The NATO ARW in Irkutsk was an excellent occasion for the coming together of Eastern and Western scientists who are involved in tropospheric science; the workshop has greatly contributed to the scientific and social understanding among the participants from the many different countries. Many new personal contacts were made which will help to strengthen future collaborations. In particular, the Lake Baikal area and the Limnological Institute offer splendid opportunities for environmental research which, in part, is already on going. For most participants it was the first time to see the impressive nature of the Lake Baikal region. Hopefully, there will be a chance for a follow-up event in Siberia where researchers from the East and West can again meet and engage in fruitful scientific dialogue. The book contains extended abstracts of the lectures and the poster presentations presented at the NATO ARW "Global Atmospheric Change and its Impact on Regional Air Quality" Irkutsk, Lake Baikal, Russian Federation, August 21-27, 2001. The ARW was composed of 22 oral presentations by key lecturers and 6 additional shorter oral presentations from participants. In a special poster session the 36 poster contributions were presented and discussed. Unfortunately not all contributors submitted extended abstracts, however, to compensate two contributions have been added from 2 participants who were originally invited but were unable to attend.