set of routes for the second and first echelons. An improvement heuristic was also applied to improve the results in terms of the second echelon routing, considering the computational complexity of a large-scale instance. A case study based on real data from a delivery company in the city of Paris, France is adopted to perform the experiments. The outcomes of this paper show an improvement of 22.6% in travel time and distance. This reduction is also assessed with performance indicators like land use, fixed costs, energy consumption, carbon dioxide equivalent, and fine particles emissions.

Research on the Factors Influencing CO2 Emission Reduction in High-Energy-Consumption Industries under Carbon Peak

In the context of reaching peak carbon emissions, it is crucial to develop carbon reduction strategies for high-energy-consuming industries as part of a broader societal transition from dependence on high-pollution energy sources to low-pollution alternatives. This study focuses on carbon emission reduction in the non-ferrous metal industry, which is known for its significant energy consumption. It employs the Logarithmic Mean Divisia Index (LMDI) model to conduct empirical analyses from three perspectives: carbon emission decomposition, regionalization analysis, and carbon emission prediction. The objective is to explore the carbon emission characteristics of high-energy-consuming industries in China and provide theoretical support for future policies aimed at reducing carbon emissions in these industries. The findings reveal that the economic scale of the non-ferrous metal industry has a positive correlation with carbon emissions, while carbon emission coefficients exhibit a negative correlation. Moreover, in the prediction scenarios considered, the increase in carbon emissions resulting from the economic-scale factor accounted for 75.28%, 87.46%, and 65.21% respectively, indicating that it has the most significant influence among all factors analyzed. The study further demonstrates that under stable and active emission reduction scenarios, the future potential for carbon dioxide emission reduction in the non-ferrous metal industry is estimated to reach 858.47 million tons and 1384.65 million tons, respectively. These figures represent twice and three times the emissions recorded in 2021. By analyzing the factors influencing emission reduction, targeted regulations can be implemented to develop practical and effective strategies for reducing carbon emissions in the industry. From the analysis conducted, it can be deduced that high-energy-consuming industries, particularly the non-ferrous metal industry, exhibit relatively high levels of carbon emissions. Consequently, it is imperative to implement proactive measures to reduce these emissions. Additionally, the industry’s carbon emissions are heavily influenced by changes in economic scale due to its high dependence on it. This highlights the importance of considering economic factors when devising strategies to mitigate carbon emissions. Furthermore, the potential for improvement in the non-ferrous metal industry’s energy structure and carbon emission coefficients is limited. Simply relying on technological innovation alone may not suffice to achieve significant emission reduction goals. Therefore, it becomes crucial for the government to develop tailored emission reduction targets and policies based on the industry’s specific circumstances to attain optimal results.

Study on spatiotemporal distribution characteristics and driving factors of carbon emission in Anhui Province

Carbon emission is related to global ecological security, and economic development inevitably leads to an increase in carbon emission. In recent years, as a rapidly developing province in China's economy, Anhui Province has experienced significant differences in the spatiotemporal distribution of carbon emission in different regions due to differences in development foundation, urbanization level, population size, industrial structure, etc., providing representative empirical cases for research. Based on the carbon emission data of Anhui Province before the COVID-19, this study used exploratory spatial data analysis method and Geodetector to analyze the spatial and temporal distribution characteristics and drivers of carbon emission in Anhui Province. The study found that (1) the spatial differentiation and spatial correlation of carbon emission in Anhui Province are significant, At the beginning, it shows the characteristics of "high north and low south" and "high west and low east", and then the "core–edge" structure of carbon emission becomes obvious. Carbon emission hotspot areas increase and then decrease, mainly in Hefei, Fuyang and Chuzhou City, etc. The coldspot areas are mainly located in the southern and western mountainous areas, and the degree of aggregation is decreasing year by year. (3) The level of urbanization, economic development and population size are the main driving factors of the spatial variation of carbon emissions, while the industrial structure has the least influence. And most factors produce nonlinear enhancement when spatially superimposed with other factors. (4) The high value areas of economic development, population density, secondary industry structure, and energy intensity are all at high levels of carbon emission, and a combination of factors leads to the creation of high risk areas for carbon emission. The study provides a basis for reducing carbon emission in the next stage of Anhui Province, focusing on key carbon emission areas, and sustainable development.

