Environmental Impacts of Road Vehicles

Past, Present and Future

R M Harrison, R E Hester

• Publisher: Royal Society of Chemistry
• Year: 2017
• Print ISBN: 9781782628927
• eBook ISBN: 9781788011761
• Edition: 1
• Topic: Technology & Engineering
• Subtopic: Environmental Science
• Index: Technology & Engineering

The first concerns that come to mind in relation to pollution from road vehicles are direct emissions of carbon dioxide and toxic air pollutants. These are, of course, important but the impacts of road traffic are altogether more substantial. This volume of the Issues in Environmental Science and Technology Series takes a broader view of the effects on the environment and human health, excluding only injury due to road traffic accidents. By looking across the environmental media, air, water and soil, and taking account also of noise pollution, the volume addresses far more than the conventional atmospheric issues. More importantly, however, it examines present and future vehicle technologies, the implications of more extensive use of batteries in electric vehicles and the consequences of recycling vehicles at the end of use. Finally, examples of life-cycle analysis as applied to road vehicles are reviewed. This book is a comprehensive source of authoritative information for students studying pollution, and for policy-makers concerned with vehicle emissions and road traffic impacts more generally.

Local-acting Air Pollutant Emissions from Road Vehicles

QINGYANG LIU AND JAMES J. SCHAUER^*

ABSTRACT

This chapter reviews the local impacts of air pollution emissions from roadways on air quality, human health, and the natural and built environments. These impacts are a global issue affecting urban areas around the world, including developed and developing nations, emphasizing the need to reduce emissions from roadway transport sectors around the world. Air pollutants emitted from vehicles, including particulate matter, nitrogen oxides, carbon monoxide, and hydrocarbons, are reactive (i.e. they have larger impacts on human health per unit of emissions compared to many other air pollution sources due to the proximity of the emissions and the chemical and physical natures of the emissions). These impacts affect public health, visibility, material damage, the surrounding ecosystems, and the quality of life for populations living near roadways. Although roadway emissions vary from region to region depending on the state of local fuel quality, vehicle technology, and emissions standards, general trends of roadway emissions and roadway impacts are summarized in this chapter. This summary includes the chemical composition of emissions from roadways, the contribution of mobile sources to local and regional air quality, the impacts on cultural heritage, and the health impacts of mobile sources. Existing regulations and projected trends in national standards for vehicle emissions are discussed and the implications of roadways for local environments are considered.

1 Introduction

Air pollution is the leading environmental health risk factor for disease in developing and developed countries.¹ A 2010 Health Effects Institute report suggests that 3.2 million premature deaths are caused by outdoor air pollution, which includes the impacts of roadways.² Vehicle emissions can be divided into either tailpipe emissions or non-tailpipe emissions. Non-tailpipe emissions include road wear, brake wear, tire wear, fugitive emissions of fuel leakage, evaporative emissions of fuel, and the resuspension of road dust. Tailpipe emissions include particulate matter (PM) and gaseous emissions, such as nitrogen oxides (NO_x), sulfur dioxide (SO₂), carbon monoxide (NO), and volatile organic compounds (VOCs).³ PM consists of a fine particle fraction (PM_2.5), which is defined as particles having an aerodynamic diameter of less than 2.5 µm, and a coarse fraction (PM₁₀), which is particles with diameters ranging between 2.5 and 10 µm. Both particle fractions (PM_2.5 and PM₁₀) contain toxic components such as polycyclic aromatic hydrocarbons (PAHs) and transition metals.^4–7

Laboratory experiments have shown that gaseous organic compounds in both gasoline engine (spark ignition [SI]) and diesel engine exhaust (compression ignition [CI]) can form secondary organic aerosols (SOAs) and photochemical smog, including ozone (O₃).⁸ Older diesel engines that do not have after-treatment technologies produce significant amounts of NO_x and soot pollutants compared to modern diesel and gasoline engines with effective emission controls.^7,9 Thus, growing concerns about the impacts of transport emissions on air quality have resulted in the implementation of strict emission regulations in many economically developed countries, such as the USA, Japan, and some Western European countries, staring in the mid-1970s for gasoline engines and the 2000s for diesel engines.^10,11 To address vehicle emissions in countries with extreme air pollution and countries that are rapidly developing, these emission control technologies are becoming more widely used around the world.

Despite great improvements in the technology of exhaust reductions for modern vehicles, global road emissions are projected to increase over the next 30 years due to the expected growth in vehicle ownership worldwide (i.e. between 2 and 3 billion vehicles by 2050).^12,13 An improved understanding of various aspects of road emissions, including chemical characteristics, source contributions, and other associated impacts, is therefore vital for policy makers working to implement updated traffic emission standards.^14,15

This review presents a global perspective on the local impacts of roadway emissions. Section 2 of this chapter focuses on the changes in road emissions due to developing technology and addresses both tailpipe and non-tailpipe emissions. The review focuses on pollutants from mobile sources that have significant local impacts. Section 3 of the report focuses on key pollutants emitted from roadways that undergo chemical and physical transformations as they transport across the urban scale, with an emphasis on air toxics. Section 4 provides the latest epidemiological evidence for mobile source impacts and discusses the differences and linkages between health impacts of proximal road exposures and exposures to mobile sources as components of the urban air pollution mixture. This section also covers recent studies of the contributions of mobile sources to PM and O₃ in cities around the world. Section 5 of the report summarizes several case studies of the effects of mobile source emissions on the deterioration of historical heritage sites and their influence on the air pollution-derived discoloration of the built environment. Section 6 of the report summarizes the impacts of mobile sources on regional air quality and presents data from around the world. Section 7 presents a summary of recent mobile source emission trends, including a comparison between emissions in developed and developing countries and their underlying differences resulting from fossil fuel quality and vehicle technology. Finally, Section 8 summarizes the current regulatory requirements for emission reductions around the world and the projected trends for the coming decades.

2 Fuel Type, Fuel Quality, and Vehicle Technology

Vehicle emissions are composed of a range of chemical pollutants including PM, carbon monoxide (CO), carbon dioxide (CO₂), N...

Table of contents

• Cover
• Title
• Copyright
• Preface
• Contents
• Editors
• Road Vehicle Technologies and Fuels
• Gaseous and Particle Greenhouse Emissions from Road Transport
• Local-acting Air Pollutant Emissions from Road Vehicles
• Water and Soil Pollution Implications of Road Traffic
• Cardiovascular Health Effects of Road Traffic Noise
• Environmental Impact of Hybrid and Electric Vehicles
• Development Implications for Malaysia: Hydrogen as a Road Transport Fuel
• Latest Trends and New Challenges in End-of-life Vehicle Recycling
• Life Cycle Assessment of Road Vehicles
• Subject Index