Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.
7 Environment and Health O ne of the more obvious consequences of a rapidly growing ve- hicle fleet is its effect on the environment, particularly in cities. The air in most of Chinaâs large and medium-size cities is already unacceptably polluted, with the largest cities ranked among the most pol- luted in the world. As seen in other countries, this situation, when exacer- bated by more vehicles on the road, will not improve unless governments take firm actions to control it. This chapter examines the atmospheric pol- lutants 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 emis- sions depend on a variety of factors, including engine design, operating conditions, and fuel characteristics. Evaporative hydrocarbon emissionsâ from refueling, spills on heated engine parts, and so forthâcan be just as harmful as those from the tailpipe. Emissions from motor vehicles take two primary forms: (1) major gas- eous 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 pub- lic health. The gaseous and particulate pollutants to which motor vehicles contribute include carbon monoxide (CO); ozone (O3), through its atmo- spheric precursors volatile organic compounds (VOCs) and nitrogen ox- ides (NOx); fine particulate matter PM10 and PM2.5, particles smaller than 150
ENVIRONMENT AND HEALTH 151 10 and 2.5 microns (Âµm) in aerodynamic diameter, respectively; and ni- trogen dioxide (NO2).1 The air toxics emitted by motor vehicles include aldehydes (acetaldehyde, formaldehyde, and others), benzene, 1,3-buta- diene, 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 ambi- ent levels), and for some pollutantsâfor example, carbon monoxide, ultrafine particles (PM0.1), and 1,3-butadieneâmotor 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 con- tribute 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 22â25 micrograms per cubic meter (Âµg/m3), and street-side levels have been measured at 24â38 Âµg/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, in- cluding 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.
152 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 dis- entangle 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 individualâs health tend to be relatively small in comparison with other risk factors such as ciga- rette 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 esti- mated 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 monox- ide, 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)âan odorless, invisible gas created when fu- els containing carbon are burned incompletelyâposes a serious threat to human health. Fetuses and anyone afflicted with heart disease are espe- cially 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. Nu- merous 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).
ENVIRONMENT AND HEALTH 153 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 air- way 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 schoolchildrenâcough, 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 in- creased levels of particulate matter by changing into nitric acid in the at- mosphere 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 sun- light.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 lev- els 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 ar- eas 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.
154 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 Protec- tion Agency (U.S. EPA) has identified several key health effects of human exposure to present levels of ozone (U.S. EPA, 1996a, 1996c). When in- haled, ozone can cause acute respiratory problems, including asthma at- tacks, 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 bodyâs 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 dur- ing 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; del- eterious 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 ef- fect 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 concentra- tions 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 admin- istration. Exposure to benzene or its metabolites also has been linked to genetic changes in humans and animals (IARC, 1982) and increased pro- liferation of mouse bone marrow cells (Irons et al., 1992). The occurrence of certain chromosomal changes in persons with known exposure to ben- zene 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 carcino- gen based on limited evidence of carcinogenicity in humans and suffi- cient evidence of carcinogenicity in animal studies using rats, mice, ham-
ENVIRONMENT AND HEALTH 155 sters, and monkeys (U.S. EPA, 1987). Epidemiological studies of occupa- tionally exposed workers suggest that long-term inhalation of formalde- hyde may be associated with tumors of the nasopharyngeal cavity (gener- ally the area at the back of the mouth near the nose), nasal cavity, and sinuses. Research has demonstrated that formaldehyde produces mu- tagenic activity in cell cultures (U.S. EPA, 1993b). The atmospheric chemistry of acetaldehyde is similar in many re- spects to that of formaldehyde (Ligocki and Whitten, 1991). Like formal- dehyde, it is produced and destroyed by atmospheric chemical transfor- mation. 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 in- complete 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 classifica- tion was based on evidence from two species of rodents and epidemio- logical data. Particulates Particulate matter (PM) is a broad class of chemically and physically diverse substances that exist as discrete particles (liquid droplets or sol- ids) over a wide range of sizes. Human-generated sources of particles in- clude a variety that is either stationary or mobile. Particles may be emit- ted 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 vari- ous indicators of particulate pollution. At elevated concentrations, par- ticulate matter can adversely affect human health, visibility, and materi- als. 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 pre- mature 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 tis- sues 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 infor- mation and insights on these effects are provided by studies of animal toxicology and controlled human exposures to various constituents of
