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Personal Cars and China 7 Environment and Health One of the more obvious consequences of a rapidly growing vehicle fleet is its effect on the environment, particularly in cities. The air in most of China’s large and medium-size cities is already unacceptably polluted, with the largest cities ranked among the most polluted in the world. As seen in other countries, this situation, when exacerbated by more vehicles on the road, will not improve unless governments take firm actions to control it. This chapter examines the atmospheric pollutants generated by vehicle operation. EMISSIONS The combustion of gasoline or diesel fuel in vehicle engines produces a variety of potentially harmful emissions. The amount and type of emissions depend on a variety of factors, including engine design, operating conditions, and fuel characteristics. Evaporative hydrocarbon emissions— from refueling, spills on heated engine parts, and so forth—can be just as harmful as those from the tailpipe. Emissions from motor vehicles take two primary forms: (1) major gaseous and particulate air pollutants, which can be found in relatively high amounts in the atmosphere; and (2) air toxics, which usually are found in smaller amounts in the atmosphere but can have important effects on public health. The gaseous and particulate pollutants to which motor vehicles contribute include carbon monoxide (CO); ozone (O3), through its atmospheric precursors volatile organic compounds (VOCs) and nitrogen oxides (NOx); fine particulate matter PM10 and PM2.5, particles smaller than
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Personal Cars and China 10 and 2.5 microns (µm) in aerodynamic diameter, respectively; and nitrogen dioxide (NO2).1 The air toxics emitted by 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 pollutants emitted from motor vehicles also are produced by other sources such as industrial processes, electric power generation, and home heating. The contribution of motor vehicles to ambient levels varies, depending on the pollutant and the location. In most cases, motor vehicles are a major contributor (between 25 and 40 percent of the ambient levels), and for some pollutants—for example, carbon monoxide, ultrafine particles (PM0.1), and 1,3-butadiene—motor vehicles tend to be the dominant source. Although motor vehicles contribute a significant portion, if not the largest part, of most air pollutants, in certain circumstances they can contribute a substantially higher amount to personal exposure. In particular, in urban centers, along roadsides, and especially in urban street canyons in crowded central business districts, mobile sources can contribute 2 to 10 times as much as in general background situations.2 For example, in England urban background levels of PM10 have been measured at 22–25 micrograms per cubic meter (µg/m3), and street-side levels have been measured at 24–38 µg/m3 (Department of the Environment, Transport, and Regions, 1999). Such a finding can have important implications for the potential acute health effects arising from exposure to these pollutants and for the chronic health effects on those people who spend a significant portion of their lives in these environments, especially the elderly, low-income, and other urban populations that may be especially sensitive to the effects of air pollution. HEALTH EFFECTS Research conducted over the past several decades has identified some of the effects that different pollutants have on human health, including those on the respiratory, neurological, and cardiac systems, and those that promote several types of cancer. One of the challenges 1 Currently the ambient air quality standard is for nitrogen dioxide. Before 2000, however, there were standards for both nitrogen dioxide and nitrogen oxides, with different levels for each. A lot of the historical Chinese data are for NOx. 2 This is in general true, but for ozone, urban levels are generally lower than those found downwind of city centers, the result of the scavenging of the ambient ozone by high levels of ambient nitrogen oxides.
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Personal Cars and China of understanding these effects is that they are usually experienced as part 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 (Health Effects Institute, 2000c). 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 preexisting heart disease) may be at greater risk from exposure to air pollution than other adults. Overall, the effects of these pollutants on an individual’s health tend to be relatively small in comparison with other risk factors such as cigarette smoking. However, because a large number of people are exposed, the effects as a whole on overall public health are of sufficient magnitude to be of public concern. For example, one recent European analysis estimated that approximately 6 percent of mortality (40,000 deaths annually) in France, Austria, and Switzerland could be attributed to particulate air pollution alone, and about half of that could be attributed to exposure to vehicle emissions (Kunzli et al., 2000). The pollutants of greatest concern from vehicles are carbon monoxide, hydrocarbons (HC), nitrogen oxides, ozone (which results from the emissions of hydrocarbons and nitrogen oxides), particles, and certain toxic hydrocarbons such as benzene. Carbon Monoxide Carbon monoxide (CO)—an odorless, invisible gas created when fuels containing carbon are burned incompletely—poses a serious threat to human health. Fetuses and anyone afflicted with heart disease are especially at risk. Because hemoglobin in the blood has an affinity for carbon monoxide that is 200 times greater than that for oxygen, carbon monoxide hinders the transport of oxygen from the blood into the tissues. Therefore, more blood must be pumped to deliver the same amount of oxygen. Numerous studies in humans and animals have demonstrated that people with weak hearts are subjected to additional strain by the presence of excess carbon monoxide in the blood. In particular, clinical health studies have shown that people suffering from angina pectoris and exposed to elevated levels of ambient carbon monoxide experience angina pain more quickly than usual. Healthy people also are affected, but only at higher levels. Exposure to elevated CO levels is associated with impairment of visual perception, work capacity, manual dexterity, learning ability, and performance of complex tasks (U.S. EPA, 2000).
