Author: Zhang Houmei (a grass-roots environmental protection cadre in Guangyuan City, Sichuan Province), on November 23, the Ministry of Ecology and Environment reported the national air quality in October 2022. This is the Ministry of Ecology and Environment, in accordance with the relevant requirements of the Three Year Action Plan for Winning the Battle of Blue Sky Defense issued by the State Council, on the basis of the original ranking of 74 key cities in terms of air quality, expanded the scope of the ranking cities to 168 prefecture level cities and above, and released the list of the top 20 cities with relatively good air quality and the last 20 cities with relatively poor air quality every month. From January to October this year, the air quality of Lhasa, Zhoushan, Fuzhou and other cities was good, and Ya'an City of Sichuan Province was also listed again, with the specific ranking of 15th. Since the 18th National Congress of the Communist Party of China, our Party has strengthened its overall leadership over the construction of ecological civilization, placed ecological civilization construction and environmental protection in a prominent position in the overall work, and made a series of major strategic arrangements. In the past decade, the blue sky and white clouds have re emerged, the green landscape has continued to expand, the green economy has accelerated development, energy and material consumption has continued to decrease, heavy smoke and haze have been effectively curbed, black and smelly water bodies have significantly decreased, urban and rural environments have become more livable, and solid steps have been taken to build a beautiful China. The blue sky defense war is the most important part of the in-depth fight against pollution. In recent years, with our unremitting efforts, the national ambient air quality has been continuously improved. However, due to the lagging transformation of regional industrial structure, energy structure, transportation structure and other factors, the results of air quality improvement have not been completely stable. As we all know, ozone in summer and PM2.5 in winter are two "roadblocks" on the road to improving air quality. In autumn and winter, the situation of air pollution prevention and control is becoming more severe due to adverse factors such as terrain, meteorology and poor pollutant diffusion conditions. As an important city in Sichuan Basin, Ya'an is evaluated as having good air quality this time, which is not easy. It also shows that the construction of ecological civilization has been a long-term success. The blue sky defense war is both a tough battle and a protracted war. At present, the prevention and control of air pollution has entered the deep-water area, and the governance and adjustment of industrial structure, energy structure and other issues are hard to chew. The concentration changes of PM2.5 and ozone are like a seesaw: once the particle concentration decreases, the ozone concentration rises instead. To this end, we should work hard day by day with a sense of urgency of "never letting go". We should stick to it for a long time. It is necessary to highlight the key points, comprehensively use economic, legal, scientific and administrative means, make full use of radar, laser and other scientific and technological means to accurately analyze and predict meteorological conditions and air quality change trends, closely focus on the treatment of regional characteristic pollutants, seize the key period of summer prevention, autumn and winter prevention, strictly control "industrial sources", "dust sources", "mobile sources" and "non-point sources" pollution, and fight the key battle of blue sky defense. The prevention and control of air pollution requires both "help from heaven" and "human effort". "Heaven helps" is gratifying; When "God doesn't help", we should give full play to people's initiative. When the weather is good, pollution should not be allowed; When the weather is bad, we should take the initiative to implement emergency management and control in a timely, decisive and accurate manner. If the peak shift production is limited, we should "serve penalties" to minimize pollution. Whether it is summer pipe or winter prevention, we should detail the