Emission trends and mitigation options for air pollutants in East Asia

Abstract. Emissions of air pollutants in East Asia play an important role in the regional and global atmospheric environment. In this study we evaluated the recent emission trends of sulfur dioxide (SO₂), nitrogen oxides (NO_x), particulate matter (PM), and non-methane volatile organic compounds (NMVOC) in East Asia, and projected their future emissions up until 2030 with six emission scenarios. The results will provide future emission projections for the modeling community of the model inter-comparison program for Asia (MICS-Asia). During 2005–2010, the emissions of SO₂ and PM_2.5 in East Asia decreased by 15 and 12%, respectively, mainly attributable to the large-scale deployment of flue gas desulfurization (FGD) at China's power plants, and the promotion of highly efficient PM removal technologies in China's power plants and cement industry. During this period, the emissions of NO_x and NMVOC increased by 25 and 15%, driven by rapid increase in the emissions from China due to inadequate control strategies. In contrast, the NO_x and NMVOC emissions in East Asia except China decreased by 13–17%, mainly due to the implementation of stringent vehicle emission standards in Japan and South Korea. Under current regulations and current levels of implementation, NO_x, SO₂, and NMVOC emissions in East Asia are projected to increase by about one-quarter over 2010 levels by 2030, while PM_2.5 emissions are expected to decrease by 7%. Assuming enforcement of new energy-saving policies, emissions of NO_x, SO₂, PM_2.5 and NMVOC in East Asia are expected to decrease by 28, 36, 28, and 15%, respectively, compared with the baseline case. The implementation of "progressive" end-of-pipe control measures would lead to another one-third reduction of the baseline emissions of NO_x, and about one-quarter reduction of SO₂, PM_2.5, and NMVOC. Assuming the full application of technically feasible energy-saving policies and end-of-pipe control technologies, the emissions of NO_x, SO₂, and PM_2.5 in East Asia would account for only about one-quarter, and NMVOC for one-third, of the levels of the baseline projection. Compared with previous projections, this study projects larger reductions in NO_x and SO₂ emissions by considering aggressive governmental plans and standards scheduled to be implemented in the next decade, and quantifies the significant effects of detailed progressive control measures on NMVOC emissions up until 2030.