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Personal Cars and China Nitrogen Oxides As a class of compounds, the oxides of nitrogen (NOx) are involved in a host of environmental interactions that have adverse effects on human health and welfare and the environment. Nitrogen dioxide (NO2) has been linked with increased susceptibility to respiratory infection, increased airway resistance in asthmatics, and decreased pulmonary function (U.S. EPA, 1993a, 1995). Even short-term exposures to nitrogen dioxide have resulted in wide-ranging respiratory problems in schoolchildren—cough, runny nose, and sore throat are among the most common (Mostardi et al., 1981). Nitrogen oxides also contribute to acid deposition, which can damage trees at high elevations and, by increasing the acidity of lakes and streams, severely damage aquatic life. Finally, NOx emissions can contribute to increased levels of particulate matter by changing into nitric acid in the atmosphere and forming particulate nitrate. Photochemical Oxidants (Ozone) The science of ozone (O3) formation, transport, and accumulation is complex. Ground-level ozone is produced and destroyed in a cyclical set of chemical reactions involving nitrogen oxides, VOCs, heat, and sunlight.3 As a result, differences in NOx and VOC emissions, their ratios, and weather patterns contribute to daily, seasonal, and yearly differences in ozone concentrations and differences from city to city. Many of the chemical reactions that are part of the ozone-forming cycle are sensitive to temperature and sunlight. When ambient temperatures and sunlight levels remain high for several days and the air is relatively stagnant, ozone and its precursors can build up and produce more ozone than typically would occur on a single high-temperature day.4 Further complicating matters, ozone can be transported into an area from pollution sources hundreds of miles upwind, resulting in elevated ozone levels even in areas with low VOC or NOx emissions. VOCs are emitted from a variety of sources, including motor vehicles, chemical plants, refineries, factories, consumer and commercial products, and other industrial sources. VOCs also are emitted by natural sources 3 Carbon monoxide also participates in the production of ozone, albeit at a much slower rate than most VOC and NOx compounds. 4 There is a growing concern that climate modification resulting from the increased buildup of greenhouse gases such as carbon dioxide may increase the amount of ozone produced from a given amount of nitrogen oxides and VOCs.
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Personal Cars and China such as vegetation. Nitrogen oxides are emitted largely by motor vehicles, nonroad equipment, power plants, and other sources of combustion. Based on a large number of studies, the U.S. Environmental Protection Agency (U.S. EPA) has identified several key health effects of human exposure to present levels of ozone (U.S. EPA, 1996a, 1996c). When inhaled, ozone can cause acute respiratory problems, including asthma attacks, significant temporary decreases in lung function of 15 to over 20 percent in some healthy adults, and inflammation of lung tissue, leading to increased hospital admissions and emergency room visits. Inhaling ozone also may impair the body’s immune system defenses, making people more susceptible to respiratory illnesses. Children and outdoor workers are likely to be exposed to elevated ambient levels of ozone during exercise and therefore are at greater risk of experiencing adverse health effects. In addition to its effects on human health, ozone is known to adversely affect the environment in many ways. These effects include reduced yields for commodity crops, fruits and vegetables, and commercial forests; deleterious effects on the ecosystem and vegetation in areas such as national parks; damage to urban grass, flowers, shrubs, and trees; reduced yields for tree seedlings and noncommercial forests; increased susceptibility of plants to pests; materials damage; and decreased visibility. In addition to their contribution to ozone levels, emissions of certain hydrocarbons contain toxic air pollutants that may have a significant effect on public health. Toxic Hydrocarbons The U.S. Environmental Protection Agency recently reconfirmed that benzene is a known human carcinogen by all routes of exposure (U.S. EPA, 1998). Respiration is the major source of human exposure. Long-term respiratory exposure to high levels of ambient benzene concentrations has been shown to cause cancer of the tissues that form white blood cells. Leukemias, lymphomas, and other tumor types have been observed in experimental animals exposed to benzene by inhalation or oral administration. Exposure to benzene or its metabolites also has been linked to genetic changes in humans and animals (IARC, 1982) and increased proliferation of mouse bone marrow cells (Irons et al., 1992). The occurrence of certain chromosomal changes in persons with known exposure to benzene may serve as a marker for those at risk for contracting leukemia (Lumley et al., 1990). U.S. EPA has classified formaldehyde as a probable human carcinogen based on limited evidence of carcinogenicity in humans and sufficient evidence of carcinogenicity in animal studies using rats, mice, ham-