156 PERSONAL CARS AND CHINA particulate matter conducted at higher-than-ambient concentrations. Al- though 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 particu- late matter. Also, such exposure may increase a healthy personâs suscepti- bility 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, ni- trates, 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 prima- rily 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 de- rived from epidemiological studies (Health Effects Institute, 2000a, 2000b). Many have shown statistically significant associations of ambient PM lev- els with a variety of human health endpoints in sensitive populations, including mortality, hospital admissions and emergency room visits, res- piratory illness and symptoms, and physiological changes in mechanical pulmonary function. The epidemiological science points to fine particu- late matter being more strongly associated with acute conditions and pre- mature mortality than coarse fraction particulate matter, which is associ- ated with chronic health effects. Time-series analyses strongly suggest a positive effect on daily mor- tality across the entire range of ambient PM levels. Relative risk estimates for daily mortality in relation to daily ambient PM concentration are con- sistently 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. Environ- mental Protection Agency determined a reference concentration to mini- mize the noncancer health effects of exposure to diesel exhaust. Based on information provided in the draft âHealth Assessment Document for Die- sel Emissionsâ and other sources of information, the U.S. EPA concluded
ENVIRONMENT AND HEALTH 157 that diesel particulate is a probable human carcinogen. The most compel- ling information to suggest a carcinogenic hazard is the consistent asso- ciation observed between increased lung cancer and diesel exhaust expo- sure 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 20â89 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 33â 47 percent. The magnitude of the pooled risk increase is not precise be- cause of the uncertainties in the individual studies, the most important of which is a continuing concern about whether smoking effects were ac- counted for adequately. Although not all studies demonstrated an in- creased riskâ6 of 34 epidemiological studies summarized by the Health Effects Institute (1995) reported relative risks of less than 1.0âthe fact that an increased risk has been consistently noted in the majority of epide- miological 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 car- cinogen 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 âpotentialâ (National Institute for Occupational Safety and Health) or âprobableâ (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 ex- haust as a chemical known to the state to cause cancer, and after an exten- sive review in 1998 it listed diesel exhaust as a toxic air contaminant (Cali- fornia Environmental Protection Agency, 1998). The World Health Organization recommends that âurgent efforts should be made to reduce [diesel engine] emissions, specifically of particulates, by changing exhaust train techniques, engine design and fuel compositionâ (WHO, 1996). More recently, in its Ninth National Toxicology Program Report on Carcinogens the National Institute for Environmental Health Sciences added diesel par- ticulate 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 80â95 percent of diesel particle mass is in the size range of
158 PERSONAL CARS AND CHINA 0.05â1.0 Âµm with a mean particle diameter of about 0.2 Âµm. These fine par- ticles 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 50â90 percent of the numbers of particles in diesel exhaust are in the ultrafine size range, from 0.005 to 0.05 Âµm, averaging about 0.02 Âµm. Ultrafine diesel particulate mat- ter, which accounts for the majority of the number of particles, also accounts for 1â20 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 pen- etrate to the Earth but partially trap the planetâs 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 ab- sorbing (greenhouse) gases in the atmosphere trapping the Earthâs radi- ant 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, chlo- rine, 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 fluo- rine-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 monox- ide, 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 charac- teristics 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, respec- tively (IPCC, 1996). This buildup has altered the composition of the Earthâs atmosphere and may affect the global climate system.
ENVIRONMENT AND HEALTH 159 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 sign- ing 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 sul- fur 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 âthe balance of evidence suggests that there is a discernible human influence on global climateâ (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 per- cent 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 per- cent, the United States by 7 percent, and Japan by 6 percent.6 Some na- tions 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 ha- locarbons 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 di- oxide. In the original (1990) IPCC report, global warming potentials (GWPs) were attributed to these gases (Shine et al., 1990). Because of diffi- culty 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, âThere is a discernible human influence on global climate.â 6 The U.S. government recently indicated that it will not ratify the Kyoto Protocol but that it intends to suggest an alternative approach.