Dual issue of resources and emissions: Resources richness and Carbon Emissions with Oil rents, trade, and mineral rents exploration

Climate change is a global issue of paramount importance, posing significant challenges to the sustainability of our planet. The issue of climate change and its associated challenges have garnered considerable attention from researchers worldwide. The BRICS nations hold a significant position in contributing to global CO2 emissions. These countries have experienced rapid economic growth and industrialization, which have led to an upsurge in energy consumption and subsequent CO2 emissions. Natural resources play a crucial role in the economic development of nations, including the BRICS countries. However, the extraction and utilization of these resources can have significant environmental consequences, including CO2 emissions. Hence, understanding the impact of natural resource rents on carbon emissions becomes particularly relevant. This study aims to analyse the relationship between natural resource rents (forest rents, mineral rents, and oil rents) and carbon emissions in the BRICS countries over the period of 1989–2021. Using advanced analytical approaches, we find that resource rents, along with imports, and GDP are positively related with carbon emissions. The finding implies that the economic benefits derived from forest resources, such as timber production and ecosystem services, may contribute to increased carbon emissions through activities like deforestation and land-use changes. Moreover, we find that exports reduce CO2 while higher levels of imports are associated with higher levels of emissions in BRICS nations.

Thermal performance enhancement of a red-hot air furnace for a micro-scale externally fired gas turbine system

Externally-fired gas turbine (EFGT) has been considered an option in variable combined heat and power energy systems. The key elements in such systems are the high-temperature heat exchangers (HTHE), in which the working fluid (typically air) is heated by flue gas. Since both flows are separated, the solution is considered advantageous for utilization of biomass featuring high levels of particulate matter emissions. An increased interest in these devices has therefore been observed along with the development of small-scale CHP units utilizing locally available biomass. The effectiveness of HTHE, along with the inlet turbine temperature, appears to be one of the main factors influencing the efficiency of EFGT-based systems. Numerous studies on the HTHE designs have been carried out, basically focusing on the use of high-temperature resistant materials to provide safe conditions for long-term operation under elevated temperatures. There is a lack of research considering other methods to improve the effectiveness of the HTHE. The paper presents the analysis of thermal performance of the laboratory-scale 20 kW red-hot air furnace to demonstrate the HTHE effectiveness enhancement by adding water to airflow. The experimental results showed a significant increase (by almost 45%) in the heat exchanger effectiveness for the case of ∼10%wt. water addition. This is due to the enhanced heat capacity of a cooling medium and its absorption properties that results from the steam content. The proposed method for effectiveness increment appears to be beneficial to compensate for the low effectiveness of air-to-fumes tube HTHE.

Urinary Amino-PAHs in relation to diesel engine emissions and urinary mutagenicity

Diesel exhaust has long been of health concern due to established toxicity including carcinogenicity in humans. However, the precise components of diesel engine emissions that drive carcinogenesis are still unclear. Limited work has suggested that nitrated polycyclic aromatic hydrocarbons (NPAHs) such as 1-nitropyrene and 2-nitrofluorene may be more abundant in diesel exhaust. The present study aimed to examine whether urinary amino metabolites of these NPAHs were associated with high levels of diesel engine emissions and urinary mutagenicity in a group of highly exposed workers including both smokers and nonsmokers. Spot urine samples were collected immediately following a standard work shift from each of the 54 diesel engine testers and 55 non-tester controls for the analysis of five amino metabolites of NPAHs, and cotinine (a biomarker of tobacco smoke exposure) using liquid chromatography–mass spectrometry. An overnight urine sample was collected in a subgroup of non-smoking participants for mutagenicity analysis using strain YG1041 in the Salmonella (Ames) mutagenicity assay. Personal exposure to fine particles (PM2.5) and more-diesel-specific constituents (elemental carbon and soot) was assessed for the engine testers by measuring breathing-zone concentrations repeatedly over several full work shifts. Results showed that it was 12.8 times more likely to detect 1-aminopyrene and 2.9 times more likely to detect 2-aminofluorene in the engine testers than in unexposed controls. Urinary concentrations of 1-aminopyrene were significantly higher in engine testers (p < 0.001), and strongly correlated with soot and elemental carbon exposure as well as mutagenicity tested in strain YG1041 with metabolic activation (p < 0.001). Smoking did not affect 1-aminopyrene concentrations and 1-aminopyrene relationships with diesel exposure. In contrast, both engine emissions and smoking affected 2-aminofluorene concentrations. The results confirm that urinary 1-aminopyrene may serve as an exposure biomarker for diesel engine emissions and associated mutagenicity.