SESSION II: ADVANCES IN AUTOMOTIVE AND OTHER TRANSPORT TECHNOLOGIES

Dr. Wm. A.Wulf, president of the NAE, moderated the second session. The session focused on the experience of the United States and other nations in dealing with the growth of the automobile industry.

Lessons learned on the road to more efficient transport systems—Martin Wachs, University of California, Berkeley

Wachs said that today in the United States there are about 770 automobiles per 1,000 people. That means we literally could have every man, woman, and child on the road at the same time, and still have room in the back seats for their pets and baggage. The rate of increase in automobiles per capita in the United States is now very low and finally approaching saturation, though vehicle miles of driving per capita is still increasing.

In China, in 1998 there was around one personal vehicle per 90 persons, up from one per 200 persons in 1995. The United States had one vehicle per 90 persons around the year 1910, but Chinese growth in automobiles will clearly be more rapid than the United States—already the estimate for 2000 is one vehicle per 70 persons. China has the benefit of being able to adapt knowledge, technology, and management strategies that many other countries have perfected over the last 95 years, though rapid motorization will be demanding and disruptive even given China’s ability to leap-frog over several stages of development. It is important to observe the policies that worked well and those that failed.

Wachs said the automobile has influenced American life as profoundly as any device in history, but it is not alone. Other technologies like the telephone, radio, television, and other telecommunications also have had profound effects. Also, the impact of the automobile on the interactions among people was matched by the effect of the motor truck on the movement of goods. The effects of all these innovations were complementary and additive. In the United States, the full adaptive process took around 100 years, and in China it will take place in a much shorter time.

Wachs said there are five major themes to consider:

  1. The automobile as a fundamental element of the economy. One worker in six finds automobiles and trucks the source of their employment: building, repairing, driving professionally, insuring, licensing, testing, building and maintaining highways, etc. This fact has a large political impact in the United States, affecting the economy and foreign policy. A change in the world price of petroleum can throw the U.S. economy into recession, and our intense interest in the Middle East and our rejection of the Kyoto accords are direct results of this fact. The entire U.S. trade deficit with respect to balance of payments with other countries is accounted for by our imports of petroleum for transportation. Creating an automotive industry involves far more than building and selling cars; it changes the entire economic and employment structure of the nation.

  2. The importance of roads and highways and parking and infrastructure in support of the automobile and truck. In United States cities today, 30 percent of the land area is devoted to



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The Future of Personal Transport in China: Summary of a Symposium, January 12, 2001 SESSION II: ADVANCES IN AUTOMOTIVE AND OTHER TRANSPORT TECHNOLOGIES Dr. Wm. A.Wulf, president of the NAE, moderated the second session. The session focused on the experience of the United States and other nations in dealing with the growth of the automobile industry. Lessons learned on the road to more efficient transport systems—Martin Wachs, University of California, Berkeley Wachs said that today in the United States there are about 770 automobiles per 1,000 people. That means we literally could have every man, woman, and child on the road at the same time, and still have room in the back seats for their pets and baggage. The rate of increase in automobiles per capita in the United States is now very low and finally approaching saturation, though vehicle miles of driving per capita is still increasing. In China, in 1998 there was around one personal vehicle per 90 persons, up from one per 200 persons in 1995. The United States had one vehicle per 90 persons around the year 1910, but Chinese growth in automobiles will clearly be more rapid than the United States—already the estimate for 2000 is one vehicle per 70 persons. China has the benefit of being able to adapt knowledge, technology, and management strategies that many other countries have perfected over the last 95 years, though rapid motorization will be demanding and disruptive even given China’s ability to leap-frog over several stages of development. It is important to observe the policies that worked well and those that failed. Wachs said the automobile has influenced American life as profoundly as any device in history, but it is not alone. Other technologies like the telephone, radio, television, and other telecommunications also have had profound effects. Also, the impact of the automobile on the interactions among people was matched by the effect of the motor truck on the movement of goods. The effects of all these innovations were complementary and additive. In the United States, the full adaptive process took around 100 years, and in China it will take place in a much shorter time. Wachs said there are five major themes to consider: The automobile as a fundamental element of the economy. One worker in six finds automobiles and trucks the source of their employment: building, repairing, driving professionally, insuring, licensing, testing, building and maintaining highways, etc. This fact has a large political impact in the United States, affecting the economy and foreign policy. A change in the world price of petroleum can throw the U.S. economy into recession, and our intense interest in the Middle East and our rejection of the Kyoto accords are direct results of this fact. The entire U.S. trade deficit with respect to balance of payments with other countries is accounted for by our imports of petroleum for transportation. Creating an automotive industry involves far more than building and selling cars; it changes the entire economic and employment structure of the nation. The importance of roads and highways and parking and infrastructure in support of the automobile and truck. In United States cities today, 30 percent of the land area is devoted to

