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. 2021 Jun 23;18(13):6748.
doi: 10.3390/ijerph18136748.

The Impact of the Lockdown Caused by the COVID-19 Pandemic on the Fine Particulate Matter (PM2.5) Air Pollution: The Greek Paradigm

Ourania S Kotsiou  1   2 , Georgios K D Saharidis  3 , Georgios Kalantzis  3 , Evangelos C Fradelos  2 , Konstantinos I Gourgoulianis  1
Affiliations

The Impact of the Lockdown Caused by the COVID-19 Pandemic on the Fine Particulate Matter (PM2.5) Air Pollution: The Greek Paradigm

Ourania S Kotsiou et al. Int J Environ Res Public Health. .

Abstract

Introduction: Responding to the coronavirus pandemic, Greece implemented the largest quarantine in its history. No data exist regarding its impact on PM2.5 pollution. We aimed to assess PM2.5 levels before, during, and after lockdown (7 March 2020-16 May 2020) in Volos, one of Greece's most polluted industrialized cities, and compare PM2.5 levels with those obtained during the same period last year. Meteorological conditions were examined as confounders.

Methods: The study period was discriminated into three phases (pre-lockdown: 7 March-9 March, lockdown: 10 March-4 May, and post-lockdown period: 5 May-16 May). A wireless sensors network was used to collect PM2.5, temperature, relative humidity, rainfall, and wind speed data every 2 s.

Results: The lockdown resulted in a significant drop of PM2.5 by 37.4% in 2020, compared to 2019 levels. The mean daily concentrations of PM2.5 exceeded the WHO's guideline value for 24-h mean levels of PM2.5 35% of the study period. During the strictest lockdown (23 March to 4 May), the mean daily PM2.5 levels exceeded the standard 41% of the time. The transition from the pre-lockdown period into lockdown or post-lockdown periods was associated with lower PM2.5 concentrations.

Conclusions: A reduction in the mean daily PM2.5 concentration was found compared to 2019. Lockdown was not enough to avoid severe exceedances of air pollution in Volos.

Keywords: Greece; GreenYourAir; air pollution; coronavirus disease 2019; fine particulate matter.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
GreenYourAir device 1178/PM2.5.
Figure 2
Figure 2
Zones of the city of Volos (A) and division into zones according to the density of traffic (B).
Figure 3
Figure 3
The sub-areas of the city of Volos selected for the placement of the sensors.
Figure 4
Figure 4
The optimal sensor placement according to the mathematical model (twelve sensors) (A) and the actual placement of sensors (twelve sensors) (B).
Figure 5
Figure 5
The trend of PM2.5 concentration in the city of Volos, Central Greece, from 7 March to 16 May 2020, compared to PM2.5 concentrations during the same period in 2019. The horizontal red dashed line identifies the PM2.5 concentration at 25 μg/m3 set as a safe limit by the World Health Organization air quality guidelines. The dotted dash vertical lines indicate the start of each phase of the three-step approach to combat the COVID-19 wave. Phase 1 (pre-lockdown period): 7 March–9 March, Phase 2 (lockdown period): 10 March–4 May, and Phase 3 (post-lockdown period): 5 May–16 May. The vertical black dashed line represents the initiation of the strictest period amid phase 2 (23 March 2020).
Figure 6
Figure 6
Correlations between meteorological variables and PM2.5 air pollution.
See this image and copyright information in PMC

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