Author: Bryan Chan
Air quality is worse in urban areas and in Asia due to the large population base and high urban density. Indeed, the air pollution challenge is huge in Asia because of the growing population size, and GDP per capita growth trend, especially in China and India with greater energy consumption and more pollutant emissions. 
Long term air quality trends were observed in 9 Asian cities – all are making progress in lowering the sulphur dioxide emissions and nitrogen oxides emissions modestly. However, PM levels are still high in many places and ozone levels have either gone up or remained flat.