Aerial photo taken on May 25, 2019 shows the scenery of Baoji, northwest China's Shaanxi Province. Baoji has been promoting green development by strengthening environmental protection efforts such as afforestation and ecological rehabilitation to fight air and water pollution. (Xinhua/Tao Ming)

Staff members in charge of environment monitoring test the water quality of the Weihe River in Baoji, northwest China's Shaanxi Province, April 9, 2019. Baoji has been promoting green development by strengthening environmental protection efforts such as afforestation and ecological rehabilitation to fight air and water pollution. (Xinhua/Sun Hai)

Aerial photo taken on May 25, 2019 shows the Shigu Pavilion in Baoji, northwest China's Shaanxi Province. Baoji has been promoting green development by strengthening environmental protection efforts such as afforestation and ecological rehabilitation to fight air and water pollution. (Xinhua/Tao Ming)

Citizens walk on a suspension bridge transverse the Weihe River in Baoji, northwest China's Shaanxi Province, May 25, 2019. Baoji has been promoting green development by strengthening environmental protection efforts such as afforestation and ecological rehabilitation to fight air and water pollution. (Xinhua/Tao Ming)

Citizens walk in Weihe River Park in Baoji, northwest China's Shaanxi Province, May 25, 2019. Baoji has been promoting green development by strengthening environmental protection efforts such as afforestation and ecological rehabilitation to fight air and water pollution. (Xinhua/Tao Ming)

Aerial photo taken on May 22, 2019 shows the scenery of Baoji, northwest China's Shaanxi Province. Baoji has been promoting green development by strengthening environmental protection efforts such as afforestation and ecological rehabilitation to fight air and water pollution. (Xinhua/Tao Ming)

Aerial photo taken on May 22, 2019 shows the Shigu Pavilion in Baoji, northwest China's Shaanxi Province. Baoji has been promoting green development by strengthening environmental protection efforts such as afforestation and ecological rehabilitation to fight air and water pollution. (Xinhua/Tao Ming)

Aerial photo taken on May 22, 2019 shows the sunset scenery of Baoji, northwest China's Shaanxi Province. Baoji has been promoting green development by strengthening environmental protection efforts such as afforestation and ecological rehabilitation to fight air and water pollution. (Xinhua/Tao Ming)

Aerial photo taken on May 24, 2019 shows the scenery of the Weihe River in Baoji, northwest China's Shaanxi Province. Baoji has been promoting green development by strengthening environmental protection efforts such as afforestation and ecological rehabilitation to fight air and water pollution. (Xinhua/Tao Ming)

Photo taken on May 24, 2019 shows the Weihe River wetland in Baoji, northwest China's Shaanxi Province. Baoji has been promoting green development by strengthening environmental protection efforts such as afforestation and ecological rehabilitation to fight air and water pollution. (Xinhua/Tao Ming)

Aerial photo taken on May 22, 2019 shows the scenery of the Weihe River in Baoji, northwest China's Shaanxi Province. Baoji has been promoting green development by strengthening environmental protection efforts such as afforestation and ecological rehabilitation to fight air and water pollution. (Xinhua/Tao Ming)

Photo taken on May 24, 2019 shows the Weihe River plain in Baoji, northwest China's Shaanxi Province. Baoji has been promoting green development by strengthening environmental protection efforts such as afforestation and ecological rehabilitation to fight air and water pollution. (Xinhua/Tao Ming)