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Significant reduced traffic in Beijing failed to relieve haze pollution during the COVID-19 lockdown: implications for haze mitigation. (arXiv:2006.07297v1 [physics.ao-ph])

[Submitted on 12 Jun 2020] Authors:Zhaofeng Lv (1), Xiaotong Wang (1), Fanyuan Deng (1), Qi Ying (2), Alexander T. Archibald (3), Roderic L. Jones (3), Yan Ding (4), Ying Cheng (5), Mingliang Fu (4), Ying Liu (5), Hanyang Man (1), Zhigang Xue (4), Kebin He (1), Jiming Hao (1), Huan Liu (1) ((1) State Key…

[Submitted on 12 Jun 2020]

Authors: Zhaofeng Lv (1), Xiaotong Wang (1), Fanyuan Deng (1), Qi Ying (2), Alexander T. Archibald (3), Roderic L. Jones (3), Yan Ding (4), Ying Cheng (5), Mingliang Fu (4), Ying Liu (5), Hanyang Man (1), Zhigang Xue (4), Kebin He (1), Jiming Hao (1), Huan Liu (1) ((1) State Key Joint Laboratory of ESPC, State Environmental Protection Key Laboratory of Sources and Control of Air Pollution Complex, International Joint Laboratory on Low Carbon Clean Energy Innovation, School of the Environment, Tsinghua University, China, (2) Zachry Department of Civil and Environmental Engineering, Texas A&M University, USA, (3) Centre for Atmospheric Science, Department of Chemistry, University of Cambridge, UK, (4) Chinese Research Academy of Environmental Sciences, (5) Beijing Transport Institute)

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Abstract: The COVID-19 outbreak greatly limited human activities and reduced primary
emissions particularly from urban on-road vehicles, but coincided with Beijing
experiencing pandemic haze, raising the public concerns of the validity and
effectiveness of the imposed traffic policies to improve the air pollution.
Here, we explored the relationship between local vehicle emissions and the
winter haze in Beijing before and during the COVID-19 lockdown period based on
an integrated analysis framework, which combines a real-time on-road emission
inventory, in-situ air quality observations and a localized chemical transport
modeling system. We found that traffic emissions decreased substantially
affected by the pandemic, with a higher reduction for NOx (75.9%, 125.3 Mg/day)
compared to VOCs (53.1%, 52.9 Mg/day). Unexpectedly, our results show that the
imbalanced emission abatement of NOx and VOCs from vehicles led to a
significant rise of the atmospheric oxidizing capacity in urban areas, but only
resulting in modest increases in secondary aerosols due to the inadequate
precursors. However, the enhanced oxidizing capacity in the surrounding regions
greatly increased the secondary particles with relatively abundant precursors,
which is mainly responsible for Beijing haze during the lockdown period. Our
results indicate that the winter haze in Beijing was insensitive to the local
vehicular emissions reduction due to the complicated nonlinear response of the
fine particle and air pollutant emissions. We suggest mitigation policies
should focus on accelerating VOC and NH3 emissions reduction and synchronously
controlling regional sources to release the benefits on local traffic emission
control.

Submission history

From: Huan Liu [view email]

[v1]
Fri, 12 Jun 2020 16: 25: 46 UTC (2,774 KB)

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