Vehicle Emission Levels Research Articles

Evaluation of the accuracy of remote emission sensing measurements via real-world vehicle dynamic tests

To evaluate the measurement accuracy of horizontal and vertical remote emission sensing (RES) equipment, a real-world dynamic test was carried out in Chengdu by using electric vehicles equipped with various concentrations of standard gases. In addition, a new Image-based Spectral Processing Algorithm (ISPA) for vertical remote sensing spectral data was developed to improve the measurement capability. The results showed that the ISPA provided a greater percentage of valid data and lower relative errors; thus, our new algorithm could more effectively analyze the spectral data to measure vehicle emission levels. The percentages of valid horizontal and vertical RES data were 71% and 84%, respectively. The mean relative errors of CO2, CO, HC and NO measured by the vertical RES were about 5%, 20%, 20% and 40%, respectively, and those of CO2, CO and NO measured by the horizontal RES were 3%, 13% and 15%, respectively. For the common vehicle emission concentration, the percentage of valid data for the two RES types increased with increasing gas concentration. As the vehicle speed increased, the relative errors of the horizontal RES equipment showed an increasing trend for the same concentration of gas. Furthermore, for the same speed segment, the relative errors of the horizontal RES equipment increased as the simulated emission concentration decreased. The vertical RES equipment did not exhibit a consistent trend in terms of changes. This study provides a data quality reference for further RES applications.

Study on the development status and emission levels of methanol vehicles

Based on the research on the development status of methanol vehicles and formaldehyde testing technology at home and abroad, a comparison test was conducted between National V gasoline vehicles and methanol vehicles, and it was found that CO and THC emissions of methanol vehicles are lower than those of gasoline vehicles, NOx emissions are roughly the same as those of gasoline vehicles, and PM emissions are significantly lower; formaldehyde emissions are higher than those of gasoline vehicles. However, the existing testing methods cannot achieve direct and continuous testing of formaldehyde, and there is an urgent need to develop a direct measurement method for formaldehyde and corresponding testing equipment for in-use methanol-fuelled vehicles.

Experimental Investigation of Exhaust Gas Emission Status in Tanzania: A Case Study of National Institute of Transport Vehicle Inspection Center – Dar es Salaam

Exhaust gas emission is a by-product of air and fuel combustion in vehicle engines. It is a crucial contributing factor to air and environmental pollution that authorities emphasize controlling to mitigate the health and environmental hazards to communities. This was an experimental investigation to ascertain the emission status of used vehicles used for transport in Tanzania, some on the verge of surpassing their allowable emission levels. An experimental research design was opted for in this study and data were collected experimentally and through observations. Gas analyzers and emission detectors were used to obtain emission data for the study, where cluster sampling was preferred and 403 gasoline and diesel-powered vehicles were investigated for general inspection. The study found that engine size, year of manufacture, and kilometers of travel affected vehicle emission levels. The results were analyzed and compared with the allowable emission values in the Tanzanian standards.

Research on Analysis Method of Remote Sensing Results of NO Emission from Diesel Vehicles

Remote sensing technology has been used for gasoline vehicle gaseous emissions monitoring for nearly 30 years. However, the application effect of the remote sensing detection of diesel vehicle tailpipe emission concentrations is unsatisfactory. Therefore, several approaches were proposed to analyze the remote sensing results for gaseous exhaust emissions from diesel vehicles, including the concentration ratios of gaseous emission components to carbon dioxide (CO2) and fuel-based emission factors. Based on our experimental results, these two metrics have some high values in low-speed or low-load conditions of vehicles, which introduces uncertainty when evaluating vehicle emission levels. Therefore, an inversion calculation method originally developed for remote sensing light duty diesel vehicle gaseous emissions was used for the remote sensing of nitrogen monoxide (NO) tailpipe concentrations in heavy duty diesel vehicles, and validated by PEMS tested emission results. For the first time, the above three options for evaluating the NOx emission level of diesel vehicles, including the concentration ratio of NO to CO2, the fuel-based NO emission factor and the estimated tailpipe NO emission concentration were investigated, and some influencing factors were also discussed. The remote sensing tailpipe NO emission concentration can be directly used to evaluate diesel vehicle NO emission levels compared with the two other metrics.

