Overview of the Special Issue "PM_2.5 in Asia" for 2015 Asian aerosol conference

The Asian Aerosol Conference (AAC), held every two years, is the most prestigious conference for aerosol researchers in Asian region. The 9th AAC (AAC 2015) was held by Japan Association of Aerosol Science and Technology (JAAST) on behalf of Asian Aerosol Research Assembly (AARA) from June 24 to 27, 2015 at Kanazawa, Japan. A total of 520 participants from 14 countries presented 430 papers, including 4 plenary lectures, 16 keynote speeches, 125 oral and 285 poster papers in the conference. There were 270 Japanese participants and 250 participants from abroad in which China (with 87 participants), Korea (with 77 participants) and Taiwan (with 57 participants) contributed to the most attendees. Among the papers presented in the conference, ‘PM_2.5 symposium’, "atmospheric aerosols’ and ‘urban air quality’ sessions addressed many important issues related to PM_2.5 and ambient aerosols in East Asian countries. The features of this conference is the inaugural presentation of six AARA fellows, bestowal of two Asian Young Aerosol Scientist Awards, and a half day symposium "Analysis of Aerosol by Young Asian Researchers" which was a great opportunity for the networking of young aerosol researchers in Asian region.