According to the data provided by the Ministry of ecological environment, 339 prefecture level and above cities across the country have carried out total VOCs monitoring represented by non methane total hydrocarbons to analyze the concentration level of VOCs in each city. At present, 134 cities have carried out VOCs automatic monitoring in cities with excessive ozone. With the arrival of hot summer, ozone is becoming the primary air pollutant in some cities. According to the results of the national air quality forecast consultation in the first half of July released by the Ministry of ecological environment, affected by the rise of air temperature, moderate ozone pollution may occur in North China, North Central East China, Chengdu Plain, Sichuan Basin and Guanzhong region of Shaanxi in the first half of July. Ozone pollution refers to the photochemical reaction of volatile organic compounds (VOCs), nitrogen oxides, etc. under solar radiation, resulting in the excessive concentration of ozone near the ground. According to the "ambient air quality standard" issued by China, the maximum 8-hour average ozone concentration exceeds 160 micrograms per cubic meter, forming ozone pollution; If it exceeds 215 micrograms per cubic meter, it will reach moderate pollution. Jianghuohua, deputy director of the Department of ecological environment monitoring of the Ministry of ecological environment, said that ozone has become the main atmospheric pollutant in summer at this stage. Since 2013, China has included ozone in the normalization monitoring of air pollutants. Ozone pollution has entered a high incidence period Ozone is a light blue gas. When ozone pollution occurs, it is often blue sky and white clouds, which are difficult for people to detect, and even have the illusion of "the air is very fresh". According to the mechanism of ozone generation, in a year, ozone pollution generally increases from May, reaches a high point in July and August, and gradually decreases after entering autumn. The formation mechanism of ozone is relatively complex. In summer or noon, with the increase of solar radiation and temperature, photochemical reaction intensifies, and ozone pollution also intensifies. According to the 2021 Bulletin of China's ecological environment, in 2021, the number of days exceeding the standard with ozone as the primary pollutant in 339 cities at prefecture level and above accounted for 34.7% of the total number of days exceeding the standard, second only to 39.7% of fine particulate matter (PM2.5). In key areas such as Beijing Tianjin Hebei and its surrounding areas, the Yangtze River Delta and the Fen Wei plain, the number of days exceeding the standard with ozone as the primary pollutant accounted for 55.4%, 41.8% and 39.3% of the total number of days exceeding the standard, respectively. Liubingjiang, director of the Department of atmospheric environment of the Ministry of ecological environment, said that the root cause of ozone pollution in China in recent years is the excessive and concentrated emissions of VOCs and nitrogen oxides. It is reported that the sources of VOCs include emissions from fuel, gas and coal-burning processes, as well as emissions from various human activities such as vehicle exhaust, paint spraying in decoration, and vehicle refueling; Nitrogen oxides mainly come from the emissions of various fuels during the combustion process, including the exhaust gas from industrial boilers, motor vehicle exhaust, etc. Strengthen ozone monitoring According to experts, ozone pollution will cause serious damage to the ecosystem. During the photochemical reaction of ozone generation, a companion - peroxyacetyl nitrate (Pan) will be produced at the same time. Pan will directly cause plant leaf damage, making green leaves turn yellow or even wither, causing damage to plants and reducing crop yield and productivity of forest system. The harm of ozone pollution to human beings is mainly caused by respiratory diseases, and the most serious is asthma. Pan will also have side effects on the human body, such as stimulating eyes to weep, and will also increase the risk of skin cancer. The Ministry of ecological environment has clearly stated that the focus of China's air pollution prevention and control during the "14th five year plan" period is the coordinated control of fine particulate matter and ozone. The Ministry of ecological environment will comprehensively promote the emission reduction of VOCs and nitrogen oxides through industrial, energy, transportation and other structural adjustments, as well as the implementation of emission reduction projects. With the "share" of ozone in air pollution increasing, Jiang huohua said that the Ministry of ecological environment is strengthening ozone monitoring, promoting the construction of collaborative monitoring capacity of PM2.5 and ozone, strengthening the monitoring of VOCs, nitrogen oxides, etc., mastering their concentration level, main sources, generation mechanism, and supporting the collaborative governance of air pollution. According to the data provided by the Ministry of ecological environment, 339 prefecture level and above cities across the country have carried out total VOCs monitoring represented by non methane total hydrocarbons to analyze the concentration level of VOCs in each city. 244 cities have completed the construction of automatic monitoring stations and launched networking. Cities with excessive ozone and other cities with high VOCs emissions have carried out 57-117 kinds of VOCs component monitoring. At present, 134 cities have carried out VOCs automatic monitoring in cities with excessive ozone. In the vicinity of highways, ports, airports, and railway freight yards, nitrogen oxides will be mainly monitored. Jiang huohua said that the Ministry of ecological environment will also improve the deployment of monitoring networks and deepen the analysis of monitoring data to support the accurate, scientific and legal treatment of ozone pollution. (Xinhua News Agency)