The progress of the Cryptomeria japonica pollen front for 2017 (Fig 1) was monitored by tracking the first day of pollen release. A Durham sampler was used at 77 sites, and an IS-Rotary sampler at 8 sites distributed from Kyushu to Hokkaido. Results from the Durham sampler showed that, by early February, the pollen front had reached the western part of Chugoku and southern parts of Kanto and Tokai. By mid February, the front had moved up to the southern and northern areas of Kanto, Tokai and the southern area of Tohoku, the southern to central parts of Kinki, and the whole of Chugoku and Shikoku, with the exception of its southern region. By late February the front had moved up to the central area of Tohoku, central Chubu and the whole of Hokuriku and northern Kinki. By early March, the front was recorded in central to northern parts of Tohoku and, unexpectedly, to central Tokai. While by mid March the front had reached the northern part of Tohoku district. The front finally arrived in the eastern and middle parts of Hokkaido by early April.
