Potential impacts of electric vehicles on air quality in Taiwan

Updating vehicle VOCs emissions characteristics under clean air actions in a tropical city of China

In the context of clean air actions in China, vehicle emission limits have been continuously tightened, which has facilitated the reduction of volatile organic compounds (VOCs) emissions. However, the characteristics of VOC emissions from vehicles with strict emission limits are poorly understood. This study investigated the VOC emission characteristics from vehicles under the latest standards based on tunnel measurements, and identified future control strategies for vehicle emissions. The results showed that the highest percentage of VOCs from vehicle consisted of alkanes (80.9 %), followed by aromatics (15.8 %) and alkenes (3.1 %). Alkanes had the most significant ozone formation potential due to their high concentrations, in contrast to the aromatics that have been dominant in previous studies. The measured fleet-average VOC emission factor was 71.3 mg·km-1, including tailpipe emissions of 39.6 mg·km-1 and evaporative emissions of 31.7 mg·km-1. The VOC emission factors of the subgroups were obtained. The emission of evaporated VOCs accounted for 44.5 % of the total vehicle VOC emissions, which have increased substantially from previous studies. In addition, the emission characteristics of vehicles that are under the latest emission threshold values have changed significantly, and the mixing ratio of toluene/benzene (T/B) has been updated to 3:1. This study updates the VOCs emission factors of vehicles under clean air actions and highlights the future mitigation policies should focus on reducing evaporative VOC emissions.

Large Decreases in Tailpipe Criteria Pollutant Emissions from the U.S. Light-Duty Vehicle Fleet Expected in 2020-2040

The U.S. EPA MOVES3 model was used to assess the impact of the large-scale introduction of electric vehicles on emissions of criteria pollutants (CO, hydrocarbons [HC], NOx, and particulate matter [PM]) and CO2 from the U.S. light-duty vehicle fleet. Large reductions in emissions of these criteria pollutants occurred in 2000-2020. These trends are expected to continue through 2040 driven by turnover of the conventional fleet with old vehicles being replaced by battery electric vehicles (BEVs) and by new internal combustion engine vehicles (ICEVs) with modern emission control systems. Without the introduction of BEVs, the absolute emissions of CO, NOx, HC, and PM2.5 from the U.S. light-duty vehicle fleet are expected to decrease by approximately 61, 88, 55, and 20% from 2020 to 2040. Introduction of BEVs with market share increasing linearly to 100% in 2040 provides additional benefits, which, combined with ICEV fleet turnover, would lead to decreases of absolute emissions of CO, NOx, HC, and PM2.5 of approximately 77, 94, 71, and 37% from 2020 to 2040. Reductions in CO2 emissions follow a similar pattern. Large decreases in criteria pollutant and CO2 emissions from light duty vehicles lie ahead.

How electric vehicles benefit urban air quality improvement: A study in Wuhan

Urban air quality is a global concern, and while numerous studies have examined the impact of geography, climate, and urban development on air quality, few have considered the role of electric vehicles (EVs) in predictive models. Furthermore, little attention has been paid to the spatial heterogeneity of EVs. Given the rapid growth of the EV industry, it is crucial to understand the increasing significance of EVs and electric vehicle charging stations (EVCS) on air quality. This study focuses on Wuhan, a representative polycentric city, to investigate the combined effects of EVs and EVCS on air quality, alongside other urban factors. The study employs Markov chains (MC) to process air quality data and utilizes Ordinary Least Squares (OLS) and Multiscale Geographically Weighted Regression (MGWR) for data modeling. The results highlight that incorporating EV and EVCS variables enhances the model's fit. Notably, EVCS demonstrates a pronounced influence on improving air quality in areas with high plot ratios and building densities along the north bank of the Yangtze River. The study identifies spatial variations in the geographic distribution of both EVs and EVCS, as well as the distribution of MGWR coefficients. Three distinct regional centers in Wuhan exhibit high concentrations of EVCS per unit area. Moreover, the projected outcomes suggest that these three regions can anticipate significant improvements in air quality, with probabilities ranging from 3.93 % to 10.06 %, 4.40 % to 11.43 %, and 2.55 % to 6.52 % in achieving an Excellent Status (S1) for future air quality, under the assumption of maintaining current EV policies. This study advances our understanding of the contribution of EVs and EVCS to air quality within polycentric cities. It introduces novel research perspectives and methodologies, enriching related fields of study. The findings can inform policymakers and urban planners in developing strategies for creating cleaner and more efficient cities.

