COVID-19 lockdown measures affect air pollution from cities differently


Date:
April 26, 2022
Source:
American Institute of Physics
Summary:
Seizing on a natural experiment created by restricted travel,
researchers combine a network model with air pollution data before
and during outbreaks.



FULL STORY ==========================================================================
The COVID-19 pandemic and its public response created large shifts in
how people travel. In some areas, these restrictions on travel appear
to have had little effect on air pollution, and some cities have worse
air quality than ever.


==========================================================================
In Chaos, by AIP Publishing, researchers in China created a network
model drawn from the traffic index and air quality index of 21 cities
across six regions in their country to quantify how traffic emissions
from one city affect another.

They wanted to leverage data from COVID-19 lockdown procedures to better explain the relationship between traffic and air pollution and saw the
COVID-19 lockdowns as a rare opportunity for research.

"Air pollution is a typical 'commons governance' issue," said author
Jingfang Fan. "The impact of the pandemic has led cities to implement
different traffic restriction policies, one after another, which naturally forms a controlled experiment to reveal their relationship." To address
these questions, they turned to a weighted climate network framework to
model each city as a node using pre-pandemic data from 2019 and data from
2020. They added a two-layer network that incorporated different regions, lockdown stages, and outbreak levels.

Surrounding traffic conditions influenced air quality in
Beijing-Tianjin-Hebei, the Chengdu-Chongqing Economic Circle, and central
China after the outbreak.

Pollution tended to peak in cities as they made initial progress for
containing the virus.

During this time, pollution in Beijing-Tianjin-Hebei and central China
lessened over time. Beijing-Tianjin-Hebei, however, saw another spike
as control measures for outbound traffic from Wuhan and Hubei were lifted.

"Air pollution in big cities, such as Beijing and Shanghai, is more
affected by other cities," said author Saini Yang. "This is contrary to
what we generally think, that air pollution in big cities is mainly caused
by its own conditions, including the traffic congestion." Author Weiping
Wang hopes the team's work inspires other interdisciplinary teams to
explore unique ways to explore problems in environmental science. They
will look to improve their model with a higher degree of detail for
traffic emissions.

"Our discovery is that in order to improve air pollution, it is not
only necessary to improve and reduce our own urban traffic and increase
green travel, but also need the joint efforts of surrounding cities,"
said author Na Ying. "Everyone is important in the governance of commons."

========================================================================== Story Source: Materials provided by American_Institute_of_Physics. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Weiping Wang, Saini Yang, Kai Yin, Zhidan Zhao, Na Ying, Jingfang
Fan.

Network approach reveals the spatiotemporal influence of traffic on
air pollution under COVID-19. Chaos: An Interdisciplinary Journal
of Nonlinear Science, 2022; 32 (4): 041106 DOI: 10.1063/5.0087844 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/04/220426153709.htm

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