Assessment of the COVID-19 Lockdown Effects on Spectral Aerosol Scattering and Absorption Properties in Athens, Greece
Open Access
- 8 February 2021
- journal article
- research article
- Published by MDPI AG in Atmosphere
- Vol. 12 (2), 231
- https://doi.org/10.3390/atmos12020231
Abstract
COVID-19 is evolving into one of the worst pandemics in recent history, claiming a death toll of over 1.5 million as of December 2020. In an attempt to limit the expansion of the pandemic in its initial phase, nearly all countries imposed restriction measures, which resulted in an unprecedented reduction of air pollution. This study aims to assess the impact of the lockdown effects due to COVID-19 on in situ measured aerosol properties, namely spectral-scattering (bsca) and absorption (babs) coefficients, black carbon (BC) concentrations, single-scattering albedo (SSA), scattering and absorption Ångström exponents (SAE, AAE) in Athens, Greece. Moreover, a comparison is performed with the regional background site of Finokalia, Crete, for a better assessment of the urban impact on observed differences. The study examines pre-lockdown (1–22 March 2020), lockdown (23 March–3 May 2020) and post-lockdown (4–31 May 2020) periods, while the aerosol properties are also compared with a 3–4 year preceding period (2016/2017–2019). Comparison of meteorological parameters in Athens, between the lockdown period and respective days in previous years, showed only marginal variation, which is not deemed sufficient in order to justify the notable changes in aerosol concentrations and optical properties. The largest reduction during the lockdown period was observed for babs compared to the pre-lockdown (−39%) and to the same period in previous years (−36%). This was intensified during the morning traffic hours (−60%), reflecting the large decrease in vehicular emissions. Furthermore, AAE increased during the lockdown period due to reduced emissions from fossil-fuel combustion, while a smaller (−21%) decrease was observed for bsca along with slight increases (6%) in SAE and SSA values, indicating that scattering aerosol properties were less affected by the decrease in vehicular emissions, as they are more dependent on regional sources and atmospheric processing. Nighttime BC emissions related to residential wood-burning were slightly increased during the lockdown period, with respect to previous-year means. On the contrary, aerosol and pollution changes during the lockdown period at Finokalia were low and highly sensitive to natural sources and processes.Funding Information
- PANhellenic infrastructure for Atmospheric Composition and climatE change (MIS 5021516)
This publication has 135 references indexed in Scilit:
- Identification of key aerosol populations through their size and composition resolved spectral scattering and absorptionAtmospheric Chemistry and Physics, 2013
- Global and diffuse shortwave irradiance during a strong desert dust episode at Granada (Spain)Atmospheric Research, 2012
- Road traffic emissions impact on air quality of the Greater Athens Area based on a 20year emissions inventoryScience of The Total Environment, 2011
- Long term measurements of atmospheric aerosol optical properties in the Eastern MediterraneanAtmospheric Research, 2011
- Black carbon aerosol mixing state, organic aerosols and aerosol optical properties over the United KingdomAtmospheric Chemistry and Physics, 2011
- Design and performance of a three-wavelength LED-based total scatter and backscatter integrating nephelometerAtmospheric Chemistry and Physics, 2011
- Primary and secondary contributions to aerosol light scattering and absorption in Mexico City during the MILAGRO 2006 campaignAtmospheric Chemistry and Physics, 2009
- Light scattering and absorption properties of aerosol particles in the urban environment of Granada, SpainAtmospheric Environment, 2008
- Seasonal variability of optical properties of aerosols in the Eastern MediterraneanAtmospheric Environment, 2005
- Determining Aerosol Radiative Properties Using the TSI 3563 Integrating NephelometerAerosol Science and Technology, 1998