Spatial and Cross-Sectoral Transfer of Air Pollutant Emissions from the Fleet Electrification in China by 2030

Fleet electrification shifts emission sources from the tailpipe to electricity generation and automotive supply chains subsequently, with emission transfer among regions. Such a spatial and cross-sectoral transfer of air pollutant emissions might embody uncertain environmental benefits spatially, which has not been comprehensively quantified, mainly due to the complexity of manufacturing processes of electric vehicle (EV) components (e.g., battery). We developed a hybrid life cycle assessment by combining inventory data of major processes and cross-sectoral input-output information and identified how China's EV deployment would influence the spatial redistribution of air pollutant emissions currently (2017) and in the future (2030). The results indicate that fleet electrification could readily reduce life cycle nitrogen oxides (NOx) and nonmethane volatile organic compound (NMVOC) emissions by 12-93%, and the reductions are estimated to be concentrated in major cities and urban agglomerations. However, increased demand for electricity and power battery production could increase PM2.5 and SO2 emissions in 17-55% of grids under all the scenarios, which emerge in coal-rich (e.g., Inner Mongolia, Shanxi) and industrial (e.g., Shandong, Henan, Jiangsu) provinces. By tracing the upstream, 31-55% of vehicle-cycle emissions are from deep supply chains but exhibit diverse sources. It suggests the necessity to relieve emissions leakage of fleet electrification by synchronizing effective environmental management across multiple sectors through EV supply chains.

California's zero-emission vehicle adoption brings air quality benefits yet equity gaps persist

Zero-emission vehicle (ZEV) adoption is a key climate mitigation tool, but its environmental justice implications remain unclear. Here, we quantify ZEV adoption at the census tract level in California from 2015 to 2020 and project it to 2035 when all new passenger vehicles sold are expected to be ZEVs. We then apply an integrated traffic model together with a dispersion model to simulate air quality changes near roads in the Greater Los Angeles. We found that per capita ZEV ownership in non-disadvantaged communities (non-DACs) as defined by the state of California is 3.8 times of that in DACs. Racial and ethnic minorities owned fewer ZEVs regardless of DAC designation. While DAC residents receive 40% more pollutant reduction than non-DACs due to intercommunity ZEV trips in 2020, they remain disproportionately exposed to higher levels of traffic-related air pollution. With more ZEVs in 2035, the exposure disparity narrows. However, to further reduce disparities, the focus must include trucks, emphasizing the need for targeted ZEV policies that address persistent pollution burdens among DAC and racial and ethnic minority residents.

Potential Impacts of Energy and Vehicle Transformation Through 2050 on Oxidative Stress-Inducing PM2.5 Metals Concentration in Japan

The impacts of renewable energy shifting, passenger car electrification, and lightweighting through 2050 on the atmospheric concentrations of PM2.5 total mass and oxidative stress-inducing metals (PM2.5-Fe, Cu, and Zn) in Japan were evaluated using a regional meteorology-chemistry model. The surface concentrations of PM2.5 total mass, Fe, Cu, and Zn in the urban area decreased by 8%, 13%, 18%, and 5%, respectively. Battery electric vehicles (BEVs) have been considered to have no advantage in terms of non-exhaust PM emissions by previous studies. This is because the disadvantages (heavier weight increases tire wear, road wear, and resuspention) offset the advantages (regenerative braking system (RBS) reduces brake wear). However, the future lightweighting of drive battery and body frame were estimated to reduce all non-exhaust PM. Passenger car electrification only reduced PM2.5 concentration by 2%. However, Fe and Cu concentrations were more reduced (-8% and -13%, respectively) because they have high brake wear-derived and significantly reflects the benefits of BEV's RBS. The water-soluble fraction concentration of metals (induces oxidative stress in the body) was estimated based on aerosol acidity. The reduction of SOx, NOx, and NH3 emissions from on-road and thermal power plants slightly changed the aerosol acidity (pH ± 0.2). However, it had a negligible effect on water-soluble metal concentrations (maximum +2% for Fe and +0.5% for Cu and Zn). Therefore, the metal emissions reduction was more important than gaseous pollutants in decreasing the water-soluble metals that induces respiratory oxidative stress and passenger car electrification and lightweighting were effective means of achieving this.

Source-apportionment and spatial distribution analysis of VOCs and their role in ozone formation using machine learning in central-west Taiwan

