A drone photo shows a view of Yuehu park and city skyline of Ningbo City,kalyan milan matka east China's Zhejiang Province, Sept. 5, 2024. In recent years, the air quality in Zhejiang province has witnessed a steady improvement. According to statistics, the PM2.5 density, a key indicator of air pollution, in April, May, June, and July this year, was the best level compared with the same period of the previous years. (Xinhua/Huang Zongzhi)

A drone photo shows boats sailing in the Shenjiamen fishing port in Zhoushan City, east China's Zhejiang Province, Sept. 7, 2024. In recent years, the air quality in Zhejiang province has witnessed a steady improvement. According to statistics, the PM2.5 density, a key indicator of air pollution, in April, May, June, and July this year, was the best level compared with the same period of the previous years. (Photo by Zou Xunyong/Xinhua)

A drone photo shows a view of Lucheng District in Wenzhou City, east China's Zhejiang Province, Sept. 7, 2024. In recent years, the air quality in Zhejiang province has witnessed a steady improvement. According to statistics, the PM2.5 density, a key indicator of air pollution, in April, May, June, and July this year, was the best level compared with the same period of the previous years. (Photo by Liu Jili/Xinhua)

A drone photo shows the Baochu Tower near the West Lake in Hangzhou, east China's Zhejiang Province, Sept. 7, 2024. In recent years, the air quality in Zhejiang province has witnessed a steady improvement. According to statistics, the PM2.5 density, a key indicator of air pollution, in April, May, June, and July this year, was the best level compared with the same period of the previous years. (Xinhua/Xu Yu)

Visitors walk on the dike of the West Lake in Hangzhou, east China's Zhejiang Province, March 26, 2024. In recent years, the air quality in Zhejiang province has witnessed a steady improvement. According to statistics, the PM2.5 density, a key indicator of air pollution, in April, May, June, and July this year, was the best level compared with the same period of the previous years. (Xinhua/Huang Zongzhi)

A drone photo shows a view of the Grand Canal in Hangzhou, east China's Zhejiang Province, June 12, 2024. In recent years, the air quality in Zhejiang province has witnessed a steady improvement. According to statistics, the PM2.5 density, a key indicator of air pollution, in April, May, June, and July this year, was the best level compared with the same period of the previous years. (Xinhua/Weng Xinyang)

A drone photo shows visitors wearing traditional Chinese costume on a stone bridge in Hangzhou, east China's Zhejiang Province, June 12, 2024. In recent years, the air quality in Zhejiang province has witnessed a steady improvement. According to statistics, the PM2.5 density, a key indicator of air pollution, in April, May, June, and July this year, was the best level compared with the same period of the previous years. (Xinhua/Weng Xinyang)

A drone photo shows a view of Maoli Village in Jiangbei District of Ningbo City, east China's Zhejiang Province, July 23, 2024. In recent years, the air quality in Zhejiang province has witnessed a steady improvement. According to statistics, the PM2.5 density, a key indicator of air pollution, in April, May, June, and July this year, was the best level compared with the same period of the previous years. (Xinhua/Jiang Han)

Visitors watch the sunset scenery by the West Lake in Hangzhou, east China's Zhejiang Province, Aug. 9, 2024. In recent years, the air quality in Zhejiang province has witnessed a steady improvement. According to statistics, the PM2.5 density, a key indicator of air pollution, in April, May, June, and July this year, was the best level compared with the same period of the previous years. (Xinhua/Jiang Han)

A drone photo shows a view of a steel-themed park in Hangzhou, east China's Zhejiang Province, Aug. 29, 2024. In recent years, the air quality in Zhejiang province has witnessed a steady improvement. According to statistics, the PM2.5 density, a key indicator of air pollution, in April, May, June, and July this year, was the best level compared with the same period of the previous years. (Xinhua/Jiang Han)