Driving Cycles for Estimating Vehicle Emission Levels and Energy Consumption

Standard driving cycles (DCs) and real driving emissions (RDE) legislation developed by the European Commission contains significant gaps with regard to quantifying local area vehicle emission levels and fuel consumption (FC). The aim of this paper was to review local DCs for estimating emission levels and FC under laboratory and real-world conditions. This review article has three sections. First, the detailed steps and methodologies applied during the development of these DCs are examined to highlight weaknesses. Next, a comparison is presented of various recent local DCs using the Worldwide Harmonized Light-Duty Test Cycle (WLTC) and FTP75 (Federal Test Procedure) in terms of the main characteristic parameters. Finally, the gap between RDE with laboratory-based and real-world emissions is discussed. The use of a large sample of real data to develop a typical DC for the local area could better reflect vehicle driving patterns on actual roads and offer a better estimation of emissions and consumed energy. The main issue found with most of the local DCs reviewed was a small data sample collected from a small number of vehicles during a short period of time, the lack of separate phases for driving conditions, and the shifting strategy adopted with the chassis dynamometer. On-road emissions measured by the portable emissions measurement system (PEMS) were higher than the laboratory-based measurements. Driving situation outside the boundary conditions of RDE shows higher emissions due to cold temperatures, road grade, similar shares of route, drivers’ dynamic driving conditions, and uncertainty within the PEMS and RDE analysis tools.

COVID-19 pandemic impacts on traffic system delay, fuel consumption and emissions

A dramatic reduction in traffic demand has been observed during the COVID-19 pandemic, producing noticeable declines in traffic delays, energy consumption, and emissions. This unprecedented event provides us with the chance to investigate how limiting the number of vehicles on the transportation network can contribute to a better environment. This paper quantifies the effects of reduced traffic demand on vehicle delays, fuel consumption, and emission levels. Microscopic simulation was used to model traffic for seven different networks. Our results show that decreased traffic demand contributes significantly to reducing delays and emissions, especially in congested urban areas. The results also show that another important contributing factor is the network configuration. Specifically, networks with lower connectivity and fewer routing alternatives or networks with lower roadway density are more sensitive to traffic demand drops in terms of reducing vehicle delays and emissions.

Disparate air quality impacts from roadway emissions on schools in Santa Clara County (CA)

Vehicle emissions are major sources of air pollution linked to negative health outcomes in children. Consequently, California State Bill 352 stipulates that new schools may not be sited within 500 ft of major roadways. However, the exposure of existing schools to roadway emissions and the uneven distribution of the burden of air pollution have not been systematically explored for most cities. IN response, the objectives of our study were twofold: We used spatial analysis and an evaluation of traffic count data to develop a proximity-based approach to assessing school exposure to roadway air pollution emissions. Second, we applied our method to ask whether the risk of exposure to high concentrations of roadway emissions is equally distributed for schools in Santa Clara County (SCC; USA), and which demographic or spatial patterns emerge. In the process, our proximity-based approach estimated total annual traffic counts throughout SCC, identified major roadways, and assessed cumulative emission burdens and socio-economic indicators for each school in the study area. Results were compared to output from a physically-based model and to county asthma data. Our results suggest that (i) 14% of schools in SCC are potentially exposed to high levels of air pollution from roadways, a rate that is higher than the national average, and (ii) students from economically disadvantaged backgrounds and receiving aid are more likely to be educated in schools with higher risk of exposure to elevated levels of roadway vehicle emissions. Asthma hospitalization rates are highest in socio-economically disadvantaged areas with a higher density of major roadways. Areas of higher vehicle emissions determined by the physically-based model are in general agreement with those of the distance-based approach. We propose a combination of short- and long-term mitigation strategies to reduce the risk of exposure to vehicle emissions for school children.

