China's Health and Environment:
Air Pollution and Health Effects

Smoke Pollution in China

Poor Ambient Air Quality Prevails
China's Air Pollution Levels Are Among the World's Highest
China's Growing Consumption of Coal
Outdated Vehicles Degrade Urban Air Quality
Health Effects from Ambient and Indoor Air Pollution
Air Pollution's Toll
Air Quality May Be Worse Indoors


Poor Ambient Air Quality Prevails

"The residents of many of China's largest cities are living under long-term, harmful air quality conditions," Zhao Weijun, deputy director of the air pollution department of NEPA, reported in 1997 in China Environment News [16]. China has long recognized air pollution as a critical problem. Ambient concentrations of total suspended particulates (TSP) and sulfur dioxide (SO2) are among the world's highest. (See China's Air Pollution Levels Are Among the World's Highest.) In 1995, more than one half of the 88 cities monitored for SO2 were above the World Health Organization (WHO) guideline. All but two of the 87 cities monitored for TSP far exceeded WHO's guideline. Some cities such as Taiyuan and Lanzhou had SO2 levels almost 10 times the WHO guideline [17].

Largely because of controls at power plants and within households, particulate emissions have not risen as much as might have been expected with the doubling of coal consumption. Overall, particulate emissions in China have remained relatively level since the early 1980s [18]. In fact, in some large cities, ambient particulate concentrations have decreased markedly since the 1980s [19]. In contrast, SO2 emissions have roughly paralleled the increase in coal consumption, reflecting heavy coal burning and inadequate sulfur control measures.

Coal burning, the primary source of China's high SO2 emissions, accounts for more than three quarters of the country's commercial energy needs, compared with 17 percent in Japan and a world average of 27 percent [20]. China's consumption of raw coal increased annually by 2 percent between 1989 and 1993 [21]. (See China's Growing Consumption of Coal.) Meanwhile, SO2 emissions increased by more than 20 percent and TSP increased by approximately 10 percent [22]. The country is expected to burn 1.5 billion metric tons of coal annually by the year 2000, up from 0.99 billion metric tons in 1990 [23]. Without even more dramatic measures to control emissions than are currently in place, the deterioration of air quality seems inevitable.

China's Air Pollution Levels Are Among the World's Highest
Ambient Concentrations of Air Pollutants, 1995


Source: The World Bank, Clear Water, Blue Skies: China's Environment in the New Century (The World Bank, Washington, D.C., 1997), Figure 1.1, p. 6.
China's Growing Consumption of Coal
Energy Demand in China, 1971-95
Source: International Energy Agency, Energy Statistics and Balances: Non-OECD Countries, 1971-1995, on diskette (Organisation for Economic Co-Operation and Development, Paris, 1997).

Particulates and SO2 are the ambient air pollutants of greatest concern; both are byproducts of coal combustion. While industrial emissions of heavy metals and toxics are also significant contributors to air pollution in China, they are not routinely monitored and will not be addressed in this section.

The extent and type of air pollution in China vary dramatically by geographic region. SO2 and particulate emissions are highest in the northern half of China, where coal is used to heat homes and other buildings for several months of the year and where industrial centers also depend heavily on coal burning. Yet, air pollution in the North would be much worse if not for the higher quality, cleaner coal that is available there. By contrast, the coal mined in the South is high in sulfur and extremely polluting, contributing to serious problems with acid precipitation, especially in the southwest provinces of Sichuan, Guizhou, Guangxi, and Hunan [24] [25].

Industry accounts for two thirds of China's coal use -- industrial boilers alone consume 30 percent of China's coal. These boilers are usually highly inefficient and emit through low smoke stacks, contributing to much of China's ground-level air pollution, especially small particulates and SO2. Inefficient and dirty boilers are particularly problematic because many of the industries that use them are located in densely populated metropolitan areas, placing populations in these areas at high risk of exposure. The residential sector accounts for approximately 15 percent of total coal use, yet is estimated to contribute to more than 30 percent of urban ground-level air pollution [26] [27].

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].

Outdated Vehicles Degrade Urban Air Quality
Percentage of Emissions in Selected Chinese Cities Attributable to Motor Vehicles

  PERCENTAGE ATTRIBUTABLE TO MOTOR VEHICLES
  CARBON MONOXIDE HYDROCARBONS NITROUS OXIDES CATEGORIES

Beijing

48-64

60-74

10-22

District

Shanghai

69

37

 

District

Shenyang

27-38

 

45-53

District

Jinan

28

 

4-6

District

Hangzhou

24-70

   

Road

Urumqi

12-50

   

Road

Guangzhou

70

 

43

 


Source: He et al., "Status and Development of Vehicular Pollution in China," Environmental Science, Vol. 7, No. 4 (August 1996).


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.


Health Effects from Ambient and Indoor Air Pollution

Air Pollution's Toll
Estimates of Respiratory Damage That Could Be Avoided by Meeting Class 2 Air Quality Standards in China
PROBLEM NUMBER OF CASES AVERTED

Urban air pollution
Premature deaths 178,000
Respiratory hospital admissions 346,000
Emergency room visits 6,779,000
Lower respiratory infections or child asthma 661,000
Asthma attacks 75,107,000
Chronic bronchitis 1,762,000
Respiratory symptoms 5,270,175,000
Restricted activity days (years) 4,537,000

Indoor air pollution
Premature deaths 111,000
Respiratory hospital admissions 220,000
Emergency room visits 4,310,000
Lower respiratory infections or child asthma 420,000
Asthma attacks 47,755
Chronic bronchitis 1,121,000
Respiratory symptoms 3,322,631,000
Restricted activity days (years) 2,885,000

Source: The World Bank, Clear Water, Blue Skies: China's Environment in the New Century (The World Bank, Washington, D.C., 1997), Table 2.1, p. 19.

