Pollen Allergy...A ManMade Plague

Amid the pink petalled cherry blossoms this week one can see people wearing all manner of masks and googles such as the Hello Kitty ones above to protect themselves against hay fever or kafunsho.
Simply defined kafunsho is the allergic reaction to airborne pollen most notably sugi(cedar) and hinoki(cypress) pollen which is prevalent at this time of year.
After World War 2 some seven million hectares of cedar and cypress was planted to provide timber for rebuilding.According to Alex Kerr in his book"Dogs and Demons The Fall of Modern Japan".."by 1997 Japan had replanted 43% of all its woodland with a monoculture of coniferous trees,mostly sugi,or Japanese cedar"pg 53.
An article in The Japan Times last week quoted a Forest Agency figure of "Almost a fifth of Japans land mass is planted with cedar and cypress trees."The Japan Times Saturday April 5th 2008 p 3.
It is these trees which produce the main source of pollen allergy rather than the traditional native broadleaf mix of maple,cherry and pine trees together with bamboo and grasses.

The 2001 edition of Kerrs book states that "Allergy to sugi pollen,an ailment almost unknown a few decades ago,now affects 10% of all Japanese"(page 53).
It appears that the percentage of the population annually affected however is increasing if the figures in The Japan Times are to be believed."...the allergens that affect as many as 20 million Japanese in March and April,or 16% of the population"and later in the same article "Almost 30% of Tokyo's population had symptoms of pollen allergies in 2006,up from 20% a decade earlier" The Japan Times Saturday April 5 2008 page 3.
One possible reason for this increase in the number of people affected is climatic.With warmer,longer summers providing favourable flowering conditions pollen levels increase the following season.
Other possible reasons include an aging population and rural depopulation which means that there are fewer local people able to prune,maintain and log these areas.Plus one must factor in the reduced Forest Agency workforce 7,000 in 2001 according to Kerr."Dogs and Demons"pg 54.
Nor should one forget that since World War 2 Japans dependence on cheaper imported timber has increased making the local product uneconomic to manage.
As for the trees themselves,planted after the War,most would be mature enough to produce pollen.And in the case of the long lived sugi,capable of releasing pollen for 300 or more years.
Locally in Nagoya and the surrounding region cedar pollen makes its presence felt from mid February to early April while hinoki or cypress pollen makes its appearance from early April to mid May.
The amount of pollen varies both on an annual and daily basis according to the weather.Judging from the nightly TV pollen forecast during the pollen season,days that are clear,warm and have variable winds are the worst ones for allergy sufferers.

Saturdays Japan Times article also notes that some 183 billion yen could be lost in April and May as sufferers stay home and reduce their spending.Nothing is stated as to whether cedar or cypress forests are being decreased or whether any non allergic strains are being developed as measures against the ailment.