China’s “green wall” would be the solution to desertification. Created a bigger problem

The largest reforestation project in the world inadvertently brought an unstoppable outbreak of allergies in China. Now the authorities are discussing between redoing what was achieved-or giving in to pollen.

More than four decades ago, China has undertaken one of the largest environmental feats in modern history: desertification that threatened vast regions of the north of the country.

To do so, he raised a huge wallnot stone, but of trees – with the aim of calming the sand storms and recovering land lost by erosion.

What began as an ambitious ecological experience became one of the largest reforestation campaigns in the world. And this “Great Green WallIt was able to contain the advance of deserts like Gobi or Taklamakan.

But also literally sowed a new problem: An unstoppable outbreak of allergiestells the.

Since 1978, the Chinese government has planted more than 66 billion trees In an extension of 4,500 km, which cover provinces such as the inner Mongolia, Gansu and Shaanxi.

This massive effort of reforestation, which cost thousands of millions of euros, successfully restored more than 150,000 km² of forest cover and significantly reduced deserting deserts such as Gobi and Taklamakan.

Os Environmental successes of the project are undeniable. Satellite images show vast green extensions where sterile dunes previously dominated the landscape.

Between 2008 and 2018, the Frequency of sand storms In Beijing it decreased 70%, and scientists estimate that planted forests absorbed 5% of China’s CO₂ industrial emissions between 1978 and 2017.

However, this green transformation brought an unexpected cost. Cities like Yulin in the province of Shaanxi and Hohhot in the inner Mongolia now record Severos seasonal outbreaks of allergies – which affect almost one in three inhabitants.

The guilty is the pollenparticularly Artemisiaa sturdy plant species chosen by its ability to resist extreme climates and stabilize sand dunes.

One from Xi’an Jiaotong University and the Yulin Forest Institute, published last month in the Journal of Hazardous Materialsconfirmed that the artemisia pollen contains five volatile compounds trigger severe allergic reactions through immune system recetors.

During the flowering times, in August and September, these microscopic particles become aerotransported, causing various symptoms-ranging from hay fever to bronchial asthma.

The impact on health is significant. While the Chinese national prevalence of allergic rhinitis is about 18 %, the areas inside the Great Green Wall belt show27 % in Yulin and 32% in Interior Mongolia.

Compared to the national average, residents living near the large green wall have almost double the likelihood of developing allergies respiratory.

Ma Boresident in Hohhot, is an example of this problem. What started as occasional sneezing and tearful eyes evolved into respiratory problems bass with episodes of asthma, which got worse significantly from 2018. Your experience reflects Thousands of similar cases across the region.

The problem extends beyond artemisia. Salgueiros and huts, chosen by rapid growth and resistance, produce massive amounts of pollen that is carried by the wind. In spring, their aments float like snow through the streets of Beijing, Creating an “explosive mix” in the air.

Local governments are now implementing emergency measures. Beijing invested 747 million euros to replace problematic trees by less allergenic species such as ginkgos and plums, and applies vegetable hormones to prevent the formation of buds in existing trees.

However, these efforts are expensive and slow.

The selection of species reflected the challenging conditions in northern China – Dry and hot summers, cold winters and arid terrain, which required resistant and rapid growth varieties capable of soil stabilization.

“First we had to get greenthen we could think of everything else, ”he admits Gu leiProfessor of Botany at the Normal University of the Capital, to.

This challenge is not unique in China. Globally, urbanization and climate change are prolong and intensify pollen timesNote a.

The alergic rinite now affects one in five people in most industrialized countries, with rates that reach Two out of five people In sensitive areas such as Japan. And although hay fever or allergic rhinitis is not new, they are now more persistent and last longer.

Creating longer and warmer spring that anticipate pollen seasons and multiply their intensity. Recent studies have concluded that The seasons of pollen intensified Over the past three decades, as the weather has warmed.

China is now continuing a more balanced approach, selecting appropriate species to the ecosystem with lower allergenic potential.

However, as Yin Jaexpert at the University Hospital of Medicine of Pekín, “Opólen can spread dozens to hundreds of kilometers with a Single Vento Rajada“Highlighting the complexity of addressing this unintentional consequence of environmental restoration.

The story of the Great Green Wall is an example of how sometimes we get dog, sometimes not having it: even a well-meaning ecological project can create unforeseen challenges that require adaptive-and sometimes sometimes solutions take a step back.

China and Japan are already doing so, having in recent years launched programs for lower the concentration of allergenic species in cities.

The Government of Japan plans replace 20% of the country’s artificial ceders For less allergenic trees, over the next 10 years – the slaughtering of about 70 thousand hectares per year.

This is a drastic solution, which has not yet been discussed in Europe; But if one day we start to see our governments below to bedtracks, don’t worry: paradoxically, It can be for your health.