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The Future of Personal Transport in China: Summary of a Symposium, January 12, 2001 streets and highways, and parking area comprises another 10 percent. Ninety five percent of this area constitutes local streets and rural roads that carry 5 percent of the traffic, and 5 percent of the area is dedicated to highways and freeways that carry 95 percent of the traffic. These two types of roads are financed in very different ways. The local streets and roads that provide access to property are paid for from local property taxes and local sales taxes. The other five percent of roads is financed by user fees in the form of gas taxes or tolls. This has been very successful because it provides more money as traffic increases, and that money is used exclusively to build and maintain the roads. There is far less competition for resources than would be the case if government were to pay for roads out of general funds. The environmental impacts of the automobile. The automobile has had a mixed effect on health. Access to health care facilitated by the automobile is one of the most important variables for increasing life expectancy. But air pollution caused by exhaust emissions and water pollution caused by runoff from roads have had a negative effect, and disposal of old automobiles, tires, parts and motor oil cause additional environmental problems. But over the past few decades, enormous progress has been made, mostly through new technologies, and the United States is on its way toward creating a sustainable transportation system. Relationships between mobility or travel and urban form. The automobile has profoundly affected the form of cities. Earlier, city population densities were much higher, with resulting disease, fires, accidents, and other disasters. Public transit, the automobile, the creation of suburbs, and decentralization have lowered the densities and made the cities much more livable. Now this solution has given rise to new problems—sprawl, congestion, energy waste, pollution and even racial Segregation—and proposed solutions include a return to higher densities in the urban centers. However, it is now politically more difficult to redesign the cities, and only a few places, like Portland, Oregon, have been able to make significant gains in this direction. The impact of the transportation system on the distribution of well-being in society. Modern land use patterns are designed with the automobile as part of the system, and those who have no cars (the elderly, poor, minorities, and the disabled) are left out of some benefits. Automobiles also cause 41,000 deaths a year in the United States, including pedestrians and cyclists, more than all the wars in its history. It is the leading cause of death for those under 35 years of age. Important improvements have been made in vehicle design, seat belts, etc., but there has been less progress in traffic management. Some of the proposed innovations in this area involve applications of information technology to control traffic flow and charge for road use. Wachs concluded by stating that in the United States, automobile use has had a generally beneficial effect on society. However, urban design and community planning has not been sufficiently sophisticated in coping with the automobile. Automobile users should be charged a greater proportion of the full social costs of their travel, and other modes of travel, like cycling, walking and transit need to be treated more fairly in transportation planning. While adequate roads and parking facilities should be provided, those who benefit from them should pay their full social costs, with due regard for the needs for sidewalks, bicycle paths, and transit facilities. It is possible to integrate urban transit and pedestrian facilities safely and economically with streets and highways and to protect urban parks, waterfronts, landmarks, and tourist attractions from being overrun by parked cars. Much of the criticism aimed at the automobile itself should be directed at the poor urban design decisions that have been the root of many of the inequities that characterize mobility in urban areas.

