How have surface NO2 concentrations changed as a result of the UK's COVID-19 travel restrictions?
How have surface NO2 concentrations changed as a result of the UK's COVID-19 travel restrictions?
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DOI：
10.1088/1748-9326/abb6a2
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发表时间：
2020-10-01
影响因子：
6.7
通讯作者：
Neal, L. S.
中科院分区：
文献类型：
--
作者：
Dacre, H. F.;Mortimer, A. H.;Neal, L. S.
COVID-19大流行造成的限制导致英国道路上的车辆减少。由于燃料燃烧占英国排放的很大一部分，因此预计表面二氧化氮浓度将因此降低。然而，在英国部分地区，在实施旅行限制后，表面二氧化氮浓度有所增加。来自142个自动城市和农村网络站点的二氧化氮测量数据与气象局高分辨率天气预报模型的气象数据相结合，建立了特定站点的模型。这些模型在排放没有变化的情况下预测二氧化氮浓度。结果表明，气象变化和排放变化都对观测到的NO2浓度变化有贡献。如果排放没有变化，那么封锁线前后的气象变化将导致二氧化氮浓度平均增加6%。相反，排放的变化将导致NO2浓度平均下降-18%，从而导致观测到的NO2浓度总变化-12%。然而，在一些地点，由于气象原因，排放量的减少小于二氧化氮浓度的增加。与气象变化相关的最大增加出现在农村地区（+20%），那里的二氧化氮测量具有大面积代表性，因此主要是来自欧洲的二次二氧化氮的区域平流。相反，与减少排放相关的最大降幅出现在城市交通和城市背景站点（分别为-27%和-14%），其中二氧化氮浓度代表了当地，因此主要是当地车辆排放的减少。随着封锁措施的放松，二氧化氮浓度可能会恢复到新冠肺炎前的水平，但这些结果表明，我们行为的改变可以对空气质量产生积极影响，并说明城市地区减少出行战略的有效性。
Restrictions as a result of the COVID-19 pandemic have led to fewer vehicles on UK roads. Since fuel combustion is responsible for a large fraction of UK emissions it is expected that surface NO2 concentrations would reduce as a result. However, over parts of the UK, surface NO2 concentrations have increased following the implementation of travel restrictions. NO2 measurements from 142 Automatic Urban and Rural Network sites are combined with meteorological data from the Met Office high-resolution weather prediction model to build site specific models. These models predict NO2 concentrations given no change in emissions. It is found that both meteorological and emission changes contribute to the observed changes in NO2 concentrations. Given no change in emissions, changes in meteorology between pre- and post-lockdown periods would have led to a mean increase in NO2 concentrations of +6%. Conversely, changes in emissions would have led to a mean reduction in NO2 concentrations of -18%, resulting in the observed total change in NO2 concentrations of -12%. However at some sites the reduction in emissions is smaller than the increase in NO2 concentrations due to meteorology. The largest increases associated with changes in the meteorology are seen at rural sites (+20%) where NO2 measurements are representative of large areas and thus dominated by the regional advection of secondary NO2 from Europe. Conversely, the largest decreases associated with reduced emissions are found at urban traffic and urban background sites (-27% and -14% respectively) where NO2 concentrations are representative of local areas and thus dominated by local reduction in emissions from vehicles. As lockdown measures are relaxed, NO2 concentrations are likely to return to pre-COVID levels, but these results demonstrate that changes in our behaviour can result in positive impacts on air quality and illustrate the effectiveness of travel-reducing strategies in urban areas.