Tourist tax to promote rentals of low-emission vehicles

In the Canary Islands (Spain), the tourism boom has been paralleled by sharp growth in the car rental sector. However, this economic activity is associated with problems such as rising levels of vehicle emissions. In this article, we discuss, on the one hand, the introduction of a tax to internalise the costs of emissions from car rental fleets and, on the other, the measures to reward users who rent environmentally-friendly cars. For this purpose, we propose a model based on statistical decision theory, from which a Bayesian rule is derived. According to this model, the tax increases with the number of days the car is rented but decreases in line with the environmental efficiency of the vehicle. A data sample of visitors to the Canary Islands is used to compare the covariates involved in computing the number of car rental days and the corresponding tax payable.

Development and Testing of a Novel Game Theoretic De-Centralized Traffic Signal Controller

The paper presents a novel de-centralized traffic signal controller, achieved using a Nash bargaining game-theoretic framework, that operates a flexible phasing sequence to adapt to dynamic changes in traffic demand levels. The Nash bargaining algorithm is used to optimize the traffic signal timings at each signalized intersection by modeling each phase as a player in a game, where players cooperate to reach a mutually agreeable outcome. The algorithm was implemented in the INTEGRATION microscopic traffic assignment and simulation software and tested on two sample networks. The proposed control approach was compared to the operation of an optimum fixed-time coordinated plan, an actuated controller, a centralized adaptive phase split controller, a decentralized phase split and cycle length controller, and a fully coordinated adaptive phase split, cycle length, and offset optimization controller to evaluate its performance. Testing was initially conducted on an isolated intersection, showing a 77% reduction in queue length, a a 64% reduction in vehicle delay, and a 17% reduction in vehicle emission levels. In addition, the algorithm was tested on an arterial network producing statistically significant reductions in total delay ranging between 36% and 67% and vehicle emission reductions ranging between 6% and 13%.

Health effects of PM2.5 emissions from on-road vehicles during weekdays and weekends in Beijing, China

Mobile source emissions have significantly contributed to fine particulate matter (PM2.5) pollution in urban atmospheric environments. Few studies have explored on-road vehicular PM2.5 emissions and the health effects attributed to these emissions under different traffic conditions. Based on driving data obtained from 20000 taxi receipts, a motor vehicle emission simulator (MOVES) model was used to estimate the PM2.5 emission levels of motor vehicles in the urban area within the Sixth Ring Road of Beijing (SRRB) on weekdays and weekends, respectively. Two different PM2.5 exposure scenarios were further simulated using an atmospheric dispersion model. Subsequently, the health effects attributable to traffic-related PM2.5 exposure were quantified by using exposure-response function to calculate the population acute morbidity and premature mortality during different time periods. We found that PM2.5 emission levels of motor vehicles on normal weekdays were overall higher than those on weekends. The median vehicular PM2.5 dispersion concentration in the study area was 2.68 μg/m3 on weekdays and 1.82 μg/m3 on weekends. Annually, there were 4435 premature deaths attributed to vehicle emissions (95% confidence interval (CI): 3655, 4904) under weekday exposure conditions, and this number sharply decreased to 3462 (95% CI: 3052, 4011) on weekends. Considering the hourly measurements, road traffic emissions have the greatest impact on public health during morning rush hour (8:00 a.m.). Total PM2.5 emissions were closely associated with road traffic conditions and largely determined the magnitude of the health impacts caused by traffic-related PM2.5 exposure. These findings provide information to aid in formulating reasonable public health policies to address vehicular PM2.5 emission-induced health implications.

