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Although the energy and industrial sectors are now the biggest contributors to urban air pollution in China, the transportation sector is becoming increasingly important. The number of motor vehicles on China’s roads has tripled since 1984, climbing from less than 2.4 million in 1984 to 9.4 million in 1994 [28]. By 2020, the urban vehicle population is expected to be 13 to 22 times greater than it is today [29]. This trend will likely have a major influence on the future of China’s air quality. The shift toward vehicle use is most apparent in China’s big cities. For example, from 1986 to 1996, the number of vehicles in Beijing increased fourfold, from 260,000 to 1.1 million. Although this is only one tenth of the number of vehicles in Tokyo or Los Angeles, the pollution generated by Beijing motor vehicles equals that in each of the two other cities [30].
The problem stems not just from the growing size of the vehicle fleet but also from low emissions standards, poor road infrastructure, and outdated technology, which combine to make Chinese vehicles among the most polluting in the world [31]. Vehicle emissions standards in China are equivalent to the standards of the developed world during the 1970s, and some domestic companies are manufacturing vehicles modeled after vehicles from 20 years ago. Actual emissions often exceed these standards: Chinese vehicles emit 2.5 to 7.5 times more hydrocarbons, 2 to 7 times more nitrous oxides (N2O), and 6 to 12 times more carbon monoxide (CO) than foreign vehicles [32]. In Beijing, Shanghai, Hangzhou, and Guangzhou, up to 70 percent of CO emissions have been attributed to motor vehicles. Cars also contribute a large share of hydrocarbons and N2O in the cities where data are available [33]. (See Outdated Vehicles Degrade Urban Air Quality.) As a result, although China’s vehicle fleet is small compared with the developed countries, its large cities are already blanketed with smog.
A recent study in Beijing revealed that at all monitoring points within the Third Ring Road – a rough boundary separating downtown Beijing and its outskirts – the CO levels exceeded the national standard (4 micrograms per cubic meter per day). During the summer, ozone concentrations repeatedly exceeded the national standard, which is set on an hourly basis – often several times per day. In addition, concentrations of N2O have almost doubled over the past decade [34].
Compounding these pollution problems is the fact that the burgeoning Chinese motor vehicle fleet is largely fueled by leaded gasoline. Although lead exposure is known to be a significant health hazard in China, no routine monitoring of environmental concentrations or blood- lead levels is performed. A few studies have been conducted and are described below. These scanty data suggest that ambient lead levels in the urban area of major cities such as Beijing are usually 1 to 1.5 micrograms per cubic meter – the national standard is 1 microgram per cubic meter. In some areas, ambient lead levels can reach as high as 14 to 25 micrograms per cubic meter [35]. The health effects, described below, are significant, although recent and dramatic government actions to phase out leaded gasoline will likely have a major impact on this problem. Beijing and Shanghai as well as other cities have already begun to act, and the countrywide phaseout is expected to be complete by the year 2000.
Air pollution is thought to be one of the leading risk factors for respiratory diseases, such as chronic obstructive pulmonary disease (COPD), lung cancer, pulmonary heart disease, and bronchitis, diseases that are the leading causes of death in China. The fact that men and woman have similar rates of these diseases, despite women’s much lower smoking rates, provides evidence that this high disease burden is related to pollution [36].
Although only a limited number of epidemiologic studies have been conducted, air pollution has clearly contributed to both excess mortality and morbidity in China. At this stage, however, it is extremely difficult to tease apart which sources of air pollution have the greatest impact on human health, indoor or outdoor. In urban areas, there is a great deal of exchange between outdoor and indoor air, both of which are polluted from different sources – indoor primarily from the burning of coal for cooking and heating. Summaries of selected recent estimates of health impacts are presented to provide a more complete understanding of the complex relationship between air pollution and human health.
Based on dose-response functions from studies conducted within China and in other countries, the World Bank has estimated the number of deaths and diseases associated with air pollution among urban populations. Using the Chinese standards as a benchmark, they estimate the number of deaths that could be prevented if air pollution were reduced to those levels. According to their calculations, approximately 178,000 deaths, or 7 percent of all deaths in urban areas, could be prevented each year. Another measure of air pollution’s impact on health is the number of hospital admissions from respiratory diseases. This study found 346,000 hospitalizations associated with the excess levels of air pollution in urban areas. Air Pollution’s Toll summarizes the estimated health impact of both ambient and indoor air pollution in China [37].
In China, the effects of outdoor air pollution are compounded by those of indoor air pollution. Households using coal for domestic cooking and heating are especially at risk because coal emits very high levels of indoor particulate matter less than 2.5 microns in size – the size believed to be most hazardous to health. (These concentrations can be more than 100 times the proposed U.S. ambient air 24-hour standard.) Exposure to these small-sized particles is especially harmful because they persist in the environment and reach deep into the lungs [38].
28 American Automobile Manufacturers Association @Box Ref = (AAMA), Motor Vehicle. Facts and Figures (AAMA, Washington, D.C., 1996) pp. 44<196>47.
29. Stephen Stares and Liu Zhi, “Motorization in Chinese Cities: Issues and Actions,” in China’s Urban Transport Development Strategy: Proceedings of a Symposium in Beijing, November 8<196>10, 1995, World Bank Discussion Paper No. 352 (The World Bank, Washington, D.C., 1996), p. 50.
30. Liu Xianshu and Xiao Ynxiang, “How to Enjoy and Use Automobiles,” China Environment News (January 28, 1997, Beijing), p. 1.
31. Michael Walsh, “Motor Vehicle Pollution in China: An Urban Challenge,” in China’s Urban Transport Development Strategy: Proceedings of a Symposium in Beijing, November 8<196>10, 1995, World Bank Discussion Paper No. 352 (The World Bank, Washington, D.C., 1996), pp. 118<196>122.
32. He Kebin et al., “The Status and Trend of Urban Vehicular Pollution,” Environmental Science, Vol. 17, No. 4 (1996), pp. 80<196>83 (in Chinese).
33. He Kebin et al., “Status and Developments in China’s Vehicle Emissions Pollution,” Environmental Science, Vol. 7, No. 4 (1996), pp. 15<196>17 (in Chinese).
34. Ibid.
35. Op. cit. 31, p. 120.
36. Op. cit. 12, pp. 17<196>18.
37. Op. cit. 12, p. 19, Table 2.1.
38. World Health Organization (WHO), Health and Environment in Sustainable Development: Five Years After the Earth Summit (WHO, Geneva, 1997), p. 82.