Air pollution in the Arctic is transboundary by nature and its causes may be attributed to more than one state. An issue thus arises with regard to shared responsibility of multiple states for transboundary air pollution in the Arctic. Transboundary air pollution caused by multiple states clearly differs from traditional bilateral atmospheric pollution as typically shown in the Trail Smelter arbitration. Shared responsibility which is distinct from traditional independent state responsibility is increasingly at issue in international law and the regulation of transboundary air pollution in the Arctic provides an interesting insight into this subject. Thus this article will seek to examine legal issues concerning shared state responsibility for transboundary air pollution in the Arctic.