160 PERSONAL CARS AND CHINA TABLE 7-1 IPCCâs Global Warming Potential (GWP) for Carbon Monoxide, Methane, Nonmethane Hydrocarbons, Nitrogen Dioxide, and Nitrous Oxide Carbon Nonmethane Nitrogen Nitrous Monoxide Methane Hydrocarbons Dioxide Oxide GWP (CO) (CH4) (NMHC) (NO2) (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 under- cut 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, âBlack carbon7 reduces aerosol albedo, causes a semi-direct reduction of cloud cover, and reduces cloud particle albedoâ (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 Chinaâs 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 ve- hicle-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.
ENVIRONMENT AND HEALTH 161 TABLE 7-2 Ozone Concentration in Beijing, 1997â1999 Number of Number of Maximum Hourly Nonattainment Days Nonattainment Hours Concentration (Âµg/m3) 1997 71 434 346 1998 101 504 384 1999 119 777 â NOTE: âNonattainmentâ hours means time that the respective air quality standard was ex- ceeded in Beijing, which occurred on the indicated number of distinct nonattainment days. The maximum hourly concentration was the highest value observed. â = not available; (Âµg/m3) = micrograms per cubic meter. SOURCE: He Kebin, Tsinghua University, Beijing. concentration in Shanghai was lower than 50 micrograms per cubic meter (Âµg/m3), which complied with the Chinese Class II air quality standard. But since 1995 the NOx concentration has been gradually increasing, from 51 Âµg/m3 in 1995 to 59 Âµg/m3 in 1997 (Shanghai Municipal Government, 1999). In Beijing, NOx concentrations within the Second Ring Road that en- circles the city center increased from 99 Âµg/m3 in 1986 to 205 Âµg/m3 in 1997, more than doubling in a decade. Moreover, CO and NOx concentra- tions on the urban trunk traffic roads and interchanges exceed national environmental quality standards year-round (Beijing Municipal Environ- mental Protection Bureau et al., 1999). National air quality standards for particulates also are frequently exceededâprimarily 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 45â60 percent of NOx emissions and about 85 percent of CO emissions in typical Chi- nese 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 down- town 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 aver- age NOx concentration was 133 Âµg/m3, the average concentration during the heating season was 191 Âµg/m3, and that during the non-heating sea- son was 99 Âµg/m3. These emissions were, respectively, 73 percent, 66 per-
162 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). Accord- ing to the Beijing Municipal Environmental Protection Bureau, âIn 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.â8 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 be- hind 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 citiesâthe levels of these pollutants are measured routinely by the central and local gov- ernments. 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 CHINAâS VEHICLE GROWTH FOR FUTURE EMISSIONS AND FUEL CONSUMPTION As indicated in Chapter 2, China is anticipating a threefold to seven- fold 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 sum- marizes 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 8Yu Xiaoxuan, Beijing Municipal Environmental Protection Bureau. 9Beijing will introduce Euro II standards one year earlier than the rest of the country in 2003.
ENVIRONMENT AND HEALTH 163 5.00 4.50 4.00 Normalized to 2000 3.50 3.00 2.50 2.00 1.50 1.00 0.50 0.00 2000 2005 2010 2015 2020 Year THC CO NOx PM CH4 CO2 FIGURE 7-1 Motor vehicle emissions in China, 2000â2020. 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 be- tween 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 pollu- tion 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 sce- nario 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 con- sumption 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.
164 PERSONAL CARS AND CHINA TABLE 7-3 Light-duty Vehicle Emissions Trends in China, 2000â2020 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 = particu- late matter; CO2 = carbon dioxide. SOURCE: Calculations by Michael P. Walsh using mid-range scenario of Chap- ter 2, assuming 8 percent growth of GDP. 6.00 5.00 Normalized to 2000 4.00 3.00 2.00 1.00 0.00 2000 2005 2010 2015 2020 Year THC CO NOx PM CO2 FIGURE 7-2 Motor vehicle emissions in ChinaâEuropean standards in 2010, light-duty fuel economy improvements starting in 2005. NOTE: THC = total hy- drocarbons; CO = carbon monoxide; NOx = nitrogen oxides; PM = particulate matter; CO2 = carbon dioxide. SOURCE: Calculations by Michael P. Walsh.