Effects of climatic changes and urban air pollution on the rising trends of respiratory allergy and asthma


 
 
 Over the past two decades there has been increasing interest in studies regarding effects on human health of climate changes and urban air pollution. Climate change induced by anthropogenic warming of the earth’s atmosphere is a daunt- ing problem and there are several observations about the role of urbanization, with its high levels of vehicle emissions and other pollutants, and westernized lifestyle with respect to the rising frequency of respiratory allergic diseases observed in most industrialized countries. There is also evidence that asthmatic subjects are at increased risk of developing exacerbations of bronchial obstruction with exposure to gaseous (ozone, nitrogen diox- ide, sulfur dioxide) and particulate inhalable components of air pollution.
 A change in the genetic predisposition is an unlikely cause of the increasing frequency in allergic diseases because genetic changes in a population require several generations. Consequently, environmental factors such as climate change and indoor and outdoor air pollution may contribute to explain the increasing frequency of respiratory allergy and asthma. Since concentrations of airborne allergens and air pollutants are frequently increased contemporaneously, an enhanced IgE-mediated response to aeroallergens and enhanced airway inflammation could account for the increas- ing frequency of allergic respiratory diseases and bronchial asthma. Scientific societies such as the European Academy of Allergy and Clinical Immunology, European Respiratory Society and the World Allergy Organization have set up committees and task forces to produce documents to focalize attention on this topic, calling for prevention measures.
 
 
 

Characterisation of diesel vehicle emissions and determination of remote sensing cutpoints for diesel high-emitters

Diesel vehicles are a major source of air pollutants in cities and have caused significant health risks to the public globally. This study used both on-road remote sensing and transient chassis dynamometer to characterise emissions of diesel light goods vehicles. A large sample size of 183 diesel vans were tested on a transient chassis dynamometer to evaluate the emission levels of in-service diesel vehicles and to determine a set of remote sensing cutpoints for diesel high-emitters. The results showed that 79% and 19% of the Euro 4 and Euro 5 diesel vehicles failed the transient cycle test, respectively. Most of the high-emitters failed the NO limits, while no vehicle failed the HC limits and only a few vehicles failed the CO limits. Vehicles that failed NO limits occurred in both old and new vehicles. NO/CO2 ratios of 57.30 and 22.85 ppm/% were chosen as the remote sensing cutpoints for Euro 4 and Euro 5 high-emitters, respectively. The cutpoints could capture a Euro 4 and Euro 5 high-emitter at a probability of 27% and 57% with one snapshot remote sensing measurement, while only producing 1% of false high-emitter detections. The probability of high-emitting events was generally evenly distributed over the test cycle, indicating that no particular driving condition produced a higher probability of high-emitting events. Analysis on the effect of cutpoints on real-driving diesel fleet was carried out using a three-year remote sensing program. Results showed that 36% of Euro 4 and 47% of Euro 5 remote sensing measurements would be detected as high-emitting using the proposed cutpoints.

An optimization model of signal timing plan and traffic emission at intersection based on Synchro

With the rapid development of urbanization in China, the pressure of urban traffic keeps increasing. The problem of traffic pollution is increasingly serious as the automobile exhaust has been one of the main sources of urban air pollution. The major causes of traffic emission are the traffic jam and delay in the urban road intersections. Many advanced traffic signal control methods have been widely applied in the traffic management to reduce traffic jam. This paper proposes an optimization model of signal timing plan that comprehensively considers operating efficiency and traffic emission, which is based on signal timing plan for building a model of network topology and simulation for optimizing the signal timing. Meanwhile, this plan is to improve the efficiency of intersections, reduce queuing time and harmful emission. Taking some intersections in Harbin as an example, the measured pollutant emissions data at the intersections before and after signal optimization were collected and compared, then the levels of vehicle exhaust pollution and emissions of various emissions under different control strategies were analyzed, thus the emissions under different traffic management and control were evaluated. All these data has a great importance both in theoretical and practical value.

News on Climate Change, Air Pollution, and Allergic Triggers of Asthma.