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Personal Cars and China sters, and monkeys (U.S. EPA, 1987). Epidemiological studies of occupationally exposed workers suggest that long-term inhalation of formaldehyde may be associated with tumors of the nasopharyngeal cavity (generally the area at the back of the mouth near the nose), nasal cavity, and sinuses. Research has demonstrated that formaldehyde produces mutagenic activity in cell cultures (U.S. EPA, 1993b). The atmospheric chemistry of acetaldehyde is similar in many respects to that of formaldehyde (Ligocki and Whitten, 1991). Like formaldehyde, it is produced and destroyed by atmospheric chemical transformation. Acetaldehyde is classified by the U.S. EPA as a probable human carcinogen. The pollutant 1,3-butadiene is formed in vehicle exhaust by the incomplete combustion of fuel. It was classified by the U.S. EPA as a Group B2 (probable human) carcinogen in 1985 (U.S. EPA, 1985). This classification was based on evidence from two species of rodents and epidemiological data. Particulates Particulate matter (PM) is a broad class of chemically and physically diverse substances that exist as discrete particles (liquid droplets or solids) over a wide range of sizes. Human-generated sources of particles include a variety that is either stationary or mobile. Particles may be emitted directly to the atmosphere or may be formed by transformations of gaseous emissions such as sulfur dioxide or nitrogen oxides. The major chemical and physical properties of particulate matter vary greatly with time, region, meteorology, and source category, thereby complicating any assessment of the health and welfare effects that might be related to various indicators of particulate pollution. At elevated concentrations, particulate matter can adversely affect human health, visibility, and materials. Components of particulate matter (e.g., sulfuric or nitric acid) contribute to acid deposition (U.S. EPA, 1996b). The key health effects associated with particulate matter include premature death; aggravation of respiratory and cardiovascular disease, as indicated by increased hospital admissions and emergency room visits, school absences, lost work days, and restricted activity days; changes in lung function and increased respiratory symptoms; changes to lung tissues and structure; and altered respiratory defense mechanisms (U.S. EPA, 1996b). Most of these effects have been consistently associated with ambient PM concentrations, used as a measure of population exposure, in a large number of community epidemiological studies. Additional information and insights on these effects are provided by studies of animal toxicology and controlled human exposures to various constituents of
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Personal Cars and China particulate matter conducted at higher-than-ambient concentrations. Although the mechanisms by which particles produce effects are not well known, there is general agreement that the cardiorespiratory system is the major target of the effects of particulate matter. People with infectious respiratory disease (e.g., pneumonia) are at greater risk of premature mortality and morbidity (e.g., hospitalization, aggravation of respiratory symptoms) from exposure to ambient particulate matter. Also, such exposure may increase a healthy person’s susceptibility to respiratory infections. The elderly, children, and the asthmatic face even greater risks. Fine and coarse fraction particles have fundamental physical and chemical differences. The fine fraction contains acid aerosols, sulfates, nitrates, transition metals, diesel exhaust particles, and ultrafine particles, and the coarse fraction typically contains high mineral concentrations, silica, and suspended dust. Exposure to coarse fraction particles is primarily associated with the aggravation of respiratory conditions such as asthma. Fine particles are most closely associated with health effects such as cardiopulmonary diseases. The strongest evidence for ambient PM exposure health risks is derived from epidemiological studies (Health Effects Institute, 2000a, 2000b). Many have shown statistically significant associations of ambient PM levels with a variety of human health endpoints in sensitive populations, including mortality, hospital admissions and emergency room visits, respiratory illness and symptoms, and physiological changes in mechanical pulmonary function. The epidemiological science points to fine particulate