ENVIRONMENT AND HEALTH 165 4.50 4.00 3.50 Normalized to 2000 3.00 2.50 2.00 1.50 1.00 0.50 0.00 2000 2005 2010 2015 2020 Year Base case Case 1 Case 2 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 ac- count for a substantial fraction of emissions contributing to excessively high ambient levels of air pollution. Investigators have shown that these pollut- ants 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 emis- sions standards are aligned with those of the European Union by 2010, it
166 PERSONAL CARS AND CHINA should be possible to actually reduce vehicle emissions of total hydrocar- bons, carbon monoxide, nitrogen oxides, and particulate matter. A comple- mentary 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 Chinaâs prospects of meeting Euro IV standards by 2010. However, considerations of fuel quality, infrastruc- ture, and economic cost must be addressed. In view of the very rapid growth in the vehicle fleet forecast for the next two decades, Chinaâs environment could face severe strains and sig- nificant public health consequences unless vehicle technology is substan- tially upgraded and fuel quality improved. Similarly, fuel consumption and greenhouse gas emissions will increase dramatically without substan- tial improvements in vehicle technology. China should strongly consider developing the appropriate mix of performance standards and incentives necessary to leapfrog from todayâs 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 Acad- emy. 1999. Urban Transport and Environment in Beijing. January 15. California Environmental Protection Agency. 1998. Proposed Identification of Diesel Ex- haust as a Toxic Air Contaminant. Appendix III, Part A: Exposure Assessment. Califor- nia 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. âââ. 1999. Diesel Emissions and Lung Cancer: Epidemiology and Quantitative Risk As- sessment. A Special Report of the Instituteâs Diesel Epidemiology Expert Panel. Cam- bridge, Mass., June. âââ. 2000a. The National Morbidity, Mortality, and Air Pollution Study. Research Report 94, Part II. Cambridge, Mass. âââ. 2000b. Reanalysis of the Harvard Six Cities and American Cancer Society Studies. A Special Report of the Instituteâs Particle Epidemiology Reanalysis Project. Cambridge, Mass.
ENVIRONMENT AND HEALTH 167 âââ. 2000c. Strategic Plan for the Health Effects of Air Pollution, 2000â2005. Cambridge, Mass. International Agency for Research on Cancer (IARC). 1982. Some Industrial Chemicals and Dyestuffs. Vol. 29, IARC Monographs on the Evaluation of Carcinogenic Risk of Chemi- cals to Humans. IARC, World Health Organization, Lyon, France. âââ. 1989. Diesel and Gasoline Engine Exhausts and Some Nitroarenes. Vol. 46, Mono- graphs on the Evaluation of Carcinogenic Risks to Humans. IARC, World Heath Orga- nization, Lyon, France. International Panel on Climate Change (IPCC). 1996. Climate Change 1995: The Science of Climate Change, J. T. Houghton et al., eds. New York: Cambridge University Press. Irons, R. D., W. S. Stillman, D. B. Colagiovanni, and V. A. Henry. 1992. Synergistic action of the benzene metabolite hydroquinone on myelopoietic stimulating activity of granulo- cyte/macrophage colony-stimulating factor in vitro. Proceedings of the National Acad- emy of Sciences 89:3691â3695. Kunzli, N., R. Kaiser, S. Medina, M. Studnicka, O. Chanel, P. Filliger, M. Herry, F. Horak Jr., V. Puybonnieux-Texier, P. QuÃ©nel, J. Schneider, R. Seethaler, J-C. Vergnaud, and H. Sommer. 2000. Public-health impact of outdoor and traffic-related air pollution: A Eu- ropean assessment. Lancet 356 (September 2). Ligocki, M. P., and G. Z. Whitten. 