Hay Fever in Japan: A Man-Made Nationwide Epidemic

Hay Fever in Japan: A Man-Made Nationwide Epidemic

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Hay fever
How did a condition once thought to be non-existent in Japan become the country's "national illness"? Blame the government, says Krys Suzuki.

Once upon a time, the forests of Japan were beautiful, natural expanses of a variety of trees, plants, and wildlife. Along with different types of cedars, maples, oaks, and other broadleaf trees grew side by side. It was a place of nature, beauty, and diversity.

And during this time, when the forest grew in this diverse, natural state, the people of Japan hardly knew of a thing called “hay-fever” (花粉症, kafunsho). So how has it come to a point where these allergies now run so rampant, it has been dubbed the “national illness,” or 国民病 (kokuminbyo), of Japan?

Cases of hay fever have been steadily increasing since the 1980s, and don’t show much sign of stopping, despite certain measures being taken to prevent its growth. Where it was once believed that hay fever was non-existent in Japan, it is now said to affect about a quarter of the population, compared to about 8% of adults in the United States.

Hay fever was first recorded in 1964 during the Tokyo Olympic Games, and named “Japanese cedar pollinosis” by Yozo Saito, an allergy specialist of Tokyo Medical University and the “father of hay fever,” in the same year. By the 1980s, the epidemic had gotten so bad that it was considered a social problem.


でもね、それは今は昔の物語。現代に生きる日本人の国民病は、春先に襲う百年の恋もさめる病気、スギ花粉症です。 なんで恋がさめるかって?だって、いったんスギ花粉症に襲われたら、くしゃみ・鼻みず・鼻づまりで、おまけに目のまわりのかゆさにかきむしり、まるでお岩さん状態。どんな美男美女でも、二目と見られない状況に陥ります。 せっかくの春に、恋を語るには最悪の病気なのです。 …

(JP) Link: How Did Hay Fever Begin?

What triggered this sudden increase in the hay fever plague in a nation once exempt from its wrath?

Where Have All The Forests Gone?

Japan suffered much damage, both economical and environmental, after the war. In order to recover on both fronts as quickly as possible, the government sought out new, aggressive industrial policies and environmental engineering strategies to restore both at the same time.


Enter the Japanese cedar tree, or cryptomeria japonica (杉, sugi), which was known to be the most economically beneficial tree in terms of growth and usability. It is a native tree to Japan, and also the prime culprit behind the national hay fever epidemic.

The government took it upon themselves to not only replant the damaged forests with these trees, but to also cut down and replace other more diverse forests with the same tree as well, regarding all other varieties of deciduous trees as slow-growing and “commercially useless.” What resulted 50 years later was a man-made expanse of Japanese cedars, now accounting for over 40% of Japan’s forests, which were no longer diverse, and therefore no longer supportive of the natural cycles of the ecosystem.

The purpose of this movement was to simultaneously restore damaged wooded areas and make Japan more self-sufficient in the lumber industry. In other words, Japanese cedars were being injected into the land in greater amounts than naturally observed as some sort of vaccination in an attempt to rebuild and restore the financial immunity of Japan.

However, as time passed, the repercussions of this complete disregard for the laws of nature have become increasingly obvious. The over-abundance of a single native tree has threatened the cycles of the ecosystem, the habitats of surrounding wildlife, and the ability of the land to absorb water. The result is soil erosion, and a greater occurrence of natural disaster, such as landslides.

And though the financial immune system of Japan may indeed have been boosted as a result for a short period of time, the immune system of its actual citizens suffered quite a blow.


スギを蹴飛ばし、舞い落ちる黄色い花粉に身を隠す。かつては全国各地で見られた遊びのひとこまだ。スギの雄花1つには数十万個の花粉が入っているといわれる …

(JP) Link: Cedar Trees, Hay Fever, and the People of Japan

Hay Fever: A National Epidemic

Hay fever is caused by the reaction of the human immune system to plant pollen, such as cedar and ragweed. Though now classified as the “national illness of Japan,” symptoms are not much different than in other countries – sneezing, runny nose, itchy eyes, etc.

However, what makes Japanese hay fever unique is not just the amount of people afflicted by it, but the severity of the symptoms. In fact, no other country is believed to experience hay fever to the same degree as Japan does. An observation by Dr. Saito puts into perspective just how relentless hay fever has actually become:

At the peak, you can actually see a pollen fog coming from the cedar forests… It’s so bad that when people first began to notice this a decade or so ago, they thought there were forest fires.

On the Japanese blog below, allergy sufferers gather to lament their symptoms.

花粉症大国の日本でいまだにスギが植林され続ける理由 – NAVER まとめ


(JP) Link: Another Painful Year For Allergy Sufferers

The allergy season in Japan typically begins in February and decreases towards the end of April, the season that cedar and cypress trees scatter pollen. And thanks to the government’s decision to overplant so many of the same tree 50 years ago, as well as replace already existing forests with unnatural, man-made cedar forests, there are now simply too many cedar trees throughout the country, producing and scattering pollen in unprecedented, never-before-seen amounts, amounts far greater than people’s bodies have evolved to handle.

In addition to the over-planting of trees, these man-made forests have been poorly maintained (if at all), causing the pollen spread to become even worse.

However, an interesting trend has taken hold. Despite the culprit behind the allergies being these densely growing cedar forests, symptoms have been noticed to be more severe in cities and urban areas rather than the actual forests, with some cities recording as many as 1 in 3 people suffering. There are several reasons why.

In 2014, a study revealed air pollution, especially diesel exhaust, tends to worsen allergy symptoms, and another 2012 study suspected that climate change also attributed heavily to pollen production, predicting that number to double by 2040.

