Every year, millions of Japanese celebrate the blossoming of delicate cherry trees, heralding the arrival of spring. But this change in seasons is accompanied by painful weeks of continuous sneezing, nasal congestion and watery eyes in a large percentage of the Japanese. Few people in the Asian country are aware that this public health problem has anything to do with World War II (1939-1945) or is an expected consequence of climate change.
affect spring sensitivity ( Hey Fever) commonly referred to as pollen allergy or hay fever affects different proportions of populations around the world. In the United Kingdom, at least one in four people suffer from it, according to UK National Health Service data, while the rate is less than 10 percent in the United States.
But this percentage in Japan is unprecedented, as a survey conducted by a group of Japanese multidisciplinary doctors in 2019 showed that about 40 percent of the country’s population of 123 million people suffer from some form of this health symptom known locally as “Kafuncho” (dust disease). pollen).
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In the spring, cedar trees release large amounts of pollen to form a cloud
The Japan Forest Agency has predicted that spring allergy disease will cause economic losses of at least $2.2 billion a year, which also includes health care bills and reduced worker productivity. And at the beginning of April / April Prime Minister Fumio Kishida declared this health condition a “social problem” and instructed his ministers to find a solution.
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What is the cause of spring allergy in Japan?
The pollen secreted by many plants causes allergic reactions. But in Japan, this health problem has to do with two types of trees: red cedar and cypress.
These trees are native to the country and have been part of their natural environment for hundreds of years, so why did they become a problem?
“During World War II, forests in Japan were cut down and destroyed,” Iwao Uehara, professor in the Department of Forestry at Tokyo Agricultural University, told the BBC. “Because of the scarcity of wood after the war, large numbers of red cedar and cypress trees were planted, because they grow relatively quickly.”
This feature made it ideal for meeting the country’s need for timber in the process of reconstruction according to David Weidman, a historian at the University of California, Irving who specializes in Japanese environmental history, which led to an increase in its cultivation.
“One of the most important needs of Japan immediately after the war was to obtain the necessary materials for the reconstruction of cities,” says Weidmann.
“It is important to mention here the campaign of aerial firebombing that destroyed traditional wooden buildings in Japan in the last months of World War II.”
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Pollen causes allergies even in animals
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The Allied occupation of Japan ended in 1952, but the cultivation of red rice and cypress continued to expand in the following years.
In some cases, natural forests have been cleared and replaced with red cedar and cypress, said Professor Uehara. “Today, Japanese red cedar makes up 45 percent of the planted forests in Japan, and cypress 25 percent.”
These two types of trees depend on wind pollination for reproduction, which means releasing abundant amounts of pollen into the air.
The economic importance of these trees declined in the following decades, due to the decline in the price of imported wood from the seventies of the last century.
Because of the lack of consumption of wood produced from these two types of trees in the country, the red cedar forests became denser and the trees larger, exacerbating the problem of pollen clouds.
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Scientists warn of the exacerbation of spring allergy symptoms as a result of the long period of pollen release and its quantities due to global warming
The Japanese Ministry of Agriculture estimates that red cedar forests alone cover 12% of the country.
But Professor Uehara explains that red cedar and cypress trees are not the only factor “responsible” for Japan’s spring allergy crisis. There are other factors that play a role in this crisis, such as air pollution in cities, where some pollutant particles combine with pollen, making them more allergenic.
And there’s also the climate change factor, as scientists say that warmer temperatures are causing trees around the world to produce more pollen, for longer periods of time, and at earlier dates than in previous years.
In a study published in March 2022, researchers from the University of Michigan found that the duration of the pollen production season in the United States and Canada increased by at least 20 percent between 1990 and 2018, and the concentration of pollen in the air increased by 21 percent. Far, according to the study authors, to global warming.
It was reported by the Japan Weather Association in April / Last April, the pollen outbreak in some regions of the country began two weeks earlier than usual in 2023 compared to last year.
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The annual economic cost of pollen allergy is estimated at $2.2 billion in Japan
Japanese media have speculated about measures the government might take to mitigate this crisis, from reducing red cedar forests to using artificial intelligence to track the release of pollen.
But Professor Uehara says the problem is deeper than that and holds an important lesson not only for Japan but for the whole world: the destruction of biodiversity can lead to unforeseen consequences decades later. “The main step that had to be taken was to expand the area of forests that includes many types of trees, not just one or two,” he said. .
2023-05-13 05:49:05
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