This study assessed the machine learning based sensitivity analysis coupled with source-apportionment of volatile organic carbons (VOCs) to look into new insights of O₃ pollution in Yunlin County located in central-west region of Taiwan. One-year (Jan 1 to Dec 31, 2021) hourly mass concentrations data of 54 VOCs, NO_X, and O₃ from 10 photochemical assessment monitoring stations (PAMs) in and around the Yunlin County were analyzed. The novelty of the study lies in the utilization of artificial neural network (ANN) to evaluate the contribution of VOCs sources in O₃ pollution in the region. Firstly, the station specific source-apportionment of VOCs were carried out using positive matrix factorization (PMF)-resolving six sources viz. AAM: aged air mass, CM: chemical manufacturing, IC: Industrial combustion, PP: petrochemical plants, SU: solvent use and VE: vehicular emissions. AAM, SU, and VE constituted cumulatively more than 65% of the total emission of VOCs across all 10 PAMs. Diurnal and spatial variability of source-segregated VOCs showed large variations across 10 PAMs, suggesting for distinctly different impact of contributing sources, photo-chemical reactivity, and/or dispersion due to land-sea breezes at the monitoring stations. Secondly, to understand the contribution of controllable factors governing the O₃ pollution, the output of VOCs source-contributions from PMF model along with mass concentrations of NO_X were standardized and first time used as input variables to ANN, a supervised machine learning algorithm. ANN analysis revealed following order of sensitivity in factors governing the O₃ pollution: VOCs from IC > AAM > VE ≈ CM ≈ SU > PP ≈ NO_X. The results indicated that VOCs associated with IC (VOCs-IC) being the most sensitive factor which need to be regulated more efficiently to quickly mitigate the O₃ pollution across the Yunlin County.

California's early transition to electric vehicles: Observed health and air quality co-benefits

The transition to electric vehicles is projected to have considerable public health co-benefits, but most evidence regarding air quality and health impacts comes from projections rather than real-world data. We evaluated whether population-level respiratory health and air quality co-benefits were already detectable at the relatively low levels of zero-emissions vehicles (ZEVs: battery electric, plug-in hybrid, hydrogen fuel cell vehicle) adoption in California, and evaluated the ZEV adoption gap in underserved communities. We conducted a zip code-level ecologic study relating changes in annual number of ZEVs (nZEV) per 1000 population from 2013 to 2019 to: (i) annual average monitored nitrogen dioxide (NO2) concentrations and (ii) annual age-adjusted asthma-related emergency department (ED) visit rates, while considering educational attainment. The average nZEV increased from 1.4 per 1000 population in 2013 (standard deviation [SD]: 2.1) to 14.7 per 1000 in 2019 (SD: 14.7). ZEV adoption was considerably slower in zip codes with lower educational attainment (p < 0.0001). A within-zip code increase of 20 ZEVs per 1000 was associated with a - 0.41 ppb change in annual average NO2 (95 % confidence interval [CI]:-1.12, 0.29) in an adjusted model. A within-zip code increase of 20 ZEVs per 1000 population was associated with a 3.2 % decrease in annual age-adjusted rate of asthma-related ED visits (95 % CI:-5.4, -0.9). Findings were supported by a variety of sensitivity analyses. Observational data on the early phase ZEV transition in California provided a natural experiment, enabling us to document the first real-world associations between increasing nZEV and changes in air quality and health. Results suggest co-benefits of the early-phase transition to ZEVs but with an adoption gap among populations with lower socioeconomic status which threatens the equitable distribution of possible co-benefits.

Air quality improvement through vehicle electrification in Hainan province, China

To improve the ecological environment, provinces in China have set ambitious goals for the electrification of fossil-fuel-powered vehicles (FVs) and the promotion of electric vehicles (EVs). Hainan is the first province to propose a clean energy target that schedules the banning of new FVs sales from 2030. Therefore, Hainan is a good case study to illustrate how this policy might improve regional air quality over the coming years. This study first developed an anthropogenic emission inventory of seven major air pollutants in 2017 in Hainan. The total emissions of CO, NOx, NH3, volatile organic compounds (VOCs), PM10 and PM2.5 and SO2 in 2017 were estimated as 247.56, 69.61, 61.87, 41.38, 37.02, 19.82, and 8.55 kt, respectively. Using the developed emission inventory, multiple scenarios of economic development were considered to assess the benefits to air quality from Hainan's goal of electrification. In comparison with 2017, the reductions in emissions of SO2, NOx, CO, PM10, PM2.5, VOCs, and NH3 by 2045 were projected to be 5.45 (11.11%), 275.07 (57.32%), 675.51 (34.07%), 8.39 (5.73%), 7.73 (8.24%), 81.15 (9.76%), and 4.89 (0.91%) kt, respectively, under the all-electric vehicle scenarios. These results indicate that this policy will not only reduce the emission of air pollutants but also avoid complex O3 pollution in the future. The findings of this work elucidate the effects of vehicle electrification policies on regional air quality and provide scientific support for policymakers in developing pollution control strategies.

Travel on the road: does China's high-speed rail promote local tourism?

