Staff at the Temple of Heaven in Beijing spray water on trees to decrease the pollen concentration on March 23, 2025. Photo: IC

Waves of yellow pollen swirled through the air as Chinese juniper trees at the Temple of Heaven in Beijing unleashed large amounts of pollen in recent days. Videos of the spectacle also went viral on China's X-like platform, Sina Weibo, sparking concern among allergy sufferers.

As temperatures rise, pollen levels in Beijing have surged. Meteorological data shows that this year's spring pollen peak arrived four to seven days earlier than in 2024 and is expected to last for another four weeks, according to the state broadcaster CCTV.

In response, many allergy-prone individuals have taken protective measures, donning face masks and goggles to minimize exposure.

According to Zhang Zhixiang, a professor at Beijing Forestry University, the widespread planting of Cupressaceae trees, especially Chinese juniper, is the main source of tree pollen in Beijing these days. But the planting is rooted in both historical and urban planning factors.

A complex issue

Beijing has two major pollen peaks each year. The first, from late March to late April, is dominated by pollen from Cupressaceae trees. The second, from late August to late September, comes from herbaceous plants, Zhang remarked.

The cyclical nature of Chinese juniper pollen follows a pattern known as the "mast year" phenomenon, where certain trees produce significantly more pollen in some years than others. 

"This year is a mast year, meaning a higher pollen output than usual," Zhang said. Weather conditions also play a crucial role - warmer temperatures accelerate pollen production, while strong winds aid in dispersal.

"Chinese juniper is a dioecious species, meaning only the male trees produce pollen, which is a key allergen," he said. "Additionally, the belief that poplar catkins cause allergies is a common misconception."

Chinese juniper trees, known for their longevity and symbolic significance, were historically favored by royalty and nobles. 

Many of these trees in the Temple of Heaven, for instance, are centuries old.

Additionally, Chinese juniper trees are a staple of Beijing's urban greenery due to their resilience and evergreen nature. 

Zhang Bo, deputy director of the Science and Technology Division of the Beijing Municipal Forestry and Parks Bureau, explained that in the early years of the founding of the People's Republic of China, Beijing's forest coverage rate was only 1.3 percent. 

According to Zhang, since the year 2000, it has become quite rare to see large expanses of forest plantations. The ones that exist today are mostly remnants from the past, decades ago. Back then, it was a phase of rapid greening, when people planted those that were cheap, easy to grow, and had a high survival rate.

By the end of 2024, Beijing's forest coverage rate has reached 44.95 percent, which is the result of years of greening efforts.

"Relatively dry and lacking water, the natural geographical characteristics of Beijing have largely determined the current structure of its greenery and landscaping," said Zhang Bo. 

Professor Zhang told the Global Times that completely replacing the existing Chinese juniper trees would be a massive, complex, and costly task. 

Moreover, pollen from various sources triggers allergies, making it impossible to eliminate all of them.

However, to combat the allergies caused by pollen, the Beijing Municipal Forestry and Parks Bureau has been making efforts in recent years, Zhang said.

Efforts underway

During the peak pollen season, urban parks and main forested areas have implemented measures in conjunction with regular landscaping maintenance, including trimming flower branches, spraying water, and wetting the ground, to reduce the amount of pollen dispersed, primarily from Chinese juniper trees. Additionally, pollen that falls onto the ground after wetting will be promptly cleaned up to lower the pollen concentration, introduced Zhang. 

The bureau has also teamed up with meteorological departments and local hospitals to form an expert team to carry out a series of studies, assessing the risk of pollen-induced allergies. Besides developing rapid diagnostic methods, they have also been working together to establish monitoring systems and release pollen forecasts.

Additionally, the bureau has strictly controlled the planting of high-pollen tree species, opting for lower-pollen alternatives. When planting Chinese juniper trees, authorities prioritize female trees, which do not produce pollen.

"I believe this kind of research will be a long-term endeavor. In the past, allergies may not have received much public attention, although we've been working on related issues. However, the resources, both in terms of personnel and funding, have been limited. Moving forward, we hope to actively seek more targeted support to expand our efforts," he noted. 

Qin He, associate chief physician at the Department of Otolaryngology, Head, and Neck Surgery at the Beijing Tsinghua Changgung Hospital, noted that in the last week, there has been a noticeable increase in patients seeking treatment for pollen allergies, reported Life Times on Friday.

Qin pointed out that allergy sufferers should pay attention to the pollen index and reduce outdoor activities when the index is high. 

Proper protection such as masks, hats, and protective glasses is important. Applying cream to exposed skin to act as a barrier can also be helpful. 

Allergy sufferers can also use a "pollen barrier agent" by spraying it on the nasal mucosa before going out. "When return home, clean your nasal passages  and other exposed skin, and change into clean clothes. Follow medical advice when taking medication," added Qin.