“Low-carbon, warmth, love,” reads the sign on a large green metal bin, into which Beijing resident Zhao Xiao stuffs her unwanted, old clothes. “If some poor Chinese person really needs them, that would be great and would make me feel less guilty about throwing them away,” said the 35-year-old resident of Dongcheng District.

Zhao is right to worry about what happens to her charitable donation. There are clothing collection bins dotted all around China’s major cities, but few of the garments go to charity. Some are sold to developing countries, others are either burned or buried in landfills.

In a country that makes more than 5 billion T-shirts a year, there is a stigma to wearing old or second-hand clothes and millions of tons of garments are discarded every day. An aspirational middle class, combined with a boom in e-commerce, has turned China into the world’s biggest fashion market, overtaking the U.S. last year. Greater China accounts for a fifth of Japanese retail giant Uniqlo’s global revenue and the company’s sales in the region rose almost 27% in the 2017-2018 fiscal year to more than $4 billion. Most of China’s purchases are fast fashion – mass produced, cheap, short-lived garments.

The result: China throws away 26 million tons of clothes every year, less than 1% of which is reused or recycled, according to state news agency Xinhua.

The environmental cost of this waste is huge. The fashion industry accounts for around 10% of global carbon emissions, more than is produced by all flights and maritime shipping combined, according to the Ellen MacArthur Foundation. By one estimate, reusing 1 kilogram of clothing saves 3.6 kg of carbon dioxide, 6,000 liters of water, 0.3 kg of chemical fertilizers and 0.2 kg of insecticides, compared with making garments from virgin resources.

Part of the problem in China is that recycling clothing is unprofitable by law. Non-charitable sales of used apparel are banned for health and safety reasons. In China, used clothes are considered unhygienic, even unlucky. And Covid-19 has reinforced that bias.

Outside the fifth ring road on a recent Sunday morning in northeast Beijing, dozens of people are browsing the Roundabout Charity shop, which is holding a second-hand fair. They’re buying toys, books, home décor. Almost nobody is in the clothes section. In a city with 20 million people, Roundabout is one of the few charity shops that even sells used garments.

“It’s for a great cause, but even my family and friends don’t understand why I buy second-hand when I can afford international brands,” said 38-year-old Chen Wen, a local resident. “When people see second-hand clothes, they don’t think eco-friendly, they think poverty.”

China authorizes government-approved organizations to collect and sort donated clothes that are in “excellent condition,” Few do. The time and effort aren’t worth it in a nation where used clothes are unpopular even in relatively poor regions. “Sometimes too many just pile up” at collecting sites, China’s Ministry of Civil Affairs says. “It’s difficult to deal with.”

So high-quality garments that are collected are usually sold overseas. China’s exports of used clothing rose to 6.4% of the world total in 2015, from less than 1% in 2010, according to the latest data from the U.K.-based Textile Recycling Association.

Many go to Africa. Ten years ago the U.K. supplied a quarter of the used clothing shipped to Kenya. Now China is the biggest supplier, accounting for about 30%, while the U.K.’s share has dropped to 17%.

Some Chinese exporters rely on the collection bins in residential neighborhoods, but many now use e-commerce sites like Alipay to solicit donations.

About 70% of the clothes collected by Hangzhou-based Baijingyu, or White Whales, are sold in overseas second-hand clothing markets, while 15% are down-cycled for use in construction, agriculture, or gardening, or sent to waste-to-energy incinerators, said Chief Executive Officer Jason Fang. With its main markets in Southeast Asia and Africa, most of its exports are summer apparel. Only about 15% of donations are given to poor regions in China.

“People want all their clothes donated to poor Chinese families, but it’s not very realistic anymore,” Fang said. A few years ago, if a jacket was 70% new, people would take it, but today I am too embarrassed to even show a jacket to a family unless it’s 90% new.”

Some of the clothes are shipped to Europe and the U.S first before being re-shipped to Africa for a better price, said Fang. “Every African client wants American clothes.”

Not long ago, China was a major importer. In small towns in coastal provinces like Fujian and Guangdong, sorting and selling used clothes from shipping containers of “foreign waste” used to be big business. But in 2017 China banned the import of 24 kinds of solid wastes, including textile products, forcing shippers to look for other destinations in Asia, or to recycle more waste at source.

“This is highlighting what is happening to the global markets as a whole,” said Alan Wheeler, general delegate of the textiles division at the Bureau of International Recycling. “Markets are becoming increasingly crowded. From an environmental point of view, the fact that Chinese people are sending more clothing for re-use and recycling is a good thing, but it also presents a real issue.”

One ray of hope is a small, but growing number of startups looking for novel ways to reuse old clothing. Re-Clothing Bank employs migrant women in a village near Beijing to cut up old clothes and make them into patchwork jackets, bags and carpets. “A middle aged security guard in Shanghai spent half his monthly salary to buy a coat I made from old clothes,” said Zhang Na, the startup’s founder. “That was when I thought there is a future in this.”

But the vast majority of China’s discarded apparel goes straight into the trash, exacerbating one of the country’s biggest environmental headaches. Most of the nation’s 654 giant landfills filled up ahead of schedule. The nation’s biggest dump in Jiangcungou, Shaanxi province, is the size of 100 football fields, but filled up 25 years earlier than designed after receiving almost four times the amount of daily waste predicted. As a result, China dumped more than 200 million cubic meters of waste into its coastal waters in 2018, according to the environmental ministry.

That’s promoted perhaps the fastest-growing solution for China’s unwanted garment problem: burn them. Cut and shredded pieces of cloth are added to wet waste in trash-to-energy incinerators to make them more efficient. China considers such plants a form of renewable power, despite the emissions they produce, and has tried to double their capacity in the past five years.

That’s not an environmentally sustainable solution, said Wheeler at the Recycling Bureau. “Clothing needs to be designed for durability and recycling and when people have finished with it, they need to send it for re-use.”

Wheeler said the real solution, though, is much simpler. “We need to buy less clothing.”