Hay fever in Japan
pollen from acres of Cryptomeria japonica
Hay fever in Japan (花粉症, kafunshō; "pollen illness") is most commonly caused by pollen from Cryptomeria japonica (known as sugi in Japanese and often translated as "cedar" though it is not a member of the Cedrus genus) and Japanese cypress (known as hinoki), two native Japanese tree species.
According to the Ministry of the Environment, as of 2019, 42.5% of Japanese suffer from some form of hay fever, and 38.8% suffer from cedar pollinosis.
Cause
Hay fever was relatively uncommon in Japan until the early 1960s. Shortly after World War II, reforestation policies resulted in large forests of cryptomeria and Japanese cypress trees, which were an important resource for the construction industry. As these trees matured, they started to produce large amounts of pollen. Peak production of pollen occurs in trees of 30 years and older. As the Japanese economy developed in the 1970s and 1980s, cheaper imported building materials decreased the demand for cryptomeria and Japanese cypress materials. This resulted in increasing forest density and aging trees, further contributing to pollen production and thus, hay fever. In 1970, about 50% of cryptomeria were more than 10 years old, and just 25% were more than 20 years old. By 2000, almost 85% of cryptomeria were over 20 years old, and more than 60% of trees were over 30 years old.
“Hay fever in Japan” enters the record as pollen from acres of Cryptomeria japonica. Crown Archives preserves that source wording while asking what fever, Japan and pollen can confirm, complicate or overturn.
Why this record matters
“Hay fever in Japan” is worth following because a concise public description often conceals a longer documentary argument. Here, fever, Japan and pollen provides the most credible route into that argument.
The citation trail is more important than the brevity of the summary: it shows where individual claims can be examined in context. The source revision retrieved here is dated Mar 23, 2026. The linked authority identifier is Q15662673. None of the 0 selected statements returned an explicit reference. The first chronological checks are 2019, 1970 and 2000.
Overview language is designed for orientation and should not be treated as a substitute for the evidence cited beneath it. The lead is largely declarative, so disagreement and counter-evidence require a deliberate search beyond the opening account. Authority statements aid reconciliation but still require their own references, qualifiers and ranks to be checked.
How to read it
Use the entry as an orientation point, then follow its citations and revision history. Names, dates and institutional relationships should be checked against the original record.
- Subject orientation
- Search vocabulary
- Locating named sources
The closest primary source, responsible institution and strongest cited specialist reference.
Three-step research path
- Establish the record: confirm the title “Hay fever in Japan”, its source revision and the description used here.
- Expand the search: follow Hay fever in Japan primary sources, Hay fever in Japan archive and fever research across catalogues and specialist indexes.
- Test the account: compare the strongest cited source with the responsible institution’s current record and note any disagreement.
Questions for further research
- Which source most directly establishes the central claim about “Hay fever in Japan”?
- Which cited source is closest to the event, object or claim?
- Which institution is responsible for the underlying evidence?
Search terms from this dossier
This entry incorporates text from “Hay fever in Japan” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.