According to environmental authorities in the Beijing-Tianjin-Hebei region, the annual PM2.5 concentration decreased by over 60 percent from 2013 to 2022.

Beijing's average concentration of PM2.5 fell to 30 micrograms per cubic meter last year, which was 66.5 percent lower than in 2013, according to the Beijing Ecology and Environment Bureau.

In Hebei, the average density of PM2.5 dropped to 36.8 micrograms per cubic meter last year, down more than 60 percent from 2013, according to the province's Department of Ecology and Environment.

The province had just four days with heavy pollution last year, which was 69 days fewer than in 2013, and it had 270 days with good air quality, 121 more than in 2013.

Hebei's great improvement in air quality reflects ecological progress nationwide.

Since the 18th National Congress of the Communist Party of China in 2012, the country has firmly advanced the building of an ecological civilization, guided by the concept of "lucid waters and lush mountains are invaluable assets".

Thanks to the adoption of this concept, a once heavily polluted and deserted area in the city of Tangshan, Hebei, was transformed into a scenic area with clean water and green trees. The area has been a major provider of tourism income.

Tangshan, about 150 kilometers from Beijing, was once one of the major industrial cities in the country, with coal, steel and ceramics among its pillar industries. However, in recent years, local authorities have taken measures to improve the city's environment.

After years of management, the area that once suffered from coal exploitation has changed into the picturesque Nanhu Kailuan Scenic Area, which has served as the city's green "lung".

"The project has greatly improved the city's ecological environment and has thus become a top choice for citizens' leisure, fitness and sightseeing as well as tourism," said Guo Jinshen, deputy head of the ecological restoration department of the Hebei Department of Natural Resources.

According to Tangshan Culture and Tourism Group, which manages the scenic area, the site recorded more than 2 million visits last year, with annual revenue of more than 52.45 million yuan ($7.55 million).

The number had slumped due to disruptions of the COVID-19 epidemic, before which the scenic area saw about 7 million visits in 2019, according to the group.

"This is good work that proves the building of ecological civilization can bring out the best of economic development," Guo said.

Du Juan in Beijing contributed to this story.