matter being more strongly associated with acute conditions and premature mortality than coarse fraction particulate matter, which is associated with chronic health effects. Time-series analyses strongly suggest a positive effect on daily mortality across the entire range of ambient PM levels. Relative risk estimates for daily mortality in relation to daily ambient PM concentration are consistently positive and statistically significant (at PM0.05), across a variety of statistical modeling approaches and methods of adjustment for effects of relevant covariates such as season, weather, and copollutants. Diesel Emissions Diesel emissions deserve a special discussion because they tend to be a dominant source of mobile source cancer risk. In 1993 the U.S. Environmental Protection Agency determined a reference concentration to minimize the noncancer health effects of exposure to diesel exhaust. Based on information provided in the draft “Health Assessment Document for Diesel Emissions” and other sources of information, the U.S. EPA concluded
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Personal Cars and China that diesel particulate is a probable human carcinogen. The most compelling information to suggest a carcinogenic hazard is the consistent association observed between increased lung cancer and diesel exhaust exposure in certain workers laboring in the presence of diesel engines (Health Effects Institute, 1999). Approximately 30 individual epidemiological studies have shown increased lung cancer risks of 20–89 percent within the study populations. The analytical results of pooling the positive study results reveal that on average the lung cancer risks were increased by 33– 47 percent. The magnitude of the pooled risk increase is not precise because of the uncertainties in the individual studies, the most important of which is a continuing concern about whether smoking effects were accounted for adequately. Although not all studies demonstrated an increased risk—6 of 34 epidemiological studies summarized by the Health Effects Institute (1995) reported relative risks of less than 1.0—the fact that an increased risk has been consistently noted in the majority of epidemiological studies strongly supports the determination that exposure to diesel exhaust is likely to pose a carcinogenic hazard to humans. Additional evidence that supports treating diesel exhaust as a carcinogen at ambient levels of exposure is provided by the observation of small quantities of many mutagenic and some carcinogenic compounds in the diesel exhaust. A carcinogenic response to such agents is assumed not to have a threshold unless there is direct evidence to the contrary. In addition, there is evidence that at least some of the organic compounds associated with diesel particulate matter are extracted by lung fluids (i.e., are bioavailable) and therefore are dispensed in some quantity to the lungs and able to enter the bloodstream and travel to other sites in the body. Several national and international agencies have designated diesel exhaust or diesel particulate matter as a ”potential” (National Institute for Occupational Safety and Health) or ”probable” (International Agency for Research on Cancer) human carcinogen (NIOSH, 1988, IARC, 1989). Based on the IARC findings, in 1990 the state of California identified diesel exhaust as a chemical known to the state to cause cancer, and after an extensive review in 1998 it listed diesel exhaust as a toxic air contaminant (California Environmental Protection Agency, 1998). The World Health Organization recommends that “urgent efforts should be made to reduce [diesel engine] emissions, specifically of particulates, by changing exhaust train techniques, engine design and fuel composition” (WHO, 1996). More recently, in its Ninth National Toxicology Program Report on Carcinogens the National Institute for Environmental Health Sciences added diesel particulate to its list of substances that are reasonably thought to be human carcinogens (NIEHS, 2001). Another aspect of diesel particulate that is a cause for concern is its size. Approximately 80–95 percent of diesel particle mass is in the size range of