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The Future of Personal Transport in China: Summary of a Symposium, January 12, 2001 New developments in engines, fuels; emission controls, and the role of electronics—John Heywood, Massachusetts Institute of Technology (MIT) Heywood stated the major vehicle-related social, economic, and environmental issues are urban and regional air pollution, energy consumption by source, greenhouse gas emissions, noise, and safety. The technology options available to address these problems in the future include: Improved mainstream technologies For vehicle structure: better conventional materials (e.g. high strength steel), reduction of weight, lower drag resistance For the engine: higher power and volume, improved efficiency, lighter weight For the transmission: more gears (automatic/manual, continuous variable) For fuel: cleaner gasoline and diesel Available alternative technologies For vehicle structure: lightweight materials (e.g. aluminum, magnesium), lowest drag designs For the power train: hybrids (engine plus energy storage) and fuel cells (hydrogen fueled, or liquid fueled with reformer) For fuels: natural gas, biomass (alcohol), and hydrogen. Table 1 compares spark-ignition and diesel engines: TABLE 1—Spark-Ignition Engine Compared with Diesel   Power Density Efficiency Cost Density Emissions Fuel Spark-Ignition Engine Good Lower Low Effective catalyst technologies Low cost; knock resistant Diesel: Naturally Aspirated Lower High Higher Catalyst technologies Lowest cost; high sulfur Diesel: Turbo-charged Higher Higher Higher Not Available* Aromatics *Selective catalytic reduction effective with large stationary engines. The gasoline engine is not as efficient, but there is no emissions treatment available for the diesel engine which uses cheaper fuels but has a higher initial cost. Heywood noted that engine efficiency has been improving almost linearly over time as a result of incremental innovation. Toyota and Honda have been the leaders in engine innovation, while the

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The Future of Personal Transport in China: Summary of a Symposium, January 12, 2001 U.S. has been better in innovating the manufacturing process. In a recent MIT study, “On the Road in 2020: Life Cycle Analysis,” technological options for the year 2020 are assessed and compared. The study can be seen at http://web.mit.edu/energylab/www/. A sample of the results are shown in Table 2 below. He said this discussion can be summarized in four points. Sizeable improvements in internal combustion engine performance and efficiency are feasible, on the order of one percent per year, over the next two decades. If engine, transmission, and vehicle performance are considered together, long term total energy consumption improvement may be as large as a factor of two. The effect of alternative fuels on engine performance, energy and emissions will be modest, except for hydrogen. Total system (“well to wheels”) energy and CO2 emissions for the best internal combustion engine and fuel cell-based systems are similar in magnitude. Table 2 Peformance Potential in 2020 Propulsion system Advanced vehicle below Date Vehicle gas equiv. mpg Total system Energy use MJ/km Total system CO2 gC/km Price increase $ Gasoline ICE present 28 3.6 72 0 Evolving Baseline ICE/Vehicle 2020 43 2.3 47 800 Gas, ICE, Adv. Vehicle 2020 49 2.1 42 2200 Diesel, ICE, Adv. Vehicle 2020 56 1.8 37 3300 Gas, hybrid ICE, Adv. Vehicle 2020 71 1.5 30 4400 CNG, hybrid ICE, Adv. Vehicle 2020 73 1.5 24 4500 H2 fuel cell hybrid, Natural Gas 2020 94 1.7 34 5000 Gas reformer fuel cell hybrid 2020 42 2.4 49 6200 Status of the Partnership for a New Generation Vehicle (PNGV)—Trevor O.Jones, Biomec, Inc. Jones said that in 1993, President Clinton and the chief executive officers of the three major U.S. automobile companies announced PNGV. The private-public partnership was to carry out the research and development necessary to produce a midsize vehicle at a current affordable price that

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The Future of Personal Transport in China: Summary of a Symposium, January 12, 2001 would get eighty miles per gallon and conform to the emissions standards in force at that time. The target date for the concept cars was 2000 and for the vehicle itself 2004. The NRC was asked to form a committee to peer review the research and assess the technology choice. In terms of collaboration, the partnership as such was successful. Around one billion dollars was contributed annually by industry and $300 million by the government. Jones asked: why is a PNGV needed? There is continuing global increase in population, and a parallel increase in the vehicle population. At the same time, the fuel economy is not improving, which will eventually put pressure on a finite petroleum fuel reserve. (By 2015, it is projected that there will be one billion vehicles in use with a fuel consumption of 10 billion barrels per year.) Global greenhouse gas emissions are increasing. The cost of importing oil to the United States is a national security concern. Further, it was believed that the joint development of the new generation vehicle would enhance the competitiveness of the U.S. automotive industry. The economy of the new car fleet is improving because of adherence to corporate average fuel economy (CAFE) standards, first passed by Congress in 1975. In 1992, an NRC study on technically achievable fuel economies had predicted up to 37 mpg for midsize cars by 2006 on the basis of current progress, far from the PNGV targets. A radical change in technology was needed to achieve greater efficiency. The PNGV program has three discrete goals: Significantly improve national competitiveness in manufacturing for future generations of vehicles. Implement commercially viable innovations from ongoing research on conventional vehicles. Develop vehicles to achieve up to three times the fuel efficiency of comparable 1994 family sedans, or 80 mpg. Many parts of the U.S. government became involved, including the national laboratories. Many universities became involved, and on the industry side, many suppliers participated. Overall, 300 institutional participants became involved. The U.S. Council for Automotive Research (USCAR), was to coordinate the efforts of the big three auto manufacturers. The Under Secretary for Technology, U.S. Department of Commerce, was appointed by the President to coordinate the federal government’s participation. The PNGV program began by analyzing the energy distributions in all functions of an automobile, from engines to accessories. The objective was to make major improvements in all powertrain and vehicle characteristics. Typical objectives were to double thermal efficiency, reduce weight by 10 to 40 percent, capture 50 to 70 percent of braking energy, reduce drag by 20 percent, reduce rolling resistance by 20 percent, and lower accessory loads by 30 percent. The major areas of development were hybrid electric systems, fuel cell-electric powertrains, energy storage by flywheel and battery, light weight material, drag reduction, and lower rolling resistant tires. It was soon realized that the gasoline engine and the electric vehicle programs would be unable to meet the timetables. With its weight reduced by nearly 50 percent, only the direct injection diesel hybrid made the cut for 80 mpg. All concept cars unveiled in 2000 were lightweight direct injection diesel hybrids with nickel metal hydride or lithium ion batteries. Jones said issues for the next phase of the PNGV are:

