The Beijing authorities have vowed to take action on the floating fluffy tree seeds that irritate capital residents every spring, ending the problem by 2020.
Although freed from serious winter smog with the advent of spring, many Beijing residents are still wearing masks to prevent the seeds, known as catkins, from getting into their noses and mouths.
"They are annoying, they make me sneeze all day," a Beijing resident surnamed Zhao told the Global Times.
"Although I am not allergic to catkins, I feel itchy and uncomfortable when they fly into my face. And I am afraid that I will breathe them in," a female student at Peking University told the Global Times on Thursday.
Beijing has about 2 million female poplar and willow trees which produce catkins to spread their seeds every spring, the Beijing Municipal Bureau of Landscape and Forestry (BMBLF) was quoted as saying on Wednesday by the Beijing Morning Post.
Catkins can cause ailments including allergic responses and conjunctivitis. They are also very flammable, Gao Chengda, a forestry expert at the Chinese Academy of Forestry, told the Global Times.
An elderly man surnamed Zhao suffered second-degree burns to 18 percent of his skin in May 2016 in East China's Anhui Province after he set fire to catkins gathered in front of his house, Jiangsu TV reported at the time.
The bureau said on its website Wednesday that it will stop 400,000 trees from producing catkins this year, through various measures including replacing some trees and changing the sex of others. Male trees do not produce catkins.
The bureau said it will register and locate all the female poplar and willow trees within the Fifth Ring Road this year and replace them with male trees, to attack the catkins problem at root.
The bureau vowed to reduce the catkin level to a point that it does not "cause disaster" by 2020.
"We rely mainly on replacing most of the trees and cutting branches that produce catkins to manage the problem," said Li Junsheng, deputy director of the Research Center for Eco-Environmental Science at the Chinese Research Academy of Environmental Sciences.
"And besides poplar and willow trees, other species should be planted to safeguard biodiversity," Li said.
Shrinking green space
Due to the early onset of spring this year, Beijing was beset with flying catkins a few weeks earlier than usual, according to the Beijing Morning Post.
Zhao noted that there seem to have been more and more catkins in recent years.
Trees planted about ten years ago have gradually entered the mature stage, producing more catkins, Li explained.
The capital's loss of green spaces has worsened the situation, as the plants that grow in these areas were once able to trap the catkins, the BMBLF said at the press conference.
The bureau will increase the amount of green space in Beijing by 600 hectares in 2017, according to its official website.
Almost 120,000 female willows and poplars in Beijing will be injected with chemicals to stop them from making catkins, The Beijing Youth Daily reported on April 10, citing Che Shaochen, director of the BMBLF's Botany Conservation Office.
"I hope they will take action in advance, not wait to act until catkins have become a disaster," Zhao said, adding that cutting down trees that produce catkins would be a waste of resources.
The BMBLF said that they will not cut down female poplar and willow trees but will instead change their sex. They have also bred 300,000 male trees which will be planted in the next two years.
Poplars and willows, especially Chinese white poplars, are suited to North China as they do not require a lot of water and can help reduce air pollution, Gao said.
"We need trees for greening the city, meanwhile, we have to accept their disadvantages," Gao noted.
Every year, a poplar tree can absorb 172 kilograms of carbon dioxide, release 125 kilograms of oxygen and prevent the erosion of 16 kilograms of soil, the Beijing Morning Post said.
One mature willow tree can absorb 281 kilograms of carbon dioxide, releases 204 kilograms of oxygen and save 36 kilograms of soil.
Beijing started to plant the trees in the 1950s to make the city greener, the Beijing Morning Post reported.
It first imported trees from Germany and Italy, many of which were felled in 1995 because of long-running issues with insects.
"Imported trees might not fit the local environment and it costs a lot to maintain them," Li pointed out.
Many of the trees now producing catkins are Chinese white poplars planted in the late 1970s that were imported from neighboring Hebei Province, said the Beijing Morning Post.