Officials of different levels patrolled the streets, grasslands or along rivers, each wearing a red armband, and collecting trash whenever and wherever they encountered it, and they encouraged fellow citizen to start caring for the environment, Zhao Norjinma says.

As more people joined in the campaign, with strict supervision, over three years Gannan changed greatly, and an advertising campaign told the world about how it had been transformed.

In 2018 Zhao Norjinma received many tourists, perhaps keen to see how accurate the advertising was.

"They heard that Gannan had achieved its goal of no trash in sight, and they probably did not believe it so came to have a look for themselves," Zhao Norjinma says.

"They asked how it could be, wanting to know how many cleaners we had recruited, how many trash trucks we had bought and how frequently trash was collected. The thing is, it just wasn't like that. What happened was that everyone in Gannan had become a cleaner."

Last year the Gannan government decided to build guesthouses for the development of green tourism, and Zhao Norjinma's guesthouse was chosen as one of the models.