Abstract

This study investigates the changes of short-lived climate pollutants and other air pollutants during the COVID-19 pandemic in Tehran, Iran. Concentrations of air pollutants were obtained from 21 monitoring stations for the period from 5 January 2019 to 5 August 2019, representing normal conditions unaffected by COVID-19, and the period 5 January 2020 to 5 August 2020, i.e., during the COVID-19 crisis. We concentrated our analysis on three time windows (23 February 2020 to 15 March 2020, 18 March 2020 to 3 April 2020, and 5 April 2020 to 17 April 2020) during the lockdown when different sets of measures were taken to limit the spread of COVID-19. In comparison to the period not affected by COVID-19 measures, mean concentrations of pollutants were increased during the first lockdown period; when the number of COVID-19 patients increased sharply compared to the other periods, the mean surface concentrations of NO₂, SO₂, and CO were decreased and concentrations of other pollutants (i.e., O₃, PM₁₀, and PM_2.5) were increased during the second lockdown period compared to the corresponding period in 2019. In the third period, the mean concentrations were decreased compared to the corresponding period in 2019. For the full period, decreases in mean concentrations of O₃, NO₂, SO₂, CO, and PM₁₀ and increases in PM_2.5 were observed during the COVID-19 crisis, compared to 2019. Overall, the strongest reductions, 12% and 6%, respectively, were observed for CO and NO₂, pointing to reduced emissions from traffic as a result of lockdown measures. The concentrations of other pollutants changed little, suggesting that the lockdown measures did not result in strong changes in the emissions from stationary sources.

中文翻译：

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伊朗德黑兰 COVID-19 大流行期间短期气候污染物的变化

摘要

本研究调查了伊朗德黑兰 COVID-19 大流行期间短期气候污染物和其他空气污染物的变化。从 2019 年 1 月 5 日至 2019 年 8 月 5 日期间（代表未受 COVID-19 影响的正常情况）和 2020 年 1 月 5 日至 2020 年 8 月 5 日期间（即 COVID-19 危机期间）的 21 个监测站的空气污染物浓度. 我们将分析集中在三个时间窗口（2020 年 2 月 23 日至 2020 年 3 月 15 日、2020 年 3 月 18 日至 2020 年 4 月 3 日和 2020 年 4 月 5 日至 2020 年 4 月 17 日），当时采取了不同的措施来限制 COVID 的传播-19。与不受 COVID-19 措施影响的时期相比，在第一个封锁期间，污染物的平均浓度有所增加；_与2019年同期相比，第二次封城期间_二氧化硫、二氧化硫、一氧化碳下降，其他污染物（即O ₃、PM ₁₀和PM _2.5 ）浓度上升。与 2019 年同期相比有所下降。在整个期间，在 COVID-19 危机期间，观察到O ₃、NO ₂、SO ₂、CO 和 PM ₁₀的平均浓度下降，PM _{2.5上升，与2019. 总体而言，CO 和 NO 2}的降幅最大，分别为 12% 和 6%，指出由于封锁措施而减少了交通排放。其他污染物的浓度变化不大，这表明封锁措施并未导致固定源排放量发生重大变化。