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The Future of Personal Transport in China: Summary of a Symposium, January 12, 2001 The added cost of a hybrid powertrain—nearly $7,500 over today’s vehicles The added cost of lightweight materials over steel The added cost of a compression ignition, direct injection, or CIDI (diesel) fuel injection system The control and reduction of NOx and particulate matter Development of low cost and low weight energy storage systems Availability of low sulfur fuels. Jones noted that for the long term, the fuel cell hybrid is promising. Problems include the cost, size, and weight of energy converters with reformer, the start-up time and transit response, overall efficiency with the reformer, low vehicle range with stored hydrogen, and the availability of a hydrogen fuel infrastructure. The PNGV program has demonstrated the integration of cultures among the government, the universities, and USCAR. Of the three vehicles themselves, only the General Motors car has met the fuel efficiency goal for gasoline equivalent. The emissions standards, which have become more stringent since 1993, have not yet been met. Actions on Urban Transportation Problems: Possibilities for China—Ralph Gakenheimer, Massachusetts Institute of Technology (MIT) Gakenheimer said that rapid motorization in China is becoming an incontrovertible fact, and it is clear that it is in the interest of Chinese industry to help municipalities lighten the burden of congestion by better planning and traffic management. It will be useful to examine the experience of other rapidly motorizing cities around the world. The parameters that define the problem faced by urban areas are the time evolution of the increase in the proportion of automobile trip making and its rate of acceleration, the percentage and distribution of local automobile ownership, changes in urban structure, and the existence and reach of subways and other forms of public mass transportation. Some of the most instructive experiences in other parts of the world have been: Evolution of modal shares under rapid motorization. Some of the interesting data come from Santiago, Chile, where as the number of autos grew by 50 percent between 1977 and 1991, the share of trips by auto grew by 61 percent and the trips per capita by 86 percent. The biggest decline in mode share was in buses, while subways and walking increased. However buses are still the dominant mode for commuting to work. The use of light rail in Quito, Ecuador. Single articulated trolley-buses, operated at low cost, have become popular. The break-even fare is U.S.$0.27 per ride. Public transportation and restricted areas in Curitiba, Brazil. Corridors of development were planned along the lines of the mass transit system. Curitiba boasts a modern bus system, coordinated with traffic control systems, with wide bus doors and prepayment stations. It has helped to control the development of the city, and the population density is declining. The collaboration of government agencies in Houston, Texas. Houston covers a large area with an overall density of two persons per hectare. There are 55 separate subsystems of the regional

