GAW Report No. 205 - IGAC Project

CHAPTER 3 - ASIAAir pollution levelsAir pollution is a serious environmental problem in Asian megacities. Concentrations of airpollutants, especially particulate matter, are frequently higher than those of the WHO guidelines andthe ambient air quality standards of their own countries.Megacities in Asia have taken various measures to control air pollution; some measuresimplemented in developing megacities are equally strict as those in the developed ones. Forexample, in 2008, Beijing implemented vehicular emission standards on new cars equivalent toEURO-IV. Introducing lead-free gasoline in many developing megacities proved to be effective inreducing lead concentrations in particulate matter. Clean energy and advanced publictransportation systems have also played important roles in improving the air quality in Asianmegacities.Monitoring network data show that air pollution in Asian megacities remains a serious risk tohuman health and ecosystems. This indicates that all the air pollution mitigation efforts put forwardby megacities to date still have not gone far enough. With the fast social and economicaldevelopment and urbanization in Asia, new emission sources are being added to the old emissionsources that are currently not well controlled. How to realize the co-benefits of controlling airpollution and reducing climate change in Asian megacities requires systematic research efforts.3.2 BANGKOK, THAILANDIntroduction and specific features of the cityBangkok, the capital city of Thailand, is recognized as a megacity in South East Asia and isfacing serious air pollution problems. Bangkok and five bordering provinces including SamutPrakarn, Nonthaburi, Pathumthani, Nakorn Pathom, and Samut Sakorn are known collectively asthe Bangkok Metropolitan Region (BMR), which is an economic centre of Thailand. BMR has anarea of 7,762 km 2 and is situated in the central part of Thailand in the Chao Phraya River Basin.Bangkok city is located around 13°45’ Northern latitude and 100° 35’ longitudes in an immediateproximity to the Gulf of Thailand. BMR has a total population of about 10.1 million (as of 2007),which comprises around 16% of the total population in Thailand (63.0 million, as of 2007). In 2007,the population density in Bangkok was 3,644 persons per km 2 while the average population densityin BMR is 1,297 persons per km 2 [NSO, 2009]. Bangkok land use comprises 23.4% for residentialarea, 23.6% for agricultural area, 8.2% for road transportation, 3.9% for commercial area, 24.2%un-use land, and the rest are for other purposes [Department of City Planning, 2008].The Gross Domestic Product (GDP) of Thailand is continuously increasing. In 2008,Thailand GDP was 9,075 Billion Baht, a growth of around 6.4% from 2007, and the national incomewas 6,687 Billion Baht [BOT, 2010] (the exchange rate is around 35 Bath for 1 USD in 2007).Accordingly, the demand for electricity has increased. In 2008, a total of 148,200.93 Million kWhwas required across the country, 0.87% increase from 2007 [EGAT, 2008]. Electricity consumptionin BMR is also increasing, similar to the trends of electrical consumption in Thailand, especially inthe inner Bangkok area.BMR experiences the tropical monsoon climate with two distinct seasons. The wet seasonextends from mid-May to mid-October, when the southwest monsoon dominates and brings inwarm, moist air from the Gulf of Thailand and the Andaman Sea. The southwest monsoon and theInter Tropical Convergence Zone (ITCZ) cause heavy rainfall during the wet season. The dryseason can be further classified into two periods. The first period (mid-October to mid-February),known as the local winter, is characterized by mild weather under the influence of the northeastmonsoon that brings in cold, dry air associated with a high-pressure ridge extending from theanticyclone in China. The second period of the dry season (mid-February to mid-May) is known asthe local summer when weather is the hottest of the year, with the highest temperature occurring inApril [TMD, 2009]. Bangkok is also under the influence of a sea land breeze. The southerly seabreeze counteracts the northeasterly monsoon during the winter, which results in low windconditions over the city. This, in turn, reduces the mixing and enhances pollution build-up [Zhang63