Saturday, January 26, 2008

Air pollution in mega cities in China: A Review

Air pollution (both gas and particle) in Chinese mega cities is one of the biggest growing problems due to rapid increase in industrial activities in the area. A review article on air pollution in China entitled “Air pollution in mega cities in China” by Chan and Yao is published in January 2008 issue of Atmospheric Environment. This article provides through review of available literature on air pollution research in China and focused areas are Beijing, Shanghai, and the Pearl River Delta region.

Here, I am providing some highlights of the article. Please refer original article for more details.

"Air pollution has become one of the top environmental concerns in China. Currently, Beijing, Shanghai, and the Pearl River Delta region including Guangzhou, Shenzhen and Hong Kong, and their immediate vicinities are the most economically vibrant regions in China.”

Air quality in most Chinese cities has improved despite the rapid growth of the economy…, however… He et al. (2001) and Ye et al. (2003) reported that PM2.5 concentrations in Beijing and Shanghai, the two largest cities in China, were about 10 times and six times the WHO guideline values, respectively.”

“From 1980 to 2005, the urban population in China increased from 19.6 to 40.5%. The number of cities increased to over 660, and more than 170 cities had over 1 million permanent residents (not including the migrant population) in 2004.”

“Much attention has been paid to reducing emissions, particularly vehicle emissions. Although the number of vehicles has increased by about 10% per year in these cities, NO2 and CO concentrations have not increased due to effective control measures… Particulate pollution is still severe, and it is the major air pollution problem in the mega cities.”


Complete Reference:

Chan, C. K. and X. Yao (2008, January), Air pollution in mega cities in china, Atmospheric Environment 42 (1), 1-42, doi:10.1016/j.atmosenv.2007.09.003

4 comments:

Dominik Brunner said...

The sentence "NO2 and CO concentrations have not increased due to effective control measures" has caught my attention since satellite observations are telling a completely different story. E.g. Richter et al. (Nature, 2005) reported on a 50% increase in NO2 over industrialized regions in China between 1996 and 2005. Van der A et al. (JGR, 2006)even reported an incredible 20% increase per year for the city of Shanghai.

Pawan Gupta said...

Those lines were from the conclusion section of the paper. I am not sure how they get those numbers?

Harish Gadhavi said...

Thanks Dominik bringing this to our notice. Chan and Yao show NO2 trend in Figure 4 for Beijing, Figure 6 for Shanghai and Figure 7 for Pearl delta river. Data in the figures are from Beijing, Shanghai, Guangzhou and Shenzhen Environmental Bulletin. I suppose the data from ground-based observations are shown. Either decreasing or constant trend for NO2 between 1996 and 2005 is apparent in all the figures.

Richter et al. (Nature, 2005) and Van der A et al. (JGR, 2006) report trend using satellite data.

It is indeed interesting and important to know what is reason for such a big discrepancy between satellite and ground-based observations?

References:
1) see blog for Chen and Yao reference

2) Richter, A., J. P. Burrows, H. Nüß, C. Granier, and U. Niemeier. Increase in tropospheric nitrogen dioxide over china observed from space. Nature 437 (7055), 129-132.

3) van der A, R. J., D. H. M. U. Peters, H. Eskes, K. F. Boersma, M. Van Roozendael, I. De Smedt, and H. M. Kelder (2006), Detection of the trend and seasonal variation in tropospheric NO2 over China, J. Geophys. Res., 111, D12317, doi:10.1029/2005JD006594.

Harish Gadhavi said...

This article is the highest downloaded article of Atmospheric Environment for the period of Jan-Mar 2008.