Abstract：
With the acceleration of air cleaning activities in China, air pollution has entered a new stage characterized by seasonal interplay and predominance of fine particulate matter (PM2.5) and ozone (O3) pollutants. However, the differing peak seasons of these two pollution preclude the use of a unified indicator for air pollution complex. Given that peroxyacetyl nitrate (PAN) originates from secondary formation and persists under low-temperature conditions for extended periods, it is vital to determine whether its concentration can be used as an indicator to represent air pollution, not only in summer but also in winter. Here, PAN observational data from 2018 to 2022 for Beijing were analyzed. The results showed that during photochemical pollution events in summer, secondary formation of PAN was intense and highly correlated with O3 (R = 0.8), while during PM2.5 pollution events in winter, when the lifetime of PAN is extended due to the low temperature, the PAN concentration was highly consistent with the PM2.5 concentration (R = 0.9). As a result, the PAN concentration essentially exhibited consistency with both the seasonal trends in the exceedance of air pollution (R = 0.6) and the air quality index (R = 0.8). When the daily average concentration exceeds 0.5 and 0.9 ppb, the PAN concentration can be used as a complementary indicator of the occurrence of primary and secondary standard pollution, respectively. This study demonstrated the unique role of PAN as an indicator of air pollution complex, highlighting the comprehensive ability for air quality characterization and reducing the burden of atmospheric environment management.
摘要：
随着中国空气净化活动的加速，空气污染已进入一个新阶段，其特征是季节性相互作用和细颗粒物（PM2.5）和臭氧（O3）污染物占主导地位。然而,这两种污染的高峰季节不同，因此无法使用统一的空气污染综合指标。鉴于过氧乙酰硝酸酯（PAN）起源于次级地层，并在低温条件下持续较长时间，确定其浓度是否可以用作代表空气污染的指标至关重要，不仅在夏天，而且在冬天。这里,对北京2018-2022年的PAN观测数据进行了分析。结果表明,在夏季光化学污染事件中,PAN的二次形成强烈，与O3高度相关(R=0.8)，而在冬季PM2.5污染事件期间，当PAN的寿命由于低温而延长时，PAN浓度与PM2.5浓度高度一致(R=0.9)。因此,PAN浓度基本上与空气污染超标（R=0.6）和空气质量指数（R=0.8）的季节性趋势一致。当日平均浓度超过0.5和0.9ppb时，PAN浓度可以作为一级和二级标准污染发生的补充指标，分别。这项研究证明了PAN作为空气污染复杂指标的独特作用，突出空气质量表征的综合能力，减轻大气环境管理的负担。