The rising frequency of obstructive respiratory diseases during recent years, in particular allergic asthma, can be partially explained by changes in the environment, with the increasing presence in the atmosphere of chemical triggers (particulate matter and gaseous components such as nitrogen dioxide and ozone) and biologic triggers (aeroallergens). In allergic individuals, aeroallergens stimulate airway sensitization and thus induce symptoms of bronchial asthma. Over the last 50 years, the earth's temperature has risen markedly, likely because of growing concentrations of anthropogenic greenhouse gas. Major atmospheric and climatic changes, including global warming induced by human activity, have a considerable impact on the biosphere and on the human environment. Urbanization and high levels of vehicle emissions induce symptoms of bronchial obstruction (in particular bronchial asthma), more so in people living in urban areas compared than in those who live in rural areas. Measures need to be taken to mitigate the future impact of climate change and global warming. However, while global emissions continue to rise, we must learn to adapt to climate variability.

CORRELATION ANALYSIS OF DRIVING CONDITIONS AND ON-ROAD EMISSIONS TRENDS FOR VEHICLES

This paper presents the impact of road grade, vehicle speed, number of vehicles and vehicle type on vehicle emissions. ANOVA analyses were conducted among different driving conditions and vehicle emissions to discover the significant effects of driving conditions on measured emission rates. This study is intended to improve the understanding of vehicle emission levels in Jordan. Gas emissions in real-world driving conditions were measured by a portable emissions measurement unit over six sections of an urban road. The road grade, speed, type and number of vehicles were found to have a significant influence on the rate of gas emissions. Road grade and diesel-fueled vehicles were positively correlated with average emission rates. The average emission rates were higher at speeds ranging between 60–69 km/hr than at three other speed ranges. The results of ANOVA showed a strong and consistent regression between rates of emissions measured and grade, speed and diesel vehicle parameters. The grade parameter contributed the most to the rate of emissions compared to other parameters. Gasoline vehicles contributed the least.

Urban road traffic scale analysis from the perspective of atmospheric environmental indicators in Tianjin, China

In order to investigate the largest motor vehicle ownership load within the scope of a city with atmospheric environmental indicators as constraint, this article estimates traffic atmospheric environmental capacity (TAEC) and carrying capacity (TAECC) in Tianjin using the A-value method recommended by the Chinese national standard. Our results indicate that NOX carrying capacity is a key restraining factor of TAEC. According to the current vehicle emission levels per year and air quality standard, Tianjin can accommodate 4.21 million vehicles. Classified by the vehicle type, heavy trucks and large-sized passenger cars are identified as the most important restrictive factors of TAECC. Then we analyze change of TAECC and TAECC’s service life under the circumstances of clean vehicle strategy and mobility management strategy. Clean vehicles strategy represented by the elimination of heavy-polluting vehicles can reduce emissions of vehicles so that it can rapidly enhance the TAECC in the short term. Mobility management strategy represented by the car purchase restriction, which reduces total motor vehicle travel, is indispensable for improvement of TAECC in the long term. On the whole, the clean vehicles strategy and mobility management strategy should be implemented gradually.

CORRELATION ANALYSIS OF DRIVING CONDITIONS AND ON-ROAD EMISSIONS TRENDS FOR VEHICLES

This paper presents the impact of road grade, vehicle speed, number of vehicles and vehicle type on vehicle emissions. ANOVA analyses were conducted among different driving conditions and vehicle emissions to discover the significant effects of driving conditions on measured emission rates. This study is intended to improve the understanding of vehicle emission levels in Jordan. Gas emissions in real-world driving conditions were measured by a portable emissions measurement unit over six sections of an urban road. The road grade, speed, type and number of vehicles were found to have a significant influence on the rate of gas emissions. Road grade and diesel-fueled vehicles were positively correlated with average emission rates. The average emission rates were higher at speeds ranging between 60–69 km/hr than at three other speed ranges. The results of ANOVA showed a strong and consistent regression between rates of emissions measured and grade, speed and diesel vehicle parameters. The grade parameter contributed the most to the rate of emissions compared to other parameters. Gasoline vehicles contributed the least.

