Contribution of biogenic volatile organic compounds to tropospheric ozone formation in the Pearl River Delta region of China

The Pearl River Delta (PRD) of China-encompasses 0.41% of China's land area but accounts for about 9% of China's national GDP- has been a rapidly developing economic region since 1980s. Like many other megacities in the world, it suffers from serious air pollution problems, particularly ozone (O3) pollution. O3, produced from a series of chemical reactions in the presence of nitrogen oxides (NOX), volatile organic compounds (VOCs) and sunlight, is harmful to both human health and the environment. As a major precursor of tropospheric O3, VOCs originate from both anthropogenic and biogenic sources. Biogenic VOCs (BVOCs), primarily composed of isoprene and monoterpenes, are emitted naturally in substantial quantities from certain types of terrestrial vegetation. The atmospheric reactivities of most BVOCs are higher than those of many anthropogenic VOCs (AVOCs), and thus, they are believed to play an important role in the formation of tropospheric O3. In metropolitan cities, the potential of BVOCs to form O3 is amplified by high concentrations of NOx. Therefore, characterization of BVOCs is essential for understanding O3 chemistry in urban areas, and for the regional air quality modelling. The following book chapter will summarize the findings from various air quality studies conducted in the PRD region, and provide a comprehensive review of the contribution of BVOCs to O3 formation in a wide range of space and time. By thoroughly evaluating the implications of photochemical oxidation of BVOCs, more effective air quality regulations could be developed to control O3 pollution.