Following a Chinese saying: To be rich, roads first, high-speed rail (HSR) opening and station construction are indispensable for economic developing. Probing the nexus between HSR, as a vital part of modern transportation system, and local tourism development provides a scan for reviving tourism and gaining low-carbon transition after COVID-19 pandemic. Drawing on prefecture-level panel data, this study takes difference-in-difference and instrument variable methods to detect the overall and heterogeneous effects of HSR connection on cities' tourism development. The results showed that HSR connection had an overall positive effect on cities' domestic tourist arrivals. The heterogeneity of the effect from HSR to tourism development appears to be that central and western cities, non-resource-based cities, and small cities benefited more from the opening of HSR. From a dynamic perspective, HSR connection promoted local tourism development in the 0 and 1 year of HSR opening but failed to show a positive effect in the long term. Hence, the study proposed some adjustments for evaluating the efficiency of HSR with consideration for the tourism effect, redesigning the system of HSR with consideration for local heterogeneity, and optimizing the HSR environment. These measures can optimize China's HSR management and the design of HSR systems.

The Effects of Broadband Infrastructure on Carbon Emission Efficiency of Resource-Based Cities in China: A Quasi-Natural Experiment from the "Broadband China" Pilot Policy

Resource-based cities (RBCs) face serious environmental pollution, and there are efforts to try to overcome those challenges by transforming industrial structure through investing in new technologies. Based on the panel data of 114 prefecture-level resource-based cities in China, this paper uses the difference-in-differences (DID) method to identify the effects of the “Broadband China” pilot policy on the carbon emission efficiency of resource-based cities. The results show that the “Broadband China” pilot policy has a significant effect on the improvement of carbon emission efficiency of resource-based cities, and the results are still valid after parallel trend test, PSM-DID estimation and placebo test. This study also finds that there are differences in the carbon emission efficiency of different locations and types of resource-based cities. In addition, the results of the mechanism analysis show that the “Broadband China” pilot policy can promote the improvement of carbon emission efficiency by promoting the upgrading of the industrial structure, the accumulation of human capital and the improvement of the level of urban innovation of resource-based cities. The findings provide a reference for China’s resource-based cities to develop the Broadband infrastructure, realize industrial upgrading, accumulate human capital and improve urban innovation level, and promote low-carbon transformation and improve carbon emission efficiency.

Global research on the air quality status in response to the electrification of vehicles

Electric vehicles (EVs) can substantially decrease atmospheric pollutant emissions, thereby improving air quality, decreasing global warming, and improving human health. In this study, we performed a comprehensive bibliometric analysis using Web of Science to understand the research developments and future perspectives in EVs between 1974 and 2021. The analysis of indicators such as research trends, publication growth, and keywords revealed that most research in the selected timeframe was focused on applying and optimizing the existing technologies of different types of EVs to decrease air pollution and mortality. The changes in air quality owing to such electrification received special attention, with approximately 441 publications preferably in the English language. Among all the retrieved documents, research articles were most common (n = 295; 66.89% of the global output), dominated by the research domains of environmental sciences, followed by energy fuels and transportation science technology. Journal analysis revealed that Sustainability (n = 19, 4.30%) was the leading journal, followed by Journal of Cleaner Production and Science of the Total Environment. The most frequently used keywords were "electric vehicles," "air quality," and "air pollution." The most highly impactful article was published by Jacobson et al. (2005) in Science, with 620 total citations and 38.82 average annual citations. Furthermore, the United States (n = 118; 26.75% of the global output) had the highest publication rate, followed by China and the United Kingdom. The leading institutions were Tsinghua University (n = 16; 3.62% of the global research output) in China, followed by the University of Michigan and Cornell University in the United States. The current analysis warrants more focus on comprehensive analysis employing transport and chemistry modeling and using the latest technology for long life and sustainable batteries. This study provides a basis for future studies on improving air quality through innovative work in the electrification of vehicles.

Synergistic Air Pollutants and GHG Reduction Effect of Commercial Vehicle Electrification in Guangdong’s Public Service Sector

This paper aims to analyze the associated environment and climate benefits of electrification by comparing the air pollutant and CO2 emissions from the fuel cycle of battery electric commercial vehicles (BECVs) and internal combustion engine commercial vehicles (ICECVs) through a case study in Guangzhou Province. Five types of vehicles (i.e., electric buses, coaches, light-duty trucks, dump trucks, and waste haulers) used in the public service sector were selected for analysis, taking into account six development scenarios based on the prevalent ownership trends of electric vehicles and the energy system optimization process. The results reveal that an increase in commercial vehicle electrification in the public service sector will cause reductions of 19.3 × 103 tons, 0.5 × 103 tons, 9.5 × 103 tons, and 8.5 × 106 tons for NOx, PM2.5, VOCs, and CO2, respectively, from the base 2030 case (CS_II, the electrification rates of buses, coaches, light-duty trucks, dump trucks, and waste haulers will reach 100%, 26.5%, 15.4%, 24.0%, and 33.1%, and their power needs will be met by 24% coal, 18.4% gas, and 13.2% renewable power), but with a slight increase in SO2 emissions. With the further penetration of BECVs into the market, the emission reduction benefits for NOx, PM2.5, VOCs, and CO2 could be even more remarkable. Moreover, the benefit obtained from the optimization of the share of renewable energy is more noticeable for CO2 reduction than for air pollutant reduction. Prioritizing the electrification of light-duty trucks after completing bus electrification could be a potential solution for achieving ozone pollution control and lowering carbon emissions in Guangdong. In addition, these results can provide scientific support for the formulation or adjustment of advanced pollution mitigation and peaking carbon policies in Guangdong, as well as other regions of China.

