Variation of Aerosol Pollution in Peru during the Quarantine Due to COVID-19

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(IJACSA) International Journal of Advanced Computer Science and Applications,
Vol. 11, No. 4, 2020
47 | Page
www.ijacsa.thesai.org
Variation of Aerosol Pollution in Peru during
the Quarantine Due to COVID-19
Avid Roman-Gonzalez1*, Natalia I. Vargas-Cuentas2
Image Processing Research Laboratory (INTI-Lab), Universidad de Ciencias y Humanidades, Lima, Peru1, 2
Aerospace Sciences & Health Research Laboratory (INCAS-Lab), Universidad Nacional Tecnológica de Lima Sur1
Abstract—Due to COVID-19, which is a type of pneumonia
produced by a coronavirus family virus, the Peruvian
government has decreed mandatory social isolation. This
isolation is extended until 26 April 2020. Due to this situation,
people must stay at home and only go out to make purchases to
cover basic needs. This situation, between other things, probably
causes pollution reduction that is important for our ecosystem. In
Peru, there is not a measurable way to quantify the impact of
social isolation on air pollution. The present work aims to show
more objectively how much decrease the aerosol pollution in
Peru. For this purpose, one uses remote sensing data from
Copernicus Data Hub of the European Space Agency,
specifically, Sentinel-5 Precursor satellite. The results show an
essential reduction of aerosol pollution in different regions of
Peru, especially in Lima and the Amazon regions.
Keywords—COVID-19; coronavirus; pollution; Sentinel-5P;
Peru
I. INTRODUCTION
COVID-19 is a disease that started in December 2019 in
Wuhan, China [1]. COVID-19 is a type of pneumonia
produced by a virus belonging to the coronavirus family that
affects the pulmonary alveoli and generates respiratory failure
[1, 2]. According to reports from the World Health
Organization (WHO) [3], for 22 April 2020, after China, the
outbreak has globally reached 2 471 136 cases and 169 006
deaths. In Fig. 1, one can observe a global map about the
impact of the COVID-19 around the World.
Due to the rapid spread of contagion, on 11 March 2020,
WHO declared COVID-19 as a pandemic. This declaration
was in an opening address by the WHO General Director for a
press conference [4].
In Peru, the first case was reported by President Martin
Vizcarra at a press conference on Friday, 6 March, 2020 [5].
The evolution in Peru from the first case of COVID-19 has an
exponential trend and it is shown in Fig. 2.
Fig. 2 shows the evolution of total cases (curve in blue),
new cases per day (bend in gray), total cases recovered (curve
in cyan), active cases (line in intense blue), and total deaths
(curve in red). Active cases are calculated as the subtraction of
the total cases, minus the recovered cases, minus the deceased.
Deaths curve is according to right axis, and the other curves
are according to left axis. Currently, at 22 April 2020, Peru
has 19 250 total cases, 7 027 recovered cases, 11 693 active
cases, and 530 deaths.
Due to this situation of the first cases of COVID-19 in
Peru and to try to avoid an exponential growth in the number
of cases, the President of Peru, Martin Vizcarra, announced
the Supreme Decree that declares a State of National
Emergency for 15 days [6, 7]. This State of Emergency was
reported on March 15, 2020. This declaration implies, among
other things, the restriction of the exercise of constitutional
rights related to personal liberty and security, the inviolability
of the home, and the freedom of meeting and transit in the
territory. In this State of Emergency, people are in quarantine;
however, the supply of food and medicine is guaranteed.
Although the increase in the number of cases has been
somewhat halted compared to projections established with the
experience of other countries, the Peruvian government has
decided to extend the State of Emergency until April 26, 2020
[8].
Fig. 1. Countries with Reported Cases of COVID-19, 22 April 2020,
®WHO, [3].
Fig. 2. Evolution of the COVID-19 Cases in Peru, 22 April 2020.
*Corresponding Author

