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[YOGYAKARTA] Air pollution from ozone and soot over Asia is twice the global average and is especially strong over tropical regions, a scientist told government representatives of 20 Asian countries at a meeting last week.

India is emerging as a 'hotspot for ozone pollution', and in China pollution is rising, said Surabi Menon of the Lawrence Berkley National Laboratory, United States.

Her warnings echoed other reports of deteriorating air quality in Asia at the Urban Air Quality in Asia workshop in Yogyakarta, Indonesia.

The meeting ended with a pledge — albeit non-binding — that the 20 nations would improve their air quality control programmes.

According to Menon, emissions of sulphur dioxide and nitrogen oxides in China and Korea will exceed World Health Organization (WHO) air quality standards by 2020.

Industry, transport and incomplete fossil fuel combustion are the main culprits. The gases cause acid rain, are toxic to health, and contribute to the formation of ozone in the lower layers of the atmosphere.

Ozone is a paradox. In the upper atmosphere — the stratosphere — it is known as 'good' ozone, as it protects the earth from harmful ultraviolet light from the sun.

But in the lower layer — known as the troposphere — which extends up to two kilometres above sea level, ozone from car exhausts and industry is 'bad' as it damages human health and vegetation.

Computer simulations show that the yearly increase in ozone levels in India, currently at 12 parts per billion, could exceed 25-30 parts per billion, said Menon. 

Soot emissions from China continue to be large, at 2.3 terragrams annually, compared to 0.053 terragrams in Japan.

'The health and air quality issues will become increasingly important for Asia,' Menon told SciDev.Net.

Soot and other polluting particles released by industries and biofuels have important climate effects, especially over Asia, she said.

In 2002, Menon and colleagues showed that soot heats the air, affecting rainfall patterns over China (see 'Asian soot fuels global warming').

Other scientists at the meeting also warned of the poor air quality in most Asian cities. Michal Kryazanoski, a senior official at the WHO, said that air pollution exceeding WHO guidelines causes more than 500,000 premature deaths in Asia annually.

Most Asian cities do not have adequate air quality monitoring stations and emissions inventories are either lacking, incomplete or contradictory, according to a report by the Stockholm Environment Institute.

The Asian Development Bank showed that a major cause for deteriorating air quality is rise in road traffic. It warned that even with the most optimistic estimates for managing the rise in vehicle use in Asia, emissions of carbon dioxide are expected to treble over the next 25 years.

The conference was organised by the Clean Air Initiative for Asian Cities, the Indonesian Ministry of Environment, the UN Centre for Regional Development and the UN Environment Program.