1991. Atmospheric Transformation of Air Toxics: Acetal- dehyde and Polycyclic Organic Matter. SYSAPP-91/113. Systems Applications Inter- national, San Rafael, Calif. Lumley, M., H. Barker, and J. A. Murray. 1990. Benzene in petrol. Lancet 336:1318â1319. Mostardi, R. A., et al. 1981. The University of Akron study on air pollution and human health effects. Archives of Environmental Health (September/October). National Institute for Environmental Health Sciences (NIEHS). 2001. Ninth National Toxi- cology Program Report on Carcinogens. Online. Available at 18.104.22.168/roc/ninth/ rahc/diesel.pdf. Accessed August 29, 2002. National Institute for Occupational Safety and Health (NIOSH). 1988. Carcinogenic effects of exposure to diesel exhaust. NIOSH Current Intelligence Bulletin 50. DHHS (NIOSH) Publication No. 88-116. Centers for Disease Control, Atlanta. Project of China Environment Technological Assistance Loaned by the World Bank B-9-3. 1997. Strategy Analysis of Vehicular Emission Pollution Control in China (Summary Report). Environmental Engineering Department, Tsinghua University, Beijing, Octo- ber. Shanghai Municipal Government. 1999. Strategy for Sustainable Development of Urban Transportation and Environmentâfor a Metropolis with Coordinating Development of Transportation and Environment toward the 21st Century. Shao M., Zhang Y., and R. Raufer. 2001. Control strategies for NOx emissions in Guangzhou, China. Natural Resources Forum 25(2):157â165. Shine, K. P., R. G. Derwent, D. J. Wuebbles, and J. J. Morcrette. 1990. Radiative forcing of climate. In Climate Change, the IPCC Scientific Assessment, J. T. Houghton, G. J. Jenkins, and J. J. Ephraums, eds. Cambridge: Cambridge University Press. U.S. Environmental Protection Agency (U.S. EPA). 1985. Mutagenicity and carcinogenicity assessment of 1,3-butadiene. EPA Report No. EPA/600/8-85/004F. Office of Health and Environmental Assessment, EPA, Washington, D.C. âââ. 1987. Assessment of Health Risks to Garment Workers and Certain Home Residents from Exposure to Formaldehyde. Office of Pesticides and Toxic Substances, EPA, Wash- ington, D.C., April. âââ. 1993a. Air Quality Criteria for Oxides of Nitrogen. EPA Report No. EPA/600/8-91/ 049aF. Washington, D.C.
168 PERSONAL CARS AND CHINA âââ. 1993b. Motor Vehicle-Related Air Toxics Study. EPA Report No. EPA 420-R-93-005. Office of Mobile Sources, EPA, Ann Arbor, Mich., April. âââ. 1995. Review of National Ambient Air Quality Standards for Nitrogen Dioxide, As- sessment of Scientific and Technical Information. OAQPS Staff Paper. EPA-452/R-95- 005. Office of Air Quality Planning and Standards, EPA, Washington, D.C. âââ. 1996a. Air Quality Criteria for Ozone and Related Photochemical Oxidants. EPA Report No. EPA/600/P-93/004aF. Washington, D.C. âââ. 1996b. Air Quality Criteria for Particulate Matter. EPA Report No. EPA/600/P-95/ 001aF. Washington, D.C. âââ. 1996c. Review of National Ambient Air Quality Standards for Ozone, Assessment of Scientific and Technical Information. OAQPS Staff Paper. EPA-452/R-96-007. Office of Air Quality Planning and Standards, EPA,Washington, D.C. âââ. 1998. Carcinogenic Effects of Benzene: An Update. EPA Report No. EPA/600/P-97/ 001F. National Center for Environmental Assessment, EPA, Washington, D.C. âââ. 2000. Air Quality Criteria for Carbon Monoxide. Office of Research and Develop- ment, EPA, Washington, D.C., June. World Health Organization (WHO). 1996. Diesel Fuel and Exhaust Emissions: International Program on Chemical Safety. Geneva, Switzerland.