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Personal Cars and China 0.05–1.0 µm with a mean particle diameter of about 0.2 µm. These fine particles have a very large surface area per gram of mass, which make them excellent carriers for adsorbed inorganic and organic compounds that can effectively reach the lowest airways of the lung. Some 50–90 percent of the numbers of particles in diesel exhaust are in the ultrafine size range, from 0.005 to 0.05 µm, averaging about 0.02 µm. Ultrafine diesel particulate matter, which accounts for the majority of the number of particles, also accounts for 1–20 percent of the mass of diesel particulate matter. CLIMATE CHANGE Beyond direct adverse health effects, vehicle emissions are a source of other concerns. Among these is climate change, or the greenhouse effect. Greenhouse warming occurs when certain gases allow sunlight to penetrate to the Earth but partially trap the planet’s radiated infrared heat in the atmosphere. Some such warming is natural and necessary. If there were no water vapor, carbon dioxide, methane, and other infrared absorbing (greenhouse) gases in the atmosphere trapping the Earth’s radiant heat, the planet would be about 60 degrees Fahrenheit (or 33 degrees Celsius) colder, and life as we know it would not be possible. Naturally occurring greenhouse gases include water vapor, carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and ozone (O3). Several classes of halogenated substances that contain fluorine, chlorine, or bromine are also greenhouse gases, but they are, for the most part, solely a product of industrial activities. Chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) are halocarbons that contain chlorine, and halocarbons that contain bromine are known as halons. Other fluorine-containing halogenated substances include hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulfur hexafluoride (SF6). Although they do not have a direct global warming effect, several gases do influence the formation and destruction of ozone, which has a terrestrial radiation-absorbing effect. These gases include carbon monoxide, oxides of nitrogen, and nonmethane volatile organic compounds (NMVOCs). Aerosols, extremely small particles or liquid droplets often produced by emissions of sulfur dioxide (SO2), also can affect the absorptive characteristics of the atmosphere. Although carbon dioxide, methane, and nitrous oxide occur naturally in the atmosphere, the atmospheric concentration of each has risen, largely as a result of human activities. Since 1800, atmospheric concentrations of these greenhouse gases have increased by 30, 145, and 15 percent, respectively (IPCC, 1996). This buildup has altered the composition of the Earth’s atmosphere and may affect the global climate system.
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Personal Cars and China Beginning in the 1950s, the use of CFCs and other ozone-depleting substances (ODSs) increased by nearly 10 percent a year, until the mid-1980s when international concern about ozone depletion led to the signing of the Montreal Protocol. Since then, the use of ODSs has declined rapidly, and they are being phased out completely. In contrast, the use of ODS substitutes, such as hydrofluorocarbons, perfluorocarbons, and sulfur hexafluoride, has grown significantly, and all have strong greenhouse forcing effects. In late November 1995 Working Group 1 of the International Panel on Climate Change (IPCC) concluded that “the balance of evidence suggests that there is a discernible human influence on global climate” (IPCC, 1996).5 In December 1997, acting on this consensus, countries around the world approved the Kyoto Protocol to the 1992 Climate Change Treaty. When, and if, the protocol is ratified by 55 nations, representing 55 percent of 1990 CO2 emissions, 38 industrialized nations will be required to reduce, by between 2008 and 2012, their greenhouse gas emissions from the 1990 levels. The European Union would reduce emissions by 8 percent, the United States by 7 percent, and Japan by 6 percent.6 Some nations would face smaller reductions, and a few would not face any for the moment. As a group, the industrialized nations would cut back on the emissions of such gases by just more than 5 percent. Emissions of six gases would be affected: carbon dioxide, methane, nitrous oxide, and three halocarbons used as substitutes for ozone-damaging chlorofluorocarbons. The greenhouse gases most closely identified with the transportation sector include carbon dioxide, nitrous oxide, and methane (see Table 7-1 for the global warming potential of nitrous oxide and methane relative to carbon dioxide). Other vehicle-related pollutants also contribute to global warming, but their quantification has been more difficult. These include carbon monoxide, nonmethane hydrocarbons (NMHC), and nitrogen dioxide. In the original (1990) IPCC report, global warming potentials (GWPs) were attributed to these gases (Shine et al., 1990). Because of difficulty reaching agreement on the appropriate quantification, specific GWPs for these gases were not contained in the most recent IPCC report (Table 7-1). In most countries, over 90 percent of the global warming potential of the direct-acting greenhouse gases from the transportation sector comes from carbon dioxide, and therefore the global warming potential from 5 In its most recent draft report, the IPCC has removed the qualifier to say, “There is a discernible human influence on global climate.” 6 The U.S. government recently indicated that it will not ratify the Kyoto Protocol but that it intends to suggest an alternative approach.
