The Environment Ministry is warning hay fever sufferers to expect more cedar and cypress pollen this spring than last year.
The annual wave of cedar pollen is expected to peak in early to mid-March in Tokyo, Nagoya and western Japan, and in early to mid-April in the Tohoku region, the ministry said Friday.
It also expects heavy pollen around 10 to 20 days before and after these peak times.
The cedar pollen will start to emerge around mid-February on the Pacific side west of the Kanto region, and spread north through late March, according to the ministry.
In general, the peak of the dispersion is expected to last longer than last year. Some areas in Kanto, Tohoku and the Tokai region could get up to seven times more pollen, it said.