Abstract Particulate matter (PM), especially those with an aerodynamic particle size of less than 10 μm (PM10), is typically emitted from transboundary forest fires. A large-scale forest fire may contribute to a haze condition known as a high particulate event (HPE), which has affected Southeast Asia, particularly Peninsular Malaysia, for a long time. Such event can alter the photochemical reactions of secondary pollutants. This work investigates the influence of PM on ground-level ozone (O3) formation during HPE. Five continuous air quality monitoring stations from different site categories (i.e., industrial, urban and background) located across Peninsular Malaysia were selected in this study during the HPEs in 2013 and 2014. Result clearly indicated that O3 concentrations were significantly higher during HPE than during non-HPE in all the sites. The O3 diurnal variation in each site exhibited a similar pattern, whereas the magnitudes of variation during HPE and non-HPE differed. Light scattering and atmospheric attenuation were proven to be associated with HPE, which possibly affected O3 photochemical reactions during HPE. Critical conversion time was used as the main determining factor when comparing HPE and non-HPE conditions. A possible screening effect that resulted in the shifting of the critical transformation point caused a delay of approximately of 15–30 min. The shifting was possibly influenced by the attenuation of sunlight in the morning during HPE. A negative correlation between O3 and PM10 was observed during the HPE in Klang in 2013 and 2014, with −0.87. Essentially, HPE with a high PM concentration altered ground-level O3 formation.

中文翻译：

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高颗粒物事件对地面臭氧临界转化点的时间效应

摘要 颗粒物 (PM)，尤其是空气动力学粒径小于 10 μm (PM10) 的颗粒物，通常是从跨界森林火灾中排放出来的。一场大规模的森林火灾可能会导致被称为高颗粒物事件 (HPE) 的雾霾状况，这种状况长期以来一直影响着东南亚，尤其是马来西亚半岛。这种事件可以改变二次污染物的光化学反应。这项工作研究了 PM 对 HPE 期间地面臭氧 (O3) 形成的影响。在 2013 年和 2014 年的 HPE 期间，本研究选择了位于马来西亚半岛不同地点类别（即工业、城市和背景）的五个连续空气质量监测站。 结果清楚地表明，HPE 期间的 O3 浓度显着高于非-HPE 在所有站点中。每个站点的 O3 昼夜变化表现出类似的模式，而 HPE 和非 HPE 期间的变化幅度不同。光散射和大气衰减被证明与 HPE 相关，这可能影响 HPE 期间的 O3 光化学反应。在比较 HPE 和非 HPE 条件时，临界转换时间被用作主要决定因素。可能的筛选效应导致临界转变点的移动，导致大约 15-30 分钟的延迟。这种转变可能受到 HPE 期间早晨阳光衰减的影响。在 2013 年和 2014 年巴生的 HPE 期间观察到 O3 和 PM10 之间的负相关，为 -0.87。从本质上讲，具有高 PM 浓度的 HPE 改变了地面 O3 的形成。