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Personal Cars and China TABLE 7-1 IPCC’s Global Warming Potential (GWP) for Carbon Monoxide, Methane, Nonmethane Hydrocarbons, Nitrogen Dioxide, and Nitrous Oxide GWP Carbon Monoxide (CO) Methane (CH4) Nonmethane Hydrocarbons (NMHC) Nitrogen Dioxide (NO2) Nitrous Oxide (N2O) 20-year horizon 7 56 31 30 280 100-year horizon 3 21 11 07 310 500-year horizon 2 6.5 06 02 170 NOTE: The time horizon is the time period over which the GWP is measured relative to carbon dioxide. Different gases have different lifetimes in the atmosphere. SOURCE: IPCC (1996). transportation is most closely related to fuel economy. The transportation sector is responsible for about 17 percent of global CO2 emissions, and these emissions are increasing in virtually every part of the world. Even the potential global warming benefits of diesel vehicles, because they are more fuel-efficient than gasoline-fueled vehicles, have been undercut by recent studies, which indicate that diesel particles may, by reducing cloud cover and rainfall, more than offset any CO2 advantage they offer. As James Hansen and his colleagues at the U.S. National Aeronautics and Space Administration (NASA) have noted, “Black carbon7 reduces aerosol albedo, causes a semi-direct reduction of cloud cover, and reduces cloud particle albedo” (Hansen et al., 2001). Tight control of diesel particulate emissions would reduce their negative greenhouse effect and allow full greenhouse benefits from the CO2 advantage that diesels provide. AIR QUALITY One result of the rapid growth of China’s vehicle fleet has been a significant increase in urban air pollution. In spite of significant advances in industrial pollution control, air pollution in the major Chinese cities remains a serious problem and in some cases may actually be worsening. It is generally characterized as a shift from coal-based pollution to vehicle-based pollution. Based on the available data, it is clear that the national NOx air quality standards are currently exceeded across large areas in China, including but not limited to high traffic ones. Before 1992, the annual average NOx 7 Black carbon pollution is the release of particulates from burning fuel into the air.
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Personal Cars and China TABLE 7-2 Ozone Concentration in Beijing, 1997–1999 Number of Nonattainment Days Number of Nonattainment Hours Maximum Hourly Concentration (µg/m3) 1997 71 434 346 1998 101 504 384 1999 119 777 — NOTE: “Nonattainment” hours means time that the respective air quality standard was exceeded in Beijing, which occurred on the indicated number of distinct nonattainment days. The maximum hourly concentration was the highest value observed. — = not available; (µg/m3) = micrograms per cubic meter. SOURCE: He Kebin, Tsinghua University, Beijing. concentration in Shanghai was lower than 50 micrograms per cubic meter (µg/m3), which complied with the Chinese Class II air quality standard. But since 1995 the NOx concentration has been gradually increasing, from 51 µg/m3 in 1995 to 59 µg/m3 in 1997 (Shanghai Municipal Government, 1999). In Beijing, NOx concentrations within the Second Ring Road that encircles the city center increased from 99 µg/m3 in 1986 to 205 µg/m3 in 1997, more than doubling in a decade. Moreover, CO and NOx concentrations on the urban trunk traffic roads and interchanges exceed national environmental quality standards year-round (Beijing Municipal Environmental Protection Bureau et al., 1999). National air quality standards for particulates also are frequently exceeded—primarily because of coal and charcoal burning. Recent data indicate as well that standards for ozone, formed by the photochemical reaction of nitrogen oxides and hydrocarbons, have been exceeded in several metropolitan areas during the last decade (see Table 7-2, which shows a clear upward trend in Beijing). On average, mobile sources are currently contributing 45–60 percent of NOx emissions and about 85 percent of CO emissions in typical Chinese cities (Project of China Environment Technological Assistance Loaned by the World Bank B-9-3, 1997). For example, data collected in Shanghai show that in 1996, of the total air pollution load in the downtown area, vehicles emitted 86 percent of the carbon monoxide, 56 percent of the nitrogen oxides, and 96 percent of the nonmethane hydrocarbons (Shanghai Municipal Government, 1999). In Beijing in recent years, the NOx concentration shows a clear upward trend. In 1997 the annual average NOx concentration was 133 µg/m3, the average concentration during the heating season was 191 µg/m3, and that during the non-heating season was 99 µg/m3. These emissions were, respectively, 73 percent, 66 per-