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The Future of Personal Transport in China: Summary of a Symposium, January 12, 2001 transportation system, from traffic signal control to tollway management, railroad crossings, and emergency management systems. An “intelligent transport system” has been developed through a consortium among different municipal agencies called TRANSTAR. It is based on agreement among the participating agencies that action is necessary for planning and congestion relief. In the new system, traffic is controlled from a single room by staff seconded by all agencies. Licensing and vehicle access restrictions in Singapore. Singapore has established electronic licensing, and no vehicle may enter the central city during rush hour without a costly license. This system has been supplemented by electronic road pricing, with automatic charges through a debit card located in the vehicle. The result has been lower revenue, but flexible management of traffic, reduced numbers of downtown entries, and traffic speeds increasing to 45 km per hour. Automobile traffic management in Bogota, Colombia. Bogota, it seems, is trying several options. There are “no drive” days, in which 40 percent of the vehicles rest each day. This has reduced congestion, numbers of accidents, and air contamination, and it has increased the flexibility of traffic scheduling. A subway was proposed by the national government, but the mayor chose the Curitiba system of buses instead. Gakenheimer said the shared goal of the municipality and car owner to reduce congestion, buses should not be seen as the enemy of car sales. Health implications of increased motorized transport—Dan Greenbaum, Health Effects Institute (HEI) Greenbaum said that concerns about ambient air pollution and public health first rose to broad public attention in the 1950’s, following significant air pollution episodes in London, England, Donorra, Pennsylvania, and elsewhere, that were linked to noticeable increases in hospitalization and premature mortality. These incidents, which involved air pollution largely from industrial sources and home heating, presaged public policy action for the past four decades to reduce air pollution and improve public health. Increasingly during that time, as vehicle travel has grown dramatically, attention has focussed on air pollution from transport and its impacts on human health. Beginning in the 1970s in the United States and in the 1980s in Europe, there has been substantial progress to reduce the emissions from individual vehicles, and, more recently, to make improvements in the quality of fuel that have resulted in reductions of some emissions by greater than 90 percent. Meanwhile, traffic volume has grown substantially, offsetting much of the improvement achieved. Also, scientific knowledge has increased, with scientists finding health effects from vehicle emissions at lower levels of exposure. Thus there has been, and there continues to be, significant public attention to reducing the emissions from vehicles and fuels and their attendant effects on human health. Greenbaum said that since 1980, HEI has been producing extensive research on the health effects of air pollution from motor vehicles and other sources. He said HEI had learned much during that time about the emissions from vehicles, personal exposure to those emissions, and the resulting effects. Greenbaum said his paper attempts to review briefly what we know about emissions, exposure and effects, and to discuss current and likely future trends.

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The Future of Personal Transport in China: Summary of a Symposium, January 12, 2001 Emissions. The combustion of petrol (gasoline) and diesel fuel in vehicle engines produces a number of emissions of potentially harmful substances. These emissions are not solely the result of the combustion process, nor do they come only from the tailpipe of the vehicle. Evaporative emissions—from refueling, leaks in the fuel system and engine, etc.—can equal emissions from the tailpipe. The emissions from motor vehicles come in two primary forms: major gaseous and particulate air pollutants, which can be found in relatively high amounts in the atmosphere, and air toxins which usually are found in lower amounts in the atmosphere but can have important health impacts. The gaseous and particulate pollutants to which motor vehicles contribute include carbon monoxide, H2O2 and ozone (through their atmospheric precursors volatile organic compounds [VOCs] and nitrogen oxides [NOx]), fine particulate matter PM10 and PM2.5 (particles smaller than 10 and 2.5 microns in aerodynamic diameter respectively), and nitrogen dioxide. The air toxins emitted from motor vehicles include aldehydes (acetaldehyde, formaldehyde, and others), benzene, 1,3-butadiene, and a large number of substances known as polycyclic organic matter (including polycyclic aromatic hydrocarbons, or PAHs). All of the types of emissions from motor vehicles also come from other sources, such as industrial processes, electric power generation, and home heating. As a result, the contribution of motor vehicles to ambient levels depends on the pollutant. In most cases, motor vehicles contribute between 25 percent and 40 percent of the ambient levels, although in a few cases (e.g. carbon monoxide, ultrafine particles (PM0.1), and 1,3-butadiene) motor vehicle contributions are noticeably higher. Exposure and Effects. While, in general, motor vehicles contribute a significant portion, although not the majority, of most air pollutants, there are certain circumstances in which motor vehicles can contribute a substantially higher amount to personal exposure. In particular, in urban centers, along roadsides, and especially in urban street canyons in crowded business districts, mobile source contributions can contribute 2 to 10 times as much as the general background. Research over the past several decades has found a variety of effects from the different pollutants, including effects on the respiratory, neurologic, and cardiac systems, and the promotion of several different types of cancer. One of the challenges of understanding these effects is that they are usually the result of a complex mixture of pollutants, and it is often difficult to disentangle the specific effects of one pollutant from the effects of other pollutants that follow similar spatial and atmospheric patterns. At the same time, it is apparent that not all members of the population are equally sensitive to such effects, and that some subgroups (e.g. the elderly, asthmatics, children, people with heart disease) may be at more risk from exposure to air pollution. Overall, the effects of these pollutants on public health tend to be relatively small in comparison with other risk factors such as cigarette smoking, but because of the large number of people exposed the effects are of public concern. Formal analyses of these overall effects are limited by ability to accurately estimate exposure and to calculate the risk per unit exposure. Within these limitations, one recent European analysis estimated that approximately six percent of mortality (40,000 deaths annually) in three European countries (France, Austria, and Switzerland) could be attributed to air pollution, about half of that due to exposure to emissions from vehicles. Despite some uncertainties, there is much known about the effects of carbon monoxide, ozone, particulate matter, and air toxins:: Carbon monoxide is a gas emitted directly from vehicles. When inhaled it replaces oxygen in the bloodstream, forming carboxyhemoglobin and interfering with the normal transport of oxygen to the heart and brain. High levels of exposure are known to be lethal; low levels found

