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Air quality

Air pollution levels in the most populated cities are amongst the highest in the world, producing serious human health impacts and affecting aquatic and terrestrial ecosystems. Transport is a significant, often major, source of urban air pollution. The other sources include industrial emissions, burning of solid and liquid fuels for power generation, and burning of biomass and other fuels such as charcoal for household use. In a few cities, pollution levels have decreased. For example, in Japan, high fuel prices, technological advances and strict standards have reduced SO2 and particulate emissions, and eliminated lead emissions from transport. However, NOx emissions in Tokyo and Osaka have not declined sufficiently because of an increasing number of vehicles. This situation is common in cities with growing levels of private transport (UN-ESCAP/ADB 2000).

Passenger vehicles/1 000 people (1996)

Despite the heavy air pollution in Asia's cities, the number of vehicles per capita is well below the global average in all sub-regions except Australia and New Zealand

Source: World Bank 2000

Traffic has become a major air polluter in the big cities, although most Asian countries have low per capita vehicle ownership in comparison to the world average (World Bank 2000). However, the motorized fleet (see bar chart) has been growing rapidly; for example, the number of private motor vehicles in Sri Lanka doubled during 1975-92 (Government of Sri Lanka 1994) and in India the number of cars has been doubling every seven years for the past 30 years (ADB 1999). This fact, combined with poor roads, fuel quality and vehicle maintenance, makes vehicular air pollution an alarming issue.

Many countries have developed their own air quality standards for principal pollutants as well as emission standards for power plants, selected industries and vehicles. To reduce pollution, many countries have introduced unleaded petrol, mandatory catalytic converters and low sulphur motor fuels. Alternative technologies such as electric vehicles and compressed natural gas operated vehicles are also being considered, especially in India and the Islamic Republic of Iran. Tax incentives for gas or battery operated vehicles have been introduced in Nepal and Pakistan.

Except for developed countries of the Northeast Asian and parts of the South Pacific sub-regions, concern over the environment began to create a demand for improved environmental protection in the 1980s. The 1990s have seen significant progress in establishing the institutions and policy tools needed to address urgent environmental problems. However, continuous growth in energy consumption and reliance on fuels such as coal and oil with a relatively high carbon content will inevitably increase emissions unless more aggressive policies are introduced.

Urban air pollution in Asia
The air in Asia's cities is amongst the most polluted in the world. Of the 15 cities in the world with the highest levels of particulate matter, 12 are located in Asia (ADB 1999). Furthermore, six of these cities also have the highest levels of atmospheric SO2. Levels of air pollution substantially exceed the international guidelines for air quality recommended by WHO. Cities such as Beijing, Calcutta, Jakarta, New Delhi, Shanghai and Tehran are notorious for high levels of suspended particulates, with New Delhi recording the maximum of 420 µg/m3 (ESCAP/ADB 2000 and ADB 2001). Tehran has also recorded SO2 levels four times the guidelines prescribed by WHO (World Bank 2001).

Indoor air pollution is often a more severe health hazard than outdoor air pollution. Most rural inhabitants in the region use twigs, grass, dried animal dung, crop residues, wood, charcoal and kerosene as household fuels. Coupled with inadequate ventilation, this results in highly contaminated indoor air. Given the high levels of harmful emissions and the number of people using traditional cooking fuels - Asia produces nearly half of the world's woodfuel (FAOSTAT 2001) - the scale of exposure is large. Health effects include acute respiratory infection in children, chronic obstructive lung disease, adverse pregnancy outcomes and lung cancer in women. Acute respiratory diseases are prevalent in the rural and/or hilly areas of Afghanistan, Bangladesh, Bhutan, India, Nepal, Pakistan and Sri Lanka where indoor air pollution is high. About 40 per cent of the global infantile mortality caused by pneumonia occurs in Bangladesh, India, Indonesia and Nepal; many of these deaths are caused by pollutants from burning traditional fuels (ADB 2001). In India, household solid fuel use is estimated to cause about 500 000 premature deaths a year in women and children under five. There are indications that tuberculosis and blindness may be associated with indoor air pollution. Indoor air pollution is blamed for 5-6 per cent of the national burden of diseases in women and children in India (Holdren and Smith 2000).

The key areas for intervention are: use of cleaner fuels such as low-propane gas and kerosene; development of high-grade biomass fuels; improvements in stove design and better dissemination of stoves; improvements in housing; and improvements in environmental awareness and education. To address the problem of indoor air pollution in India, around 3 million biogas plants and more than 22 million improved cooking stoves have been installed in rural and remote areas of the country, resulting in a saving of the equivalent of 21 million tonnes of firewood per annum (Times of India 2000).

Haze and acid rain have been the emerging regional issues over the past decade, especially in Asia because of China and India's overwhelming dependence on coal. Around 0.28 million ha of forest land are reported to be damaged by acid rain in the Sichuan basin of China. SO2 emissions in Asia are estimated to have increased from about 26.6 to about 39.2 million tonnes during 1985-1997 (Streets and others 2000). In China, a reduction of 3.7 million tonnes or 15.8 per cent in SO2 emissions was achieved during 1995-2000 (SEPA 2001). At least two-thirds of acid depositions in the region are caused by coal-fired power plants with outdated pollution control equipment.

The Asian brown cloud

In spring 1999, scientists working on the project Indian Ocean Experiment (INDOEX) discovered a dense brownish pollution haze layer covering most of South and Southeast Asia and the tropical region of the Indian Ocean. The researchers tracked the haze over an area of about 10 million km2, and believe it forms over much of the Asian continent. The haze is a mixture of pollutants, mainly soot, sulphates, nitrates, organic particles, fly ash and mineral dust, formed by fossil fuel combustion and rural biomass burning. It reduces the sunlight reaching the tropical Indian Ocean surface, thousands of kilometres from its source, by as much as 10 per cent, with a larger reduction over the Indian sub-continent. Simulations with global climate models indicate that the haze could have major impacts on the monsoon circulation, regional rainfall patterns and vertical temperature profile of the atmosphere.

A programme called ABC (Asian Brown Cloud) has been initiated with support from UNEP. The main aim of the first phase of this programme is to study the impact of the Asian haze on a number of parameters, including monsoon change, water balance, agriculture and health. Scientists plan to establish a network of ground-based monitoring stations throughout Asia to study the composition and seasonal pattern of the haze. UNEP has pledged to facilitate the continued research programme and, in the longer-term, to help coordinate policy responses to address the problem.

Source: UNEP (2001) and C4 and UNEP (in press)

Haze problems are also prevalent in the region due to forest fires in Southeast Asia. The most serious episode occurred in 1997, when the effects of forest fires in Indonesia extended to neighbouring countries including Brunei Darussalam, Papua New Guinea, Philippines, Singapore and Thailand (UNEP 1999). A Haze Technical Task Force was established by ASEAN Senior Officials on Environment in 1995 and, in 1997, a Regional Haze Action Plan was approved (ASEAN 2001).

The Acid Deposition Monitoring Network (EANET), with the participation of ten East Asian countries, began a preparatory phase of monitoring acid deposition in April 1998. In October 2000, the network decided to begin regular monitoring from January 2001 (EANET 2000). In South Asia, the Malé Declaration on Control and Prevention of Air Pollution and its likely Transboundary Effects, was adopted by eight South Asian countries in 1998.