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Personal Cars and China cent, and 80 percent higher than those 10 years ago. The annual daily average NOx concentration in 1998 was 14.3 percent higher than in 1997. Because the amount of coal burning has remained stable for many years, Beijing local authorities attribute the increases to vehicular emissions (Beijing Municipal Environmental Protection Bureau et al., 1999). According to the Beijing Municipal Environmental Protection Bureau, “In 2000, NOx emissions by motor vehicles accounted for 43% of the total and CO emissions, 83%. As the vehicle discharges pollutants at low altitude, it contributes to 73% and 84% of the effect on environmental quality.”8 In response to the air pollution problem, China has initiated a motor vehicle pollution control effort. It has moved quickly to eliminate the use of leaded gasoline and recently introduced European Emission Standard I (Euro I) for new cars and trucks. It will introduce the Euro II standards in 2004.9 Nevertheless, the emissions requirements for new vehicles lag behind those of the industrialized world by about a decade. Furthermore, without additional improvements in fuel quality, greater tightening of new vehicle standards will be difficult (see Chapter 5). Another factor is that in China road conditions and maintenance practices are exacerbating the air pollution problem. The Chinese government has expended a great effort to mitigate the primary pollutants such as SO2, NOx, and PM10 in many cities—the levels of these pollutants are measured routinely by the central and local governments. However, secondary pollutants such as photochemical smog (ozone) and the fine particles emitted by primary and secondary sources are far greater threats to human health. Vehicular emissions contribute significantly to the formation of ground-level ozone and fine particles, as well as to an increase in greenhouse gases. IMPLICATIONS OF CHINA’S VEHICLE GROWTH FOR FUTURE EMISSIONS AND FUEL CONSUMPTION As indicated in Chapter 2, China is anticipating a threefold to sevenfold increase in its vehicle fleet, not including motorcycles, between 2002 and 2020 (see Table 2-1). The number of cars, in particular, is expected to increase by three to nine times in the same time period. This section summarizes emissions and fuel consumption estimates that are based on the vehicle characteristics in the five-year plan for the automotive industry. Using the medium-growth scenario from Chapter 2, Figure 7-1 indicates 8 Yu Xiaoxuan, Beijing Municipal Environmental Protection Bureau. 9 Beijing will introduce Euro II standards one year earlier than the rest of the country in 2003.
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Personal Cars and China FIGURE 7-1 Motor vehicle emissions in China, 2000–2020. NOTE: THC = total hydrocarbons; CO = carbon monoxide; NOx = nitrogen oxides; PM = particulate matter; CH4 = methane; CO2 = carbon dioxide. SOURCE: Calculations by Michael P. Walsh. that motor vehicle emissions of carbon dioxide will about quadruple between 2000 and 2020; CO and hydrocarbon levels will about triple; and NOx and PM levels will stay essentially at the currently high levels. For light-duty vehicles (and the medium-growth scenario), the pollution trends are somewhat better (see Table 7-3). However, CO and NOx levels will increase, and CO2 emissions are estimated to be more than three and a half times higher in 2020 than in 2000. If the highest-growth scenario should become reality, motor vehicle emissions of all pollutants would increase and carbon dioxide would skyrocket (Figure 7-2). The potential for reducing fuel consumption and CO2 emissions was investigated using two cases that focused on light-duty vehicles. In case 1, it was assumed that starting in 2005 the fuel economy of all new gasoline-fueled cars and light trucks improved by 2 percent a year. Case 2 further assumed that starting in model year 2010, 5 percent of highly efficient cars and light trucks (and increasing by 5 percent a year) achieve fuel consumption of 80 miles per gallon (mpg). As illustrated in Figure 7-3, under these scenarios the growth in fuel consumption falls but several more years will be needed for the full effects to be felt. For case 2, by 2020 from 12 billion to over 30 billion gallons of fuel will be saved compared with the base case, depending on which vehicle growth rate occurs.
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Personal Cars and China TABLE 7-3 Light-duty Vehicle Emissions Trends in China, 2000–2020 2000 2005 2010 2015 2020 THC 1.00 1.01 0.95 0.83 0.85 CO 1.00 1.13 1.22 1.29 1.56 NOx 1.00 1.19 1.31 1.30 1.42 PM 1.00 1.01 1.04 0.94 0.96 CO2 1.00 1.41 1.97 2.77 3.87 NOTE: Values shown are emissions normalized to base year 2000. THC = total hydrocarbons; CO = carbon monoxide; NOx = nitrogen oxides; PM = particulate matter; CO2 = carbon dioxide. SOURCE: Calculations by Michael P. Walsh using mid-range scenario of Chapter 2, assuming 8 percent growth of GDP. FIGURE 7-2 Motor vehicle emissions in China—European standards in 2010, light-duty fuel economy improvements starting in 2005. NOTE: THC = total hydrocarbons; CO = carbon monoxide; NOx = nitrogen oxides; PM = particulate matter; CO2 = carbon dioxide. SOURCE: Calculations by Michael P. Walsh.
