The progress of the Cryptomeria japonica pollen front in 2007 was monitored by tracking the first day of pollen release using a Durham sampler at 98 sites, and an IS-Rotary sampler at 16 sites, distributed from Kyushu to Hokkaido. With the Durham sampler, from late January to early February, the pollen front was first found to occur both in the Tokai and in the southern Kanto districts facing the Pacific Ocean. During early to mid February the front reached the Kyushu, Chugoku, Shikoku, Kinki and Hokuriku districts, facing the Japan Sea, and also the northern parts of the Kanto area in central Honshu. By mid February the front was observed in the northern area of Chubu, facing the Japan Sea, and also in the central part of Tohoku; following this it reached northern Tohoku from late February to late March. The front finally arrived in the western part of Hokkaido from late March to mid April.
