疫情背景下城市严控对我国春节期间空气质量的影响

Impact of Strict Urban Control on Air Quality during the Spring Festival in China under the Background of COVID-19 Epidemic

2020年春节因疫情防控需要,全国各市实行严格管控,空气质量特征也随之发生变化。利用2018年和2020年春节时段30天数据,构建增幅指数,对比分析了全国范围内PM_(2.5)时空格局、城市管控前后的变化及影响因素。结果表明:(1)两年春节期间,PM_(2.5)曲线特征相似,均呈尖帽形,初一02:00前后出现峰值,其他时间变化平稳,初一的PM_(2.5)浓度远高于基础浓度。(2)在疫情(2020)和非疫情(2018)年份,ST1段的PM_(2.5)浓度比ST1段分别降低26.97%、7.05%。对应的,受污染城市占比减少12.70%、2.52%,初一日增幅指数为81.2%、51.71%。空间上,疫情年份的污染格局相对稳定,而非疫情年份的污染格局变化较大。综合结果反映出城市严控可促进空气质量好转。(3)影响因素上,封城后空气质量改善与一次颗粒物排放和交通大量减少密切相关,除夕夜PM_(2.5)骤增则与烟花爆竹的集中燃放带来的大量颗粒物和SO2排放有关。人口数量越多、第二产业增加值越高的城市,封城后PM_(2.5)的降幅越显著,初一增幅指数越低,表明封城后人口集聚和工业排污不再是影响PM_(2.5)的主要因素。对于特定时期的大气污染治理来说,城市合理管控能使空气质量好转,在传承传统节日、节庆等的文化和习俗时需要更规范的城市管理政策和环保的节庆替代产品。

Due to the need of epidemic prevention and control during the Spring Festival(SF)in 2020,cities across the country exercised strict control and the characteristic of air quality also changed accordingly.Using the data during the SF in 2018 and 2020 to build the increase index,this paper compared and analyzed the spatial-temporal pattern of PM_(2.5),the changes and influencing factors before and after urban control.The results were shown as follows:(1)The curve features of PM_(2.5) during the SF in 2018 and 2020 were similar,with the shape of“pointed hat”,peaking at 2:00 am on the Lunar New Year’s Day(LNYD)and smoothly changing in the other 29 days,which resulted in the PM_(2.5) concentration on the LNYD being much higher than the basic concentration.(2)In the epidemic year(2020)and the nonepidemic year(2018),the PM_(2.5) concentrations in ST1 decreased by 26.97%and 7.05%respectively.Correspondingly,the number of polluted cities decreased by 12.70%and 2.52%respectively.The increase indexes on the LNYD were 81.2%and 51.71%,respectively.Spatially,the pollution pattern in the epidemic year was relatively stable,while that in the non-epidemic year changed greatly.Generally,the comprehensive results reflected that strict urban control could promote the improvement of air quality.(3)According to the correlation analysis of the influencing factors,the improvement of air quality after the closure of cities was closely related to the substantial reduction of the disposable emissions and traffic,while the sudden increase in PM_(2.5) concentration on New Year’s Eve was related to a lot of particulate matter and SO_(2) emitted by the centralized discharge of fireworks and firecrackers.Spatially,cities with more population and higher added value of secondary production had a more significant decline of PM_(2.5) concentration after lockdown and a lower increase index on the LNYD,which indicated that population agglomeration and industrial pollution were no longer the main factors affecting PM_(2.5) concentration when the cities were strictly control and managed.Regarding the control of air pollution in a specific period,reasonable urban management and control could improve air quality.Inheriting traditional culture and customs required more appropriate urban management policies and environmental festival alternatives.