A study on evaluation and influencing factors of carbon emission performance in China's new energy vehicle enterprises

Vehicle industry has made great contribution to human progress. However, in the process of vehicle operation, a large number of carbon compounds are emitted, which brings serious environmental problems. As one of the important means of vehicle carbon emission governance, the development of new energy vehicles (NEVs) has attracted much attention. The behavior and performance of NEV enterprises are highly concerned. Using Chinese 23 NEV vehicle enterprises' data from 2011 to 2018, this paper evaluates the carbon emission performance with the super-efficiency slacks-based measure (SE-SBM) model based on undesirable output and then constructs STIRPAT model to analyze the influencing factors of carbon emission performance. The results indicate that, firstly, the carbon emission performance of China's NEV enterprises is increasing year by year. Secondly, the carbon emission performance of different NEV enterprise is distinct in the same year, and the carbon emission performance of the same NEV enterprise is distinct in different year. Thirdly, technological innovation, government support, and free cash flow have significant positive impact on the carbon emission performance of NEV enterprises, while debt constraint, energy intensity, and enterprise size have a significant negative impact on the carbon emission performance of NEV enterprises.

Capital allocation efficiency, technological innovation and vehicle carbon emissions: Evidence from a panel threshold model of Chinese new energy vehicles enterprises

From the micro-enterprise level, this paper analyzes the relationship between the capital allocation efficiency of new energy vehicle enterprises and vehicle carbon emissions with technological innovation as the threshold variable. The results are as follows: Firstly, Whether R&D investment, R&D personnel input or patent is used to measure technological innovation, there is a double threshold effect between capital allocation efficiency and vehicle carbon emissions. When R&D investment intensity, R&D personnel input intensity or the ratio of patent number to R&D personnel is at a low level, the improvement of capital allocation efficiency will significantly increase vehicle carbon emissions. When the level of R&D investment intensity, R&D personnel input intensity or the ratio of patent number to R&D personnel exceeds the first threshold of 2.981, 13.7, 6.67, the promotion of capital allocation efficiency on vehicle carbon emissions will be weakened. When the level of R&D investment intensity, R&D personnel input intensity or the ratio of patent number to R&D personnel exceeds the higher threshold of 5.837, 19.6, 10.80, the positive externality of capital allocation efficiency is highlighted, which promotes the reduction of vehicle carbon emissions. Secondly, compared with R&D personnel input and patents, R&D investment has a greater impact on the relationship between capital allocation efficiency and vehicle carbon emissions. Thirdly, the technological innovation has a certain accumulation effect. Fourthly, government support and free cash flow will restrain vehicle carbon emissions, while energy intensity, debt constraint and enterprise size will increase vehicle carbon emissions.

Trend Analysis of Air Quality Index (AQI) and Greenhouse Gas (GHG) Emissions in Taiwan and Their Regulatory Countermeasures

A reduction in the energy-related emissions of air pollutants would not only mitigate climate change but would also improve local air quality and public health. This paper aimed to analyze the trends of air quality index (AQI) and greenhouse gas (GHG) emissions in Taiwan by using the latest official statistics. In addition, this study also summarized regulatory measures for controlling air pollution from the energy sector with relevance to sustainable development goals (SDGs). With the joint efforts by the public and private sectors, the change in the total GHG emissions did not vary much with the exception of 2009, ranging from 250 to 272 million metric tons of CO2 equivalent from 2005 through 2019. Based on the data on AQI, the percentage of AQI by station-day with AQI > 100 has decreased from 18.1% in 2017 to 10.1% in 2020, indicating a decreasing trend for all criteria air pollutants. On the other hand, the coronavirus disease (COVID-19) lockdown, in 2019, has positively impacted Taiwan’s urban air quality, which was consistent with those observed in other countries. This consistent situation could be attributed to the climate change mitigation policies and promotional actions under the revised Air Pollution Control Act and the Greenhouse Gas Reduction and Management Act of 2015. In response to the SDGs launched by the Taiwan government in 2018, achieving the relevant targets by 2030 can be prospective.

