Economic growth with industrialization, urbanization, and motorization and consequent changes in land use/cover have been observed in the recent decades in Asia. This economic development brings a better life to people in the region but also puts huge pressure on the environment. The management capacity for the environment in general and air quality in particular has not been developed at the same pace. Dirty fuels are still widely used in combustion devices with low energy efƒciency that release large quantities of air pollution. As a result, several cities in developing Asia are known to be among the world’s most polluted. Air pollutant levels in many large urban areas in Asia have been reported to exceed the WHO (World Health Organization) guidelines and the respective National Ambient Air Quality Standards (NAAQS). In particular, some of the highest levels of ambient particulate matter (PM) are found in big Asian cities (Hopke et al., 2008; Kim Oanh et al., 2006). For example, the annual average of PM2.5 (particles with the aerodynamic diameter below 2.5 μm) at some locations in downtown in Beijing is above 100 μg/m3 (Kim Oanh et al., 2006), which is well above the WHO guideline value of 10 μg/m3 (WHO, 2005). Evidence conƒrmed high levels of surface ozone observed in most Asian large cities (Lee et al., 2002; Permadi and Kim Oanh, 2008; Zhang and Kim Oanh, 2002, and references therein), which is linked to intensive precursor emissions coupled with favorable meteorology conditions, such as high temperature and strong sunshine, which are available in most parts of tropical Asia all year.