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].

Indoor air pollution affects both urban and rural populations. Nor is it simply a problem indoors: numerous studies have shown that intense indoor coal burning can affect ambient air quality as well. For instance, rural neighborhoods are generally unaffected by urban sources of air pollutants but can be extremely polluted from the burning of coal indoors. Air Quality May be Worse Indoors shows the extremely high levels of particulates in both rural and urban indoor environments [39]. Indoor air pollution causes as many health problems as smoking, with the effects concentrated among women and children [40].

Although the proportion of China's households that burn polluting biomass fuels indoors for cooking and heating remains significant, it has been declining with the proliferation of alternative energy sources. Largely as a result of government investments, about one third of urban Chinese now have access to gas for cooking, and coal-burning households are increasingly turning to the use of cleaner, more efficient briquettes [41].

Perhaps the most compelling example of the health impact from indoor air pollution is the extremely high lung cancer rates among nonsmoking women in rural Xuan Wei County. Studies conducted by the United States Environmental Protection Agency (U.S. EPA) report that in the three communes with the highest mortality rates, the age-adjusted lung cancer mortality rate between 1973 and 1979 was 125.6 per 100,000 women, compared with average rates of 3.2 and 6.3 for Chinese and U.S. women, respectively, for the same time. Because surveys showed that virtually no women (in the county) smoked tobacco products, other sources of potent exposure must have contributed to these troubling rates. Analyses of indoor air and blood samples from the women indicate that fuel burning inside the home was largely responsible for the lung cancers. The U.S. EPA studies found a strong association between the existence of lung cancer in females and the duration of time spent cooking food indoors. The levels of carcinogenic compounds present in smoky coal (a local type of coal that smokes copiously) were found to be much higher in the women who used smoky coal for cooking [42] [43].

Air Quality May be Worse Indoors
Indoor Air Particulate Air Pollution from Coal Burning in China (Sample Studies)
PLACE URBAN/RURAL PARTICULATES (micrograms per cubic meter)
Shanghai Urban 500-1,000
Beijing Urban 17-1,100a
Shenyang Urban 125-270
Taiyuan Urban 300-1,000
Harbin Urban 390-610a
Guangzhou Urban 460
Chengde Urban 270-700a
Yunnan Rural 270-5,100
Beijing Rural 400-1,300
Jilin Rural 1,000-1,200a
Hebei Rural 1,900-2,500
Inner Mongolia Rural 400-1,600a

Source: World Health Organization (WHO), Health and Environment in Sustainable Development: Five Years after the Earth Summit (WHO, Geneva, 1997), p. 86.

Note: a. Particles less than 10 micrometers in size.


Since the 1980s, a number of studies examining the relationship between ambient air pollution and health effects in China have been conducted. It is important to remember that although the studies measured only ambient air pollution levels, in reality people are exposed to a combination of indoor and outdoor air. One of most definitive of these studies examined the relationship between air pollution and mortality in two residential areas of Beijing. According to this study, the risk of mortality was estimated to increase by 11 percent with each doubling of SO2 concentration, and by 4 percent with each doubling of TSP. When the specific causes of mortality were examined, mortality from COPD increased 38 percent with a doubling of particulate levels and 29 percent with doubling of SO2. Pulmonary heart disease mortality also increased significantly with higher pollution levels. Levels of air pollution measured often exceeded WHO guidelines, particularly in winter when ambient air pollution was exacerbated by indoor fuel burning and climatic conditions. Yet, what was striking is that excess mortality was associated with pollutant levels below WHO guidelines, suggesting that the guidelines cannot be perceived as a safe limit [44].

Respiratory diseases, hospitalization, or doctor visits are often a more sensitive measure of the impact of air pollution on human health than mortality. One recent study confirmed that as concentrations of SO2 and TSP rose in Beijing, so did visits to the emergency room. This increase in unscheduled hospital visits occurred both when air pollution levels were extremely high (primarily in the winter) and when the levels were below WHO's recommended guidelines, bolstering studies in developed countries that have shown excess respiratory disease and mortality at lower doses [45]. Although Beijing has been the focus of many studies, it has no monopoly on bad air. Chongqing, the largest and most recently declared autonomous zone, has a higher concentration of SO2 than any of China's five other largest cities [46]. A recent study found that several symptoms of compromised health, including reduced pulmonary function and increased mortality, hospital admissions, and emergency room visits, were correlated with higher levels of air pollution in Chongqing [47]. A study conducted in another of China's largest cities, Shenyang, estimated total mortality increased by 2 percent with each 100 micrograms per cubic meter increase in SO2 concentration, and by 1 percent for each 100 micrograms per cubic meter in TSP [48].

Respiratory diseases are not the only health impacts of concern associated with air pollution. Lead exposure, for instance, leads to neurological damage, particularly in children. China has no comprehensive national data on blood-lead levels, a reliable biomarker of exposure, but some studies show that blood-lead levels are far above the threshold associated with impaired intelligence, neurobehavioral development, and physical growth. (The U.S. standard is 10 micrograms per deciliter.) Between 65 and 100 percent of children in Shanghai have blood-lead levels greater than 10 micrograms per deciliter. Those in industrialized or congested areas had levels averaging between 21 and 67 deciliters [49]. In Shanghai, prenatal exposures to lead from urban air were associated with adverse development in the children during their first year of life [50].


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