The Impact of COVID-19 Confinement Measures on the Air Quality in an Urban-Industrial Area of Portugal

Carla Gamelas,Susana Marta Almeida,Leonor Abecasis,Nuno Canha

doi:10.3390/atmos12091097

Carla Gamelas, Susana Marta Almeida + Show 2 more

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https://doi.org/10.3390/atmos12091097

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Abstract

This study evaluated the temporal variability of the concentrations of pollutants (namely, NO2, O3, PM2.5, PM10 and SO2) in an urban-industrial area of mainland Portugal during two decades (from 2001 to 2020), to assess the impact of the COVID-19 pandemic on the levels of these atmospheric pollutants. Mean levels of pollutants in 2020 were compared with those measured in the six previous years (2014–2019). A significant improvement in air quality, namely regarding PM10 and NO2, was found and it can be attributable to the restrictions of anthropogenic activities (such as traffic) promoted during the March–May 2020 national lockdown that occurred due to the pandemic. Significant and expressive reductions of 44.0% and 40.3% were found in April 2020 for NO2 and PM10, respectively, showing the impact of local traffic in the study area. A similar trend of reduction for these pollutants was also found in the following months. However, ozone levels did not show the same trend, with significant increases in several months after the lockdown period, highlighting other contributions to this pollutant. This unique period can be considered as a living lab, where the implementation of strict measures due to COVID-19 confinement promoted the reduction of anthropogenic activities and allowed us to understand more comprehensively their impact on local air quality.

Highlights

In December 2019, an unknown disease was detected in Wuhan, China, and on11 March 2020, the World Health Organization (WHO) declared COVID-19—the disease caused by the new coronavirus SARS-CoV-2—as a pandemic
This work aimed to evaluate the temporal evolution of the concentration of the pollutants NO2, O3, PM2.5, PM10 and SO2 in an urban-industrial area in Portugal (Paio Pires, Seixal), from 2001 to 2020, and to assess the impact of the COVID-19 pandemic on the levels of these air pollutants
200 μg·m−3, which must not be exceeded more than 18 times a year, and an annual limit value (ALV) of 40 μg·m−3, both mandatory since 2010

Summary

Introduction

In December 2019, an unknown disease was detected in Wuhan, China, and on11 March 2020, the World Health Organization (WHO) declared COVID-19—the disease caused by the new coronavirus SARS-CoV-2—as a pandemic. To contain the SARS-CoV-2 virus, many countries have adopted drastic measures to reduce human interaction, including applying strict quarantines, encouraging social distancing, imposing a curfew and even closing entire cities [1]. These extreme measures led anthropogenic activities (such as production, traffic and transportation) almost to a standstill, with enormous socio-economic costs, but a clear short-term improvement in air quality has arisen, as shown, for instance, by satellite images that captured a sharp drop in NO2 pollution in several countries [2,3]. The number of studies published relating to Europe is more limited, but already point to similar reductions of air pollutants [6,7,8]

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