Different approaches to explore the impact of COVID-19 lockdowns on carbonaceous aerosols at a European rural background site

• Published in: The Science of the total environment Vol. 892; p. 164527
• Main Authors: Mbengue, Saliou, Vodička, Petr, Komínková, Kateřina, Zíková, Naděžda, Schwarz, Jaroslav, Prokeš, Roman, Suchánková, Lenka, Julaha, Kajal, Ondráček, Jakub, Holoubek, Ivan, Ždímal, Vladimír
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 20.09.2023; Published by Elsevier B.V
• Subjects: Aged; Air Pollutants - analysis; Atmospheric aerosols; Carbon - analysis; China; Communicable Disease Control; COVID-19 - prevention & control; COVID-19 lockdowns; Environmental Monitoring; Humans; Organic - elemental carbon; Particulate Matter - analysis; Respiratory Aerosols and Droplets; Rural background site; Seasons; Temporal variation; Vertical distribution; China; Organic - elemental carbon; Temporal variation; COVID-19 lockdowns; Vertical distribution; Rural background site; Atmospheric aerosols
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2023.164527

To prevent the fast spread of COVID-19, worldwide restrictions have been put in place, leading to a reduction in emissions from most anthropogenic sources. In this study, the impact of COVID-19 lockdowns on elemental (EC) and organic (OC) carbon was explored at a European rural background site combining different approaches: − “Horizontal approach (HA)” consists of comparing concentrations of pollutants measured at 4 m a.g.l. during pre-COVID period (2017–2019) to those measured during COVID period (2020-2021); − “Vertical approach (VA)” consists of inspecting the relationship between OC and EC measured at 4 m and those on top (230 m) of a 250 m-tall tower in Czech Republic. The HA showed that the lockdowns did not systematically result in lower concentrations of both carbonaceous fractions unlike NO2 (25 to 36 % lower) and SO2 (10 to 45 % lower). EC was generally lower during the lockdowns (up to 35 %), likely attributed to the traffic restrictions whereas increased OC (up to 50 %) could be attributed to enhanced emissions from the domestic heating and biomass burning during this stay-home period, but also to the enhanced concentration of SOC (up to 98 %). EC and OC were generally higher at 4 m suggesting a greater influence of local sources near the surface. Interestingly, the VA revealed a significantly enhanced correlation between EC and OC measured at 4 m and those at 230 m (R values up to 0.88 and 0.70 during lockdown 1 and 2, respectively), suggesting a stronger influence of aged and long distance transported aerosols during the lockdowns. This study reveals that lockdowns did not necessarily affect aerosol absolute concentrations but it certainly influenced their vertical distribution. Therefore, analyzing the vertical distribution can allow a better characterization of aerosol properties and sources at rural background sites, especially during a period of significantly reduced human activities. [Display omitted] •Impact of lockdowns was explored combining Horizontal and Vertical approaches.•Lockdowns did not always lead to lower levels of EC and OC, unlike NO2 and SO2.•EC was generally lower during the lockdowns (up to 35 %) due to traffic restrictions.•Higher OC (up to 50 %) associated to enhanced domestic activities and higher SOC.•Lockdowns influenced the vertical distribution of EC and OC.