Electric vehicle-attributed environmental injustice: Pollutant transfer into regions with poor traffic accessibility

Electric vehicles (EVs) are promoted in recent years as an effective way in alleviating the air pollution caused by tailpipe emissions. However, the pollutants derived from EVs are unheeded. EVs rely on electricity to provide power, and thus their related pollution is transferred to the power plants, which gives rise to the environmental and health pressure to the adjacent regions. In this paper, the transfer of EV-attributed PM_2.5, SO₂, and NO_x inhalations in China are studied. Then by comparing the inhalations versus traffic accessibility among the impacted municipalities, this study sheds light on the environmental injustice lying in the mismatch between pollutant inhalations and traffic accessibility. The results reveal that compared with Shanghai and Shenzhen, the promotion of EVs in Beijing triggers higher pollutant inhalations to its surrounding municipalities. North China Power Grid undertakes 715.62 g PM_2.5 inhalation in total, which is 2.51 and 3.20 times higher than the East China Power Grid and the China Southern Power Grid, respectively. The number of municipalities with lower traffic accessibility while higher pollutant inhalation is 8,8, and 17 in North China Power Grid, East China Power Grid, and China Southern Power Grid respectively, indicating conspicuous environmental injustice resulted from the promotion of EVs.

Integrating Air Quality and Public Health Benefits in U.S. Decarbonization Strategies

Research on air quality and human health “co-benefits” from climate mitigation strategies represents a growing area of policy-relevant scholarship. Compared to other aspects of climate and energy policy evaluation, however, there are still relatively few of these co-benefits analyses. This sparsity reflects a historical disconnect between research quantifying energy and climate, and research dealing with air quality and health. The air quality co-benefits of climate, clean energy, and transportation electrification policies are typically assessed with models spanning social, physical, chemical, and biological systems. This review article summarizes studies to date and presents methods used for these interdisciplinary analyses. Studies in the peer-reviewed literature (n = 26) have evaluated carbon pricing, renewable portfolio standards, energy efficiency, renewable energy deployment, and clean transportation. A number of major findings have emerged from these studies: [1] decarbonization strategies can reduce air pollution disproportionally on the most polluted days; [2] renewable energy deployment and climate policies offer the highest health and economic benefits in regions with greater reliance on coal generation; [3] monetized air quality health co-benefits can offset costs of climate policy implementation; [4] monetized co-benefits typically exceed the levelized cost of electricity (LCOE) of renewable energies; [5] Electric vehicle (EV) adoption generally improves air quality on peak pollution days, but can result in ozone dis-benefits in urban centers due to the titration of ozone with nitrogen oxides. Drawing from these published studies, we review the state of knowledge on climate co-benefits to air quality and health, identifying opportunities for policy action and further research.

The inharmonious mechanism of CO2, NOx, SO2, and PM2.5 electric vehicle emission reductions in Northern China

Beijing benefits from the promotion of electric vehicles (EVs) in the improvement of road tailpipe emissions; these emissions are caused by internal combustion engine vehicles (ICEVs) and reduce the surrounding environmental quality. When analyzing the electricity grid, upstream emissions of EVs in Beijing can be tracked back to Shanxi and Inner Mongolia. This study investigates the inharmonious mechanism of emission reduction to promote EVs in Beijing and Northern China based on 6 scenarios and 42 real EVs. Because there is a neighbor effect, Beijing only accounts for 34%, 34%, 41%, and 35% of the total CO₂, NO_x, SO₂ and PM_2.5 emissions, respectively. Although the local CO₂, NO_x, and PM_2.5 emissions can be easily reduced (as long as the conversion of "coal to gas" plan is realized), it is difficult to achieve emission reductions of NO_x and SO₂ without increasing the clean electricity generation mix in Shanxi and Inner Mongolia at the total emission level. However, there is still a large reduction potential of EVs themselves due to an increasingly clean electricity mix in Beijing, Shanxi and Inner Mongolia. Beijing local CO₂, NO_x, SO₂ and PM_2.5 emissions can be reduced by 86.92%, 98.79%, 99.98% and 99.94%, respectively, and a total reduction of 78.43% of CO₂, 93.83% of NO_x, 97.85% of SO₂ and 99.26% of PM_2.5 emissions is possible. Compared with the corresponding ICEV, an EV of 18 kWh/100 km starts to reduce Beijing local CO₂, NO_x and PM_2.5 emissions in scenario 1, 3 and 1, respectively, while the SO₂ emissions cannot be reduced. However, the total CO₂, NO_x, SO₂ and PM_2.5 emissions can be reduced in scenario 2, 5, 5, and 1, respectively. A sensitivity analysis shows that the promotion of EVs can reduce Beijing local CO₂, NO_x, SO₂ and PM_2.5 emissions by 125.568-238.960 g/km, 0.059-0.113 g/km, -0.00003 - - 0.00007 g/km and 0.034-0.065 g/km, respectively. In addition, the total CO₂, NO_x, SO₂ and PM_2.5 reduction in emissions can be 132.883-253.757 g/km, 0.189-0.361 g/km, 0.299-0.569 g/km and 0.053-0.101 g/km, respectively.

