# Scientific Analysis of Regional Air Pollution and Promotion of Air Pollution Management in East Asia Considering Co-benefits

Principle Investigator: Hajime AKIMOTO

Institution: Asia Center for Air Pollution Research (ACAP)

1182 Sowa, Nishi-ku, Niigata-shi, Niigata 959-2144, Japan

Tel: +81-25-263-0551 / Fax: +81-25-263-0556

E-mail: akimoto@acap.asia

Cooperated by: Japan Agency for Marine-Earth Science and Technology (JAMSTEC), National Institute for Environmental Studies (NIES), and Kanazawa University

## [Abstract]

Key Words: Transboundary air pollution, Asian air pollution, $ PM_{2.5} $ , Ozone, Black Carbon, Short-lived climate pollutants (SLCP), Emission inventory, Co-benefit approach, regional cooperation framework, Asia Science Panel for Air and Climate (ASPAC)

In order to cope with transboundary air pollution issues of $ PM_{2.5} $ and ozone ( $ O_{3} $ ) in Japan, this project targets to fill the gaps of the interface between science and national/international policy on atmospheric environment. Robust quantitative source-receptor relationships for $ PM_{2.5} $ and $ O_{3} $ were obtained through scientific studies integrating field observation, modeling, and emission inventories. Meanwhile, international framework of regional cooperation on atmospheric management in East Asia was analyzed in terms of political and policy science. Based on the review of existing air pollution-related initiatives, the research identified major factors to be included in the cooperative regional framework and their possible options. Lack of epistemic community among scientists, and scientists-policy makers interface was identified as a deficit in East Asia. In order to effectively promote regional cooperation, Asia Science Panel for Air and Climate (ASPAC) was proposed.

Springtime ozone over Japan was contributed from various source regions; 12% from China, 22% from Japan, and 7% from Europe/North America. $ PM_{2.5} $ over western Japan was contributed from China by $ >50\% $ , while that in Kanto region was most contributed by domestic emission. Typically 30% and 20% reduction in anthropogenic emissions of precursors from Japan/China/Korea and China/Korea would effectively reduce number of days with elevated concentrations over Japan for $ O_{3} $ and $ PM_{2.5} $ , respectively. Preliminary results suggested that emission reduction in the power and industry sectors in China would effectively reduce ozone and $ PM_{2.5} $ over Japan and China.

Regional Emission Inventory in Asia was updated as version 2 (REAS v.2) for 2000-2008 with higher spatial (0.25 degree) and temporal (monthly) resolution than in version 1, and the covered area has been expanded to include Asian part of Russia and Central Asia in addition to South, Southeast and Northeast Asia. The REAS v.2 was validated by a top-down approach using an inverse modeling technique with satellite observation especially for $ NO_{x} $ emissions in China.

In order to reduce emissions of air pollutants in East Asia, effectiveness of SLCP (Short-lived Climate Pollutants) co-benefits approach has been studied. The research clarified the importance of air pollution mitigation in Asia, which has much higher incentive than climate control. For $ O_{3} $ reduction as an SLCP, the importance of $ NO_{x}/VOC $ control was discussed as compared to the preferential methane control in the European and North American view. It was revealed that in order to prevent ozone pollution near the ground level $ NO_{x}/VOC $ reduction is much more effective, while methane reduction is more effective to reduce radiative forcing. Simultaneous reduction of both $ NO_{x}/VOC $ and methane is therefore recommended in East Asia.