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The Future of Personal Transport in China: Summary of a Symposium, January 12, 2001 in ambient settings are not likely to have effects in healthy individuals but can advance the time of angina (chest pain) in people with coronary artery disease and may cause increased incidence of cardiac effects. Some recent epidemiologic studies have found relationships between increased CO levels and increases in mortality and morbidity. Ozone is a gas formed in the atmosphere from combinations of nitrogen oxides and volatile organic compounds (both emitted from vehicles) in certain meteorological conditions normally found in the summer time. It is known to reduce the lung function of some individuals, and epidemiologic studies have found evidence of increased asthma attacks and hospitalization related to increased ambient levels. It may also increase the lung’s reaction to allergens and other pollutants. Although recent studies have found associations of daily increases in ozone with increased mortality, there is not comprehensive evidence that long-term exposure causes chronic health effects, and some evidence suggests that the lung may develop a form of tolerance after repeated short-term exposures. Particulate matter (PM) in the form of PM10 and PM2.5 is material than can be inhaled that is emitted directly from motor vehicles and other sources, and that also formed in the atmosphere from atmospheric reactions with gaseous emissions (e.g., nitrogen oxides become nitrates). Although PM has been of concern for many decades, new short term and long-term epidemiologic studies published in the United States and Europe in the 1990s found associations of PM with increased mortality and morbidity at ambient levels below then-established national air quality limit values. It is these studies that have been the basis for recent action in both the European Union and the United States to establish more stringent standards for PM. These studies, some of which find the highest mortality effects for any air pollutant, also provide the basis for the estimates of population risk in Europe discussed above. In the past several years, several new epidemiologic studies have begun to strengthen the understanding of the relation between exposure to PM and mortality and morbidity. Diesel exhaust PM has been cited as a probable human carcinogen by several national and international bodies. Ultrafine particles (less than 0.1 microns), particles containing metals (e.g., iron) may be the most toxic components of the mixture. To date these studies have not identified one component or characteristic that is significantly more toxic than others. Air toxins have a variety of characteristics and effects. Most of those emitted from motor vehicles are animal carcinogens. Benzene is a known human carcinogen. Butadiene, for which vehicles are the dominant ambient source, was recently designated as a probable human carcinogen by the International Agency for Research on Cancer, and as a known human carcinogen by the U.S. National Institutes of Health. Several aldehydes (including formaldehyde and acetaldehyde) have also been designated as probable human carcinogens. In addition, several of the mobile source air toxins, especially the aldehydes, have exhibited evidence of acute respiratory effects. Recently, the U.S. Environmental Protection Agency identified a total of 21 air toxins emitted from motor vehicle exhaust. Trends and the Future. The U.S. Environmental Protection Agency took action in 1999 to further improve fuel formulation and reduce emissions of light duty vehicles, and has currently proposed stringent new fuel and emissions standards for heavy-duty vehicles. The European Union (EU) is on a similar path, which is expected to substantially reduce emissions over the coming 20 years. However, continued growth in travel is expected to offset a portion of these reductions. As a result, continued attention to reducing emissions is likely in the future.