Environmental and Economic Benefits of a Battery Electric Vehicle Powertrain with a Zinc–Air Range Extender in the Transition to Electric Vehicles

Emissions and pollution from the transportation sector due to the consumption of fossil fuels by conventional vehicles have been negatively affecting the global climate and public health. Electric vehicles (EVs) are a cleaner solution to reduce the emission and pollution caused by transportation. Lithium-ion (Li-ion) batteries are the main type of energy storage system used in EVs. The Li-ion battery pack must be considerably large to satisfy the requirement for the vehicle’s range, which also increases the cost of the vehicle. However, considering that most people use their vehicles for short-distance travel during daily commutes, the large pack is expensive, inefficient and unnecessary. In a previous paper, we proposed a novel EV powertrain design that incorporated the use of a zinc–air (Zn–air) battery pack as a range-extender, so that a smaller Li-ion pack could be used to save costs. The design and performance aspects of the powertrain were analyzed. In this study, the environmental and economic benefits of the proposed dual-battery powertrain are investigated. The results from the new powertrain were compared with values from a standard EV powertrain with one large Li-ion pack and a conventional internal combustion engine vehicle (ICEV) powertrain. In addition, an air pollution model is developed to determine the total amount of pollution released by the transportation sector on Highway 401 in Ontario, Canada. The model was then used to determine the effects of mass passenger EV rollout on pollution reduction.

Sustainability by High–Speed Rail: The Reduction Mechanisms of Transportation Infrastructure on Haze Pollution

Haze pollution impacts human health, as well as the competitive capabilities of firms and local economic development. Considerable attention has been given to the study of mechanisms for reducing haze pollution, but few studies have investigated the effect of city-to-city transportation infrastructures on environmental issues based on an institutional perspective. To address this research gap, this study advances our understanding by assessing the effect of city–to–city transportation on haze pollution caused by the operation of high-speed rail, which triggers the rapid flow of individuals and information, improves information transparency, as well as imposes institutional pressure on local governments and firms to reduce haze pollution. To further verify the underlying mechanisms, we tested the development of hard infrastructure (information communication technology) and soft infrastructure (market development level), which represent two conditions for which the mechanism is likely to be critical. We tested our hypotheses using a sample of 288 prefecture-level cities in China during the period from 2005 to 2016. The empirical results indicate that the operation of high-speed rail can reduce haze pollution by 17% on average.

Air Quality Strategies and Technologies: A Rapid Review of the International Evidence

Poor air quality is a pressing policy issue that spans public health and environmental portfolios, and governments worldwide are investing in a wide array of measures to address it. This paper is a rapid review of the evidence behind air quality strategies and technologies. It was conducted according to the principles of a systematic review, and includes both academic and “grey” literature sources. It focuses on road transport in urban areas, because air pollution tends to be worse in cities, and the main source is fossil fuel vehicles. It draws on the environmental science and policy literature to provide interdisciplinary insight into the most effective air quality policy measures. The most promising initiatives include active travel infrastructure, roadside barriers, low emission zones, and low speed limits. Technologies which remove pollution from the air largely remain unproven, especially at the scale needed to make a significant impact. The combinations of policies from three cities which rank highly for air quality are reviewed; one important finding is that policies are most effective when they are a part of a mutually reinforcing suite of measures. Policies consistent across the cities studied are good public transport coverage, a good cycle network, and financial incentives for electric vehicle purchase.

The aggravation of urban air quality deterioration due to urbanization, transportation and economic development - Panel models with marginal effect analyses across China

In this paper, panel data models are established to examine the impacts of urban construction, transport facilities, and economic development on the urban air quality. Combined with data from different tiers of Chinese cities for two time series, 2010 and 2015, the variable-intercept model (VIM) is used to determine the parameters and significance of each independent variable. The marginal effects of different categories of independent variables (urbanization, transportation and economy) on the urban air quality are also studied with regard to the results of different VIMs. The results show that transportation factors (such as annual passenger trips, bus numbers and taxi numbers) have the most significant effects on the air quality for all the Chinese cities. Moreover, urbanized area and annual gross value of industrial output also have prominent impacts on the air quality across China. In addition, the marginal effects of the air quality index obtained via VIMs with classified local variables reflect that the influences of urbanization, transportation and economy on urban air quality are substantially different among different tiers of cities. Therefore, based on the findings, we propose measures to improve air quality for different tiers of cities, such as rational use of space resources, optimizing transport modes, and encouraging carpooling.