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Personal Cars and China FIGURE 7-3 Light-duty carbon dioxide emissions, alternative scenarios. Base case: year 2000 trends continue; case 1: fuel economy of fleet improves at rate of 2 percent per year; case 2: same as case 1, but with the addition to the fleet of cars capable of 80 miles per gallon at a rate of 5 percent of new cars per year. SOURCE: Calculations by Michael P. Walsh In conclusion, the various pollutants emitted by vehicles are a large and potentially growing source of air pollution in China. They already account for a substantial fraction of emissions contributing to excessively high ambient levels of air pollution. Investigators have shown that these pollutants have a measurable negative effect on the public health. Even with the currently adopted emissions standards, Euro II by 2004, and a 10 percent improvement in vehicle fuel economy, as called for in the five-year plan, emissions of all pollutants will increase if high growth occurs. Even if growth is constrained to the medium case, all pollutants but particulate matter are expected to increase, although if the light-duty diesel fleet grows significantly, particulates and nitrogen oxides will increase more and CO2 emissions will be lower. As a result, efforts to reduce vehicle emissions must continue, to avoid the concomitant impacts on public health and the environment. If growth can be constrained to the medium case and if emissions standards are aligned with those of the European Union by 2010, it
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Personal Cars and China should be possible to actually reduce vehicle emissions of total hydrocarbons, carbon monoxide, nitrogen oxides, and particulate matter. A complementary vehicle fuel efficiency program will be needed to slow down the growth in CO2 emissions and fuel consumption. According to a recent study by Shao et al. (2001), the only way for Guangzhou City to achieve its air quality targets by 2010 is to advance the implementation of Euro III standards to as early as 2004. Acceleration of the implementation schedule was found to be technically feasible, because the vehicle technologies needed to meet Euro III are already available. Such a step also would advance China’s prospects of meeting Euro IV standards by 2010. However, considerations of fuel quality, infrastructure, and economic cost must be addressed. In view of the very rapid growth in the vehicle fleet forecast for the next two decades, China’s environment could face severe strains and significant public health consequences unless vehicle technology is substantially upgraded and fuel quality improved. Similarly, fuel consumption and greenhouse gas emissions will increase dramatically without substantial improvements in vehicle technology. China should strongly consider developing the appropriate mix of performance standards and incentives necessary to leapfrog from today’s modest requirements to the global state of the art as rapidly as possible. REFERENCES Beijing Municipal Environmental Protection Bureau, Beijing Municipal Public Security and Traffic Administration Bureau, and Beijing Urban Planning, Design and Research Academy. 1999. Urban Transport and Environment in Beijing. January 15. California Environmental Protection Agency. 1998. Proposed Identification of Diesel Exhaust as a Toxic Air Contaminant. Appendix III, Part A: Exposure Assessment. California Environmental Protection Agency, California Air Resources Board, April 22. Department of the Environment, Transport, and Regions. 1999. Source Apportionment of Airborne Particulate Matter in the United Kingdom. Report of the Airborne Particles Expert Group. London, January. Hansen, J., M. Sato, R. Ruedy, A. Lacis, and V. Oinas. 2001. Global Warming in the 21st Century: An Alternative Scenario. Online. NASA Goddard Institute for Space Studies. Available at www.giss.nasa.gov/research/impacts/altscenario/. Accessed August 30, 2002. Health Effects Institute. 1995. Diesel Exhaust: A Critical Analysis of Emissions, Exposure, and Health Effects . Cambridge, Mass., April. ———. 1999. Diesel Emissions and Lung Cancer: Epidemiology and Quantitative Risk Assessment. A Special Report of the Institute’s Diesel Epidemiology Expert Panel. Cambridge, Mass., June. ———. 2000a. The National Morbidity, Mortality, and Air Pollution Study. Research Report 94, Part II. Cambridge, Mass. ———. 2000b. Reanalysis of the Harvard Six Cities and American Cancer Society Studies. A Special Report of the Institute’s Particle Epidemiology Reanalysis Project. Cambridge, Mass.
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