This photo taken on Aug 13, 2025 shows a navel orange orchard on the bank of the Yangtze River in Daba village of Fengjie county, Southwest China's Chongqing municipality. [Photo/Xinhua]

　　More than a decade ago, when President Xi Jinping joined deliberations with national lawmakers and political advisers during China's annual two sessions in 2014, he raised pointed questions about fine particulate matter, or PM2.5, for three consecutive days.

　　"Compared with Beijing, how is the level of PM2.5 in Shanghai?" Xi asked during a panel discussion with Shanghai deputies to the National People's Congress, China's top legislature, on March 5 that year, in a widely reported exchange with the municipality's ecology and environment bureau head.

　　At the time, images of smog-shrouded skylines in Beijing were making global headlines, turning China's air pollution into an international talking point, and making PM2.5 — airborne particles measuring 2.5 micrometers or less in diameter that can harm the lungs — part of everyday vocabulary.

　　Today, the term is far less frequently heard. Clearer skies across many Chinese cities have become increasingly common. According to the Ministry of Ecology and Environment, China's air quality reached its best level on record in 2025, with the average PM2.5 concentration dropping to 28 micrograms per cubic meter.

　　The change reflects not only targeted pollution-control campaigns, but also a deeper transformation in China's green development philosophy — one that has been repeatedly articulated by Xi at the annual meetings of the NPC and the National Committee of the Chinese People's Political Consultative Conference, China's top political advisory body.