(IJACSA) International Journal of Advanced Computer Science and Applications,
Vol. 11, No. 4, 2020
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In this State of Emergency, people have remained in their
homes most of the time. So it has been possible to visualize
that the natural ecosystem has recovered. This recovery
implies a cleaner sky, clearer waters, return of marine spices
to the Sea of Grau, among other aspects [9].
Regarding all the aforementioned, the objective of this
work is to measure in a more objective and visible way the
reduction of air pollution by aerosols in Peru.
Aerosols are pollutants because they contain substances
that, in contact with sunlight, produce polluting gases.
Changes in weather may occur. It also affects people's health
[10].
Remote sensing is an excellent option to assess air
pollution by taking a global view of the area to be analyzed.
Measuring aerosols is a good option, as does Gitahi et al. [11],
who use high-resolution satellite images such as Sentinel-2
images. In that work, they extract the Aerosol Optical Depth
(AOD) from the Sentinel-2 images and compare them with
measurements from 2 Aerosol Robotic Network (AERONET)
stations for the city of Munich, Germany. The results they
obtained show a strong consistency between both analyses,
which shows the feasibility of using Sentinel-2 satellite
images for this type of purpose.
Another work that uses Lansat-8 and Sentinel-2 images is
the one presented by Li et al. [12]. In that work, the data
obtained from the satellite images are also compared with the
data from the AERONET stations. The results they got show
that the AOD obtained from the Sentinel-2 images have better
precision than the AOD from the Landsat-8 images.
On the other hand, Theys et al. [13] use Sentinel-5
Precursor (also called as Sentinel-5P) images for monitoring
volcanic gases.
As can be seen, satellite images can be used effectively in
monitoring air pollution, and having a platform to interact and
to access images, like the one presented in [14], could be a
great help.
The continuation of this research work is as follows,
Section II shows the methodology to be followed and the used
tool for the analysis, Section III presents the obtained results,
and finally, Section IV gives the discussion and conclusions of
the work.
II. METHODOLOGY
For this research work, one will use satellite images from
the Copernicus program of the European Union, specifically
Sentinel-5 Precursor (Sentinel-5P) images.
The methodology to be followed will be based on the
works presented in [13, 15]. The idea is to collect a database
of images of the region of interest (Peru); read the images and
values get from the satellite; finally, mapping the result and
compare them.
In the following sub-section, one describes the followed
methodology.
A. Sentinel-5 Precursor Images
Also known as Sentinel-5P, it was launched on October
13, 2017. Sentinel-5P's main objective is the atmospheric
monitoring of our planet [16, 17].
The Sentinel-5P payload is the TROPOspheric Monitoring
Instrument (TROPOMI). TROPOMI is a hyperspectral
spectrometer. Fig. 3 is an artistic representation of the satellite
Sentinel-5P.
Some specifications of the mission that we can mention
are the following [15, 16]:
● Sentinel-5P will provide measurements of:
○ Ozone
○ NO_2 (nitrogen dioxide)
○ SO_2 (sulfur dioxide)
○ Formaldehyde
○ Aerosol
○ Carbonmonoxide
○ Methane
○ Clouds
● Mission Orbit:
○ Orbit Type: Sun-synchronous, polar
○ Orbit Height: 824 km
To download Sentinel-5P images and create the database,
one uses the Copernicus Open Access Hub of the European
Space Agency (ESA). In Fig. 4, one can see a screenshot of
the Hub.
Fig. 3. Sentinel-5P © ESA.
Fig. 4. Copernicus Open Access Hub.

(IJACSA) International Journal of Advanced Computer Science and Applications,
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For the present work, images measuring Aerosol
(L2__AER_AI), of the level L2, have been downloaded from
March 11 to March 26, 2020. In other words, one has five
images before quarantine and ten images during the
quarantine.
B. VISAN
For the processing and visualization of the images, the
VISAN tool will be used. VISAN is a cross-platform for
visualization and analysis applications for atmospheric data.
VISAN uses the Python language as the means through which
one can provide commands. The Python interfaces for CODA
and HARP are included, so one can directly ingest product
data from within VISAN. Also, VISAN delivers some robust
visualization functionality for 2D and world plots [15]. Fig. 5
shows a screenshot of the principal windows of the VISAN
tool.
Fig. 5. VISAN Platform.
For this project, the version 4.0 of the VISAN and the
version 3.8.2 of Python.
One uses commands like: harp.import_product and wplot
among others to read, analyze, and mapping the obtained
results.
III. RESULTS
After processing and analysis, the visualization can be
seen in Fig. 6. It can be seen that before the obligatory
isolation measurement, the levels of southern surface wind
velocity (m / s) in Peru had few cyan regions. Ten days after
the declaration of a state of national emergency, the cyan areas
have increased. Fig. 6 is a heat map where the red zone
represents polluted areas, and cyan and blue areas represent
areas with less pollution.
The highest levels are seen in shades of red, and the lowest
levels are seen in shades of blue.
Fig. 6. Variation of Aerosol Contamination in Peru Due to Quarantine by
COVID-19.
IV. DISCUSSION AND CONCLUSION
As can be seen in the results obtained after the processing,
analysis, and visualization of Sentinel-5P images, air pollution
in Peru during the first ten days of quarantine due to COVID-
19, has decreased. Some regions have a more significant
decrease than others, but in general, a reduction can be noticed
throughout the country. This decrease is essential for the
planet. As well as in Peru, in other countries, there has also
been a decrease in pollution. This situation allows the
ecosystem to recover and nature to breathe.
The decrease will be much more noticeable as the days go
by, as already mentioned, the quarantine in Peru was extended
until April 26.
It is also possible to monitor SO2, O3, NO2, Methane,
among other parameters. In a future work the idea is to
analyse all parameters.
The main contribution of this work is to demonstrate the
positive impact of quarantine on the environment objectively.
The evolution of the cases of COVID-19 in Peru shows a
small reduction in the trend of change for the last days. New
cases per day are around 1000. In the previous week, there is a
slow growth of recovered people, so active cases continue to
increase. The increase in the number of cases is also due to the
increase in the number of tests, since in Peru molecular tests
and rapid tests are currently being used.
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Vol. 11, No. 4, 2020
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