While some people might find garbage classification - it was made mandatory in Shanghai in 2019 - troublesome, the regulation has won the support of at least one foreigner who has been championing such efforts for the past decade.

"Waste recycling for the residents - this is an extremely complicated subject. I must tell you that it is absolutely an incredible achievement of Shanghai," says Marie Harder, a professor in the Environmental Science and Engineering Department of Fudan University.

In fact, the Briton had 10 years ago led a group of students to pick up rubbish in Shanghai neighborhoods.

Marie made the remarks in the "Shanghai Through Our Eyes" series that was produced by Xinmin Evening News to commemorate the 100th anniversary of the founding of the Communist Party of China this year.

The Information Office of the Shanghai Municipal People's Government launched the series on April 8.

"No city in the world has achieved the waste diversion that Shanghai has achieved. This is unbelievable, this achievement is already world-leading," she adds.

Jin Xinyi contributed to this story.