An interval-possibilistic basic-flexible programming method for air quality management of municipal energy system through introducing electric vehicles

Contradictions of sustainable transportation development and environmental issues have been aggravated significantly and been one of the major concerns for energy systems planning and management. A heavy emphasis is placed on stimulation of electric vehicles (EVs) to handle these problems associated with various complexities and uncertainties in municipal energy system (MES). In this study, an interval-possibilistic basic-flexible programming (IPBFP) method is proposed for planning MES of Qingdao, where uncertainties expressed as interval-flexible variables and interval-possibilistic parameters can be effectively reflected. Support vector regression (SVR) is used for predicting electricity demand of the city under various scenarios. Solutions of EVs stimulation levels and satisfaction levels in association with flexible constraints and predetermined necessity degrees are analyzed, which can help identify the optimized energy-supply patterns that could plunk for improvement of air quality and hedge against violation of soft constraints. Results disclose that largely developing EVs can help facilitate the city's energy system with an environment-effective way. However, compared to the rapid growth of transportation, the EVs' contribution of improving the city's air quality is limited. It is desired that, to achieve an environmentally sustainable MES, more concerns should be focused on the integration of increasing renewable energy resources, stimulating EVs as well as improving energy transmission, transport and storage.

Assessing the Future Vehicle Fleet Electrification: The Impacts on Regional and Urban Air Quality

There have been significant advancements in electric vehicles (EVs) in recent years. However, the different changing patterns in emissions at upstream and on-road stages and complex atmospheric chemistry of pollutants lead to uncertainty in the air quality benefits from fleet electrification. This study considers the Yangtze River Delta (YRD) region in China to investigate whether EVs can improve future air quality. The Community Multiscale Air Quality model enhanced by the two-dimensional volatility basis set module is applied to simulate the temporally, spatially, and chemically resolved changes in PM_2.5 concentrations and the changes of other pollutants from fleet electrification. A probable scenario (Scenario EV1) with 20% of private light-duty passenger vehicles and 80% of commercial passenger vehicles (e.g., taxis and buses) electrified can reduce average PM_2.5 concentrations by 0.4 to 1.1 μg m^-3 during four representative months for all urban areas of YRD in 2030. The seasonal distinctions of the air quality impacts with respect to concentration reductions in key aerosol components are also identified. For example, the PM_2.5 reduction in January is mainly attributed to the nitrate reduction, whereas the secondary organic aerosol reduction is another essential contributor in August. EVs can also effectively assist in mitigating NO₂ concentrations, which would gain greater reductions for traffic-dense urban areas (e.g., Shanghai). This paper reveals that the fleet electrification in the YRD region could generally play a positive role in improving regional and urban air quality.

Impacts of compact growth and electric vehicles on future air quality and urban exposures may be mixed

'Smart' growth and electric vehicles are potential solutions to the negative impacts of worldwide urbanization on air pollution and health. However, the effects of planning strategies on distinct types of pollutants, and on human exposures, remain understudied. The goal of this work was to investigate the potential impacts of alternative urban designs for the area around Tampa, Florida USA, on emissions, ambient concentrations, and exposures to oxides of nitrogen (NO_x), 1,3-butadiene, and benzene. We studied three potential future scenarios: sprawling growth, compact growth, and 100% vehicle fleet electrification with compact growth. We projected emissions in the seven-county region to 2050 based on One Bay regional visioning plan data. We estimated pollutant concentrations in the county that contains Tampa using the CALPUFF dispersion model. We applied residential population projections to forecast acute (highest hour) and chronic (annual average) exposure. The compact scenario was projected to result in lower regional emissions of all pollutants than sprawl, with differences of -18%, -3%, and -14% for NO_x, butadiene, and benzene, respectively. Within Hillsborough County, the compact form also had lower emissions, concentrations, and exposures than sprawl for NO_x (-16%/-5% for acute/chronic exposures, respectively), but higher exposures for butadiene (+41%/+30%) and benzene (+21%/+9%). The addition of complete vehicle fleet electrification to the compact scenario mitigated these in-county increases for the latter pollutants, lowering predicted exposures to butadiene (-25%/-39%) and benzene (-5%/-19%), but also resulted in higher exposures to NO_x (+81%/+30%) due to increased demand on power plants. These results suggest that compact forms may have mixed impacts on exposures and health. 'Smart' urban designs should consider multiple pollutants and the diverse mix of pollutant sources. Cleaner power generation will also likely be needed to support aggressive adoption of electric vehicles.