Mobility restrictions can have unexpected impacts on air quality

Date:
July 22, 2021
Source:
University of Helsinki
Summary:
Reduced mobility induced by the COVID-19 restrictions had only minor
influence on particulate pollution levels, according to atmosphere
studies in the Po Valley region of northern Italy. Eventually
computer simulations indicated that the change in air quality led
to an increase in secondary aerosol formation.



FULL STORY ==========================================================================
An international collaborative study led by University of Helsinki
has conducted a holistic study to investigate the effects of COVID-19 restrictions on several air quality pollutants for the Po Valley region
in northern Italy.

The area is well known to have one of the worst air quality standards
in Europe and is highly influenced by anthropogenic (human-led)
activities. The study was done between research groups in Finland,
Italy and Switzerland and the results were published in the journal Environmental Science: Atmospheres.


========================================================================== Scientists have combined air quality measurements and computer simulation
data over several locations in the region. The resulting studies
show that reduced emissions from traffic lead to a strong reduction of
nitrogen oxides, while have had limited impact on aerosol concentrations, contributing to a better understanding of how the air pollution is formed
in the Po Valley.

The studies show that despite the large reduction in mobility of people
and emissions from cars (which raise for instance nitrogen oxides concentrations), aerosols concentrations remained almost unchanged
compared to previous years.

Secondary formed pollutants like ozone, on the other hand, showed an
increase in concentrations. These findings were confirmed by a computer
model simulation that simulates the COVID-19 restriction on traffic,
indicating that the increased overall oxidation capacity of the atmosphere might have enhanced the formation of new aerosols.

Furthermore, model simulations indicated that as nitrogen oxides
emissions were largely reduced, chemical reactions of organic gases
against atmospheric oxidants increased, slightly favoring the formation
of new organic particles.

"You can think of the Po Valley region as a massive batch reactor with
all sort of chemicals. Altering one of the "ingredients" can trigger
non-linear responses in air pollutants concentrations," says Dr Federico Bianchi from the Institute for Atmospheric and Earth System Research
(INAR) of University of Helsinki.

These studies shade new lights on the formation of air pollutants in
the Po Valley region and on their sources. The conclusion is that the
reduction in traffic emissions had little impact on particulate matter concentrations, possibly highlighting the importance of other emissions
sources in the Po Valley area.

Carefully characterizing the evolution of such emission categories are
of a vital importance to improve the understanding of the air pollution
and to reduce the uncertainties in future air quality scenarios.

========================================================================== Story Source: Materials provided by University_of_Helsinki. Original
written by Paavo Ihalainen. Note: Content may be edited for style
and length.


========================================================================== Journal Reference:
1. Giancarlo Ciarelli, Jianhui Jiang, Imad El Haddad, Alessandro Bigi,
Sebnem Aksoyoglu, Andre' S. H. Pre'vo^t, Angela Marinoni, Jiali
Shen, Chao Yan, Federico Bianchi. Modeling the effect of reduced
traffic due to COVID-19 measures on air quality using a chemical
transport model: impacts on the Po Valley and the Swiss Plateau
regions. Environmental Science: Atmospheres, 2021; 1 (5): 228 DOI:
10.1039/D1EA00036E ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/07/210722112935.htm

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