Another factor is the environmental structure of urban versus natural areas. Pollen is typically absorbed by the ground when scattered in mountains and forests. However, in street-paved cities where natural ground is scarce and concrete is prevalent, these allergens don’t have the chance to be recycled back into nature, and are instead scattered and re-scattered every time the wind blows.

(JP) Link: Research Shows Increase In Severity and Length of Hay Fever Due to Climate Change

The Economic Cost Is Nothing to Sneeze At

A lack of forest diversity and pollution have meant disaster for Japan’s collective sinuses. (Picture: Rise / PIXTA(ピクスタ))

Allergy sufferers aren’t the only ones experiencing misfortune thanks to hay fever.

The planting of cedar forests as an initiative to improve the economy has exhausted its limits. While an abundance of cedar, the most cost-effective variety of wood, may have proved profitable back in the day, their necessity is dwindling, as cheaper imported timber becomes more and more available from places like Southeast Asia. This leaves Japan with an overstock of unsellable wood, contributing further to the poor maintenance of the forests and the overgrowth of these trees, which otherwise would have been chopped down and sold, offering more opportunities to replant them with less pollen-producing varieties as a regular part of the process.

The hay fever issue also costs the Japanese government money in more ways than a simple business loss. With symptoms as severe as they are in Japan, it often rises to the level of a cold or flu-like illness, causing people to miss work or even stay completely house-bound. Not only does this affect productivity and work performance, but it also lowers consumption, as fewer people shop or take trips.

「花粉の大量飛散」が景気に悪影響なワケ スーパーは伸びるが百貨店には打撃

「花粉の大量飛散」が日本経済に大きなダメージを与えそうだ。第一生命経済研究所の永濱利廣首席エコノミストは「花粉の大量飛散は1~3月の個人消費を約5691億円も押し下げる可能性がある」という。影響があるのは、どんな業種なのか――。 記録的猛暑で「2013年以来の大量飛散」か …

(JP) Link: Hay Fever And Adverse Effects On Economy

Another financial setback is that the government has now been forced to take costly measures to reduce the pollen count, an expense which could have been avoided with proper research and understanding of the long-term side effects of these hastily-planted cedar forests.

Those measures include not just maintenance of the already-existing forests, but the cutting down and replanting of these forests with newer, low-pollen varieties of trees, as well as the scientific research and experiments required to develop them. It is estimated to cost the government about $7 million a year to replace these trees alone (the government is allowed to replant about 60 hectares of forest per year), and that doesn’t take into consideration the money that goes into other areas of planning and production, nor the other financial losses mentioned above.

Another factor to consider is how time-consuming this entire process actually is. If Japan were to replace every man-made cedar forest with these newer, less pollen-producing varieties, it could take up to 200 years, adding up to billions more dollars. That’s an entire several generations of people who will still have to suffer through these monster allergies before the benefits of these new government strategies are realized, and any hope of relief can come about.


「少花粉スギ」「無花粉スギ」は23年前から開発が進められている 苗木が植えられた面積はわずか0.3%にとどまる 「現在、スギ人工林の多くが植栽から50年が過ぎて本格的に伐採・利用が可能な時期」 「少花粉スギ」「無花粉スギ」は23年前から開発 3月に入り、本格的に花粉症に悩まされる季節が到来した。 気象情報会社「ウェザーニューズ」は2月25日、37都府県で花粉の飛散が本格化していると発表。 …

(JP) Link: Why Replanting Measures of Less- and No-Pollen Cedars Have Not Progressed

Advances in Prevention and Treatment

In addition to the attempt to reduce the amount of pollen production, the government is working in several other areas related to the improvement of allergy prevention and treatment, including more research to discover the causes of hay fever, as well as more effective and accessible prevention and treatment methods.

At the moment, there is no real “cure” for hay fever, though significant progress has been made in the advancement of immunotherapy, an injection therapy that changes how the immune system reacts to allergens over the span of a couple of years. Though a tedious and time-consuming process, immunotherapy does offer some hope and shows promise of becoming the next best thing to an actual cure. However, there’s still much work to be done to make the treatment more accessible and less invasive.

For now, most people rely on typical self-care methods such as allergy medicines, home remedies, prevention and reduction methods (such as wearing a face mask), and for some, simply weathering the storm and coping with symptoms until the season comes to a close.

はじめに 〜花粉症の疫学と治療そしてセルフケア〜|厚生労働省

日本医科大学耳鼻咽喉科 大久保公裕 ○花粉症の疫学 …

(JP) Link: Epidemiology and Treatment of Hay Fever and Self-Care

Hope…For The Next Generation

A proper remedy could run into the trillions of dollars. Many would argue that it is simply “too late” to do anything immediately beneficial to reverse the economic and environmental damages caused by prematurely-established government policies.

But there’s cause for hope. Action is already being taken – and, though it may take a considerable amount of time and a substantially generous budget, research progresses. And while this generation (and possibly the next three to five) may have to grin and bear it under the protection of facial masks, Japan can live in the hope, through its coughs and sneezes and itchy eyes, that sometime in the future, its children’s children might not have to suffer as much.

Additional Sources

Cedar and Cypress Forest Data

Percentage of Natural vs. Artificial Forests by Prefecture (as of March 31, 2017)

Hay Fever Patient Fact-Finding Report

Hay Fever Patient Fact-Finding Report Summary

Planting Low-Pollen Trees

Breeds of Low-Pollen Trees

300 Varieties of Cedar Trees

Kafunsho Navi

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Krys Suzuki

Krys is a Japanese-fluent, English native speaker currently based in the US. A former Tokyo English teacher, Krys now works full time as a J-to-E translator, writer, and artist, with a focus on subjects related to Japanese language and culture. JLPT Level N1. Shares info about Japanese language, culture, and the JLPT on Twitter (SunDogGen).

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