The developing countries of Asia and the Pacific region have been developing more rapidly than all other developing countries in the world for the last three decades; this trend is likely to continue in the future. One of the more important implications of economic growth in the region has been the increased demand for energy. The Asia and the Pacific region, excluding Japan, Australia and New Zealand, accounted for 21 per cent of the world’s primary commercial energy demand in 1992 (Figure 1.13). A growth in energy demand of 3.6 per cent per year for the whole region was maintained between 1990 and 1992, compared with an average growth of 0.1 per cent for the whole world (ADB, 1994b). The region also accounts for about 41 per cent of the global consumption of coal in 1993 (EIA, 1995). The rapid growth in energy demand, and especially the reliance on coal, has led to a significant increase in the emissions of air pollutants wherever appropriate technology interventions are not made (such as scrubbers). 

A survey by the World Health Organization (WHO) and UNEP of the urban air quality in 11 cities in the region revealed that 10 had dangerous levels of suspended particulate matter (SPM) exceeding WHO guidelines by more than a factor of two. Problems of SO₂, lead and SPM pollution are prevalent in many cities of the region (Table 7) (WHO/UNEP, 1992). In addition to the megacities, there are a large number of medium and small cities in the region that have serious problems resulting from their development as industrial centres. Beijing has become one of the world’s most polluted capitals — the air is 35 times more polluted than that of London and 16 times more contaminated than in Tokyo. Air pollution is expected to increase in Seoul, Taipei, Jakarta, Kuala Lumpur and Bangkok between the years 1991 and 2000 (Asiaweek, 1996). The greatest pollution-related threat to health comes from the use of low quality solid fuels, such as coal, wood, crop residues and dung for cooking and heating in lower income urban households and in rural areas throughout the region. 

The problem of fly ash occurs naturally from volcanic activity and from the burning of some varieties of coal. Fly ash generated from the mining of coal is also a significant problem in the region, particularly in India where it is as serious a problem as acid rain is elsewhere. It is estimated that 35–40 million tonnes of fly ash is generated by thermal power plants every year and that only 2–3 per cent is being reused (Government of India, 1993). The quantity of fly ash requiring disposal can be reduced by better washing techniques or it can be reused as fertilizer, to make bricks and roads, or to replace sand used to refill mines. These activities are being promoted by the government of India to help address the fly ash problem. 

Economic growth and energy consumption as discussed above lead to problems of trans-boundary air pollution. The effects of coal burning spread over a large area and result in acid deposition in the vicinity of the coal burning plants as well as further away. The accumulation of fly ash adds to air quality deterioration by increasing SPM levels. Slash and burn agriculture can also lead to poor air quality (haze) that extends beyond national boundaries. 

The discussion above presents a poor image of atmospheric conditions in the Asia-Pacific region. However, it is important to note that there are numerous ongoing national and regional initiatives to bring these problems under control. 

Vehicular emissions are a significant problem in all major cities. The government of the Philippines is attempting to address this issue through plans to limit the number of vehicles on the road. Similar measures are also being taken in Thailand. India has implemented programmes setting emission standards for vehicles on the road as well as requiring manufacturers to meet strict emission standards for all new vehicles. Significant penalties are imposed on violators. In several countries, including the Philippines, unleaded petrol has been introduced widely and new vehicles are required to be able to run on this fuel. The use of gasohol (and other petroleum substitutes) and electric cars, and other experiments, are also ongoing in many countries in the region. 

It is crucial that the governments, the energy sector planners and the environmental managers consider these increasingly severe air pollution impacts in their strategies and specific investment plans in order to avoid future problems in a decade or less. 

Although, until recently, acidification of the environment has been regarded as a problem only in Europe and North America, it has also started to emerge in parts of the Asia-Pacific region. Increased emissions of sulphur dioxide (SO₂) as a result of human activities are the major precursor of acid rain. Prevailing winds transport acidic compounds, sometimes hundreds of kilometres, within the country and across national borders (see Box 1.1). 

It has been estimated that the total emissions of SO₂ in 22 countries of Asia were 38 million tonnes in 1990, almost 56 per cent higher than that of North America, and that they would be much higher in the coming decades if effective mitigation measures are not adopted (Shrestha et al., 1996). About 78 per cent of these emissions originated from North-East Asia (i.e. People’s Republic of China, Republic of Korea, Japan, Hong Kong, Mongolia and Chinese Taipei). A study sponsored by the World Bank and the Asian Development Bank on "Acid Rain and Emissions Reduction in Asia" showed that the areas with the lowest critical loads (i.e. up to 320 milligrams per square metre per year) and which are therefore most sensitive to acidic deposition, are located in South China and in the areas covering the South-East of Thailand, Cambodia and South Vietnam. Critical loads are the maximum allowable deposition levels (of a substance) that will not lead to damage to the ecosystem. Critical loads vary from area to area and are influenced by topography, geology, climate and many other factors. 

Acid rain has a significant potential to affect the environment in the Asia-Pacific region. However, at present there is not sufficiently strong scientifric or public pressure for action to mitigate the potential effects of acidification in the region. Inaction could result in serious damage to ecosystems and materials. Thus, research should be intensified on the emissions of air pollutants and their trans-boundary effects, on the assessment of damage to ecosystems, and on mitigation strategies in the region. A sulphur protocol should also be developed in the Asia-Pacific region. 

Transboundary issues are complicated scientifically as well as politically. To date very little scientific study has been carried out on this issue. This trend is, however, changing because studies have been initiated on several significant transboundary pollution problems. There have been some efforts to study the creation and flow of acid rain, such as the RAINS-ASIA programme and computer model, as well as the Asia Least-Cost Greenhouse Gas Abatement Strategy (ALGAS) which is examining measures for mitigating the effects of greenhouse gases. 

It is clear that while problems do exist and are significant, there is a concerted effort at the national, regional and global levels to address these problems and to bring about effective and viable solutions as soon as possible.