ESTIMATIVA DA POLUIÇÃO VEICULAR E QUALIDADE DO AR NAS PRINCIPAIS VIAS DO SISTEMA VIÁRIO DA REGIÃO CENTRAL DA CIDADE DE JUIZ DE FORA – MG

O aumento da população urbana vêm requerendo um crescente processo de mobilidade, porém vem se privilegiando os automóveis, aumentando sobremaneira o número de carros nas ruas e a consequente poluição atmosférica. Tornando vital para o controle da poluição do ar e visando a melhoria da qualidade de vida urbana torna-se fundamental deter o controle, monitoramento e estabelecer medidas para que a poluição do ar não se agrave. Desta forma, o presente artigo aplica para as principais vias do sistema viário da área central da cidade de Juiz de Fora, uma metodologia proposta por Taco (2006) e Filizola (2005) de estimativa da poluição veicular, permitindo conhecer a quantidade de CO e NOx /g/km/h. Os valores estimados permitiram criar cenários dos níveis de emissão veicular na área de estudo. Além disso, foi estabelecido uma série de mapeamentos temáticos da área de estudo afim de avaliar a contribuição do espaço urbano nos processos de dispersão/concentração da poluição nos diferentes pontos de contagem veicular. Por fim foi verificada a relação entre os valores estimados e o Índice de qualidade do ar (CETESB, 2013), no qual detecta-se que as piores condições de poluição atmosférica estão presentes nas vias mais estreitas e com acentuado fluxo de veículos.

Climate change, air pollution, and allergic respiratory diseases: an update.

The rising trend in prevalence of allergic respiratory disease and bronchial asthma, observed over the last decades, can be explained by changes occurring in the environment, with increasing presence of biologic, such as allergens, and chemical atmospheric trigger factors able to stimulate the sensitization and symptoms of these diseases. Many studies have shown changes in production, dispersion, and allergen content of pollen and spores because of climate change with an increasing effect of aeroallergens on allergic patients. Over the last 50 years, global earth's temperature has markedly risen likely because of growing emission of anthropogenic greenhouse gas concentrations. Major changes involving the atmosphere and the climate, including global warming induced by human activity, have a major impact on the biosphere and human environment.Urbanization and high levels of vehicle emissions are correlated to an increase in the frequency of pollen-induced respiratory allergy prevalent in people who live in urban areas compared with those who live in rural areas. Measures of mitigation need to be applied for reducing future impacts of climate change on our planet, but until global emissions continue to rise, adaptation to the impacts of future climate variability will also be required.

Climate Change and Air Pollution: Effects on Respiratory Allergy.

A body of evidence suggests that major changes involving the atmosphere and the climate, including global warming induced by anthropogenic factors, have impact on the biosphere and human environment. Studies on the effects of climate change on respiratory allergy are still lacking and current knowledge is provided by epidemiological and experimental studies on the relationship between allergic respiratory diseases, asthma and environmental factors, such as meteorological variables, airborne allergens, and air pollution. Urbanization with its high levels of vehicle emissions, and a westernized lifestyle are linked to the rising frequency of respiratory allergic diseases and bronchial asthma observed over recent decades in most industrialized countries. However, it is not easy to evaluate the impact of climate changes and air pollution on the prevalence of asthma in the general population and on the timing of asthma exacerbations, although the global rise in asthma prevalence and severity could also be an effect of air pollution and climate change. Since airborne allergens and air pollutants are frequently increased contemporaneously in the atmosphere, an enhanced IgE-mediated response to aeroallergens and enhanced airway inflammation could account for the increasing frequency of respiratory allergy and asthma in atopic subjects in the last 5 decades. Pollen allergy is frequently used to study the relationship between air pollution and respiratory allergic diseases, such as rhinitis and bronchial asthma. Epidemiologic studies have demonstrated that urbanization, high levels of vehicle emissions, and westernized lifestyle are correlated with an increased frequency of respiratory allergy prevalently in people who live in urban areas in comparison with people living in rural areas. Climatic factors (temperature, wind speed, humidity, thunderstorms, etc.) can affect both components (biological and chemical) of this interaction.