A two-pollutant strategy for improving ozone and particulate air quality in China
A two-pollutant strategy for improving ozone and particulate air quality in China
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改善中国臭氧和颗粒物空气质量的二污染物策略
DOI：
10.1038/s41561-019-0464-x
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发表时间：
2019-11-01
影响因子：
18.3
通讯作者：
Zhai, Shixian
中科院分区：
文献类型：
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作者：
Li, Ke;Jacob, Daniel J.;Zhai, Shixian
2013-2017年，在政府的清洁空气行动中，中国细颗粒物（PM2.5）下降了30-40%。然而，在同一时期，地面臭氧污染恶化。模式模拟表明，臭氧的增加可能是由PM2.5的减少所驱动的，因为PM2.5可以清除原本会产生臭氧的羟基（HO2）和氮氧化物自由基。在这里，我们用2013-2018年华北平原106个站点的每小时臭氧和PM2.5浓度数据展示了这种效应的观测证据。观测结果显示，在高PM2.5浓度下臭氧污染受到抑制，这与模型模拟结果一致，即PM2.5对HO2和NOx的清除作用相对于无PM2.5条件下使臭氧浓度降低了25 ppb。PM2.5的化学性质使得臭氧污染对氮氧化物排放控制的敏感性降低，强调了控制挥发性有机化合物（VOCs）排放的必要性，到目前为止，中国的挥发性有机化合物（VOCs）的排放并未减少。新的2018-2020年清洁空气行动计划要求将挥发性有机化合物排放量减少10%，即使PM2.5继续下降，也应该开始扭转长期臭氧增加的趋势。积极减少氮氧化物和芳香族挥发性有机化合物的排放对减少PM2.5和臭氧尤其有效。
Fine particulate matter (PM2.5) decreased by 30-40% across China during 2013-2017 in response to the governmental Clean Air Action. However, surface ozone pollution worsened over the same period. Model simulations have suggested that the increase in ozone could be driven by the decrease in PM2.5, because PM2.5 scavenges hydroperoxy (HO2) and NOx radicals that would otherwise produce ozone. Here we show observational evidence for this effect with 2013-2018 summer data of hourly ozone and PM2.5 concentrations from 106 sites in the North China Plain. The observations show suppression of ozone pollution at high PM2.5 concentrations, consistent with a model simulation in which PM2.5 scavenging of HO2 and NOx depresses ozone concentrations by 25 ppb relative to PM2.5-free conditions. PM2.5 chemistry makes ozone pollution less sensitive to NOx emission controls, emphasizing the need for controlling emissions of volatile organic compounds (VOCs), which so far have not decreased in China. The new 2018-2020 Clean Air Action plan calls for a 10% decrease in VOC emissions that should begin to reverse the long-term ozone increase even as PM2.5 continues to decrease. Aggressive reduction of NOx and aromatic VOC emissions should be particularly effective for decreasing both PM2.5 and ozone.