20 Asian cities rated for air pollution

By Anumita Roychowdhury
Published: Monday 15 January 2007

New monitors: Smog rises in Be in contrast to the conventional practice of rating cities only on the basis of air pollution, a new study has benchmarked 20 Asian cities on their ability to manage air quality. The report, Urban Air Pollution in Asian Cities, brought out by the Clean Air Initiative for Asian cities and the Sweden-based Stockholm Environment Institute was introduced at a recent conference on better air quality in Yogyakarta, Indonesia. Experts say the report can be the basis of measuring future initiatives and progress of cities.

Among the three Indian cities considered for the study, New Delhi figures in the fourth grade, labelled Good ii. Kolkata and Mumbai are ranked lower for their poorer pollution management capacity. Bangkok, Beijing, Colombo, Dhaka, Ho Chi Minh City, Hong Kong, Kathmandu, Seoul, Shanghai, Singapore and Tokyo have also been assessed. The study has classified cities into five classes based on pollution trends and pollution management capacities. The results show wide variations among Asian cities.

The report also notes that though the ability to manage air quality has improved in Asia since the 1990s, air quality in most of the cities examined still exceeds international guidelines for certain pollutants.

Predictably, the developed cities--Singapore, Hong Kong, Taipei, Tokyo, Bangkok, Seoul, and Shanghai--have made it to the excellent rank of i and ii. The rapidly growing cities of Beijing, Busan and New Delhi are termed good. Next in the rung are the moderates-- Ho Chi Minh city, Jakarta, Kolkata, Metro Manila, and Mumbai. The cities with limited management capacity like Surabaya and Kathmandu are also among the most polluted.

Contrary to expectations, cities with excellent air quality management capabilities do not always equate in low air pollution concentration. For instance, Shanghai, which is ranked excellent for air quality management, has serious particulate pollution with moderate levels of no2 and so2. The particulate pollution has remained obstinately stable in these cities despite the strong management capabilities. Other cities with poorer air quality management capability and serious particulate pollution face an even greater challenge.

The region has succeeded in the overall stabilisation of so2 at a relatively low level. But the use of high sulphur fuel content in some countries has increased emissions. Emissions of no2 and fine particulate matter, mainly from the transport sector, are a cause of serious concern.

Commenting on the ranking methodology, Dieter Schwela, noted air pollution scientist and one of the co-authors of the study, said that ranking of cities only on the basis of air pollution is "scientifically unsound, as cities that are not monitoring are not included in ranking exercise and cities with high annual mean and low percentile cannot be ranked against cities with low annual mean and high percentile". Therefore, the study chose to classify cities in terms of their management capabilities in clusters, but not ranked.

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