Even if the people density, habits and displacements probably represent the most important causes of the SARS-Cov-2 virus propagation, the role of the atmospheric aerosol needs to be investigated. Therefore, we aimed to study if the aerosol properties related to the different sources and meteorological conditions we can observe in urbanized areas can have an influence on in the atmospheric transport of the SARS-Cov-2 virus. This paper focuses on the lockdown period to reduce the differences in the social behavior. As an example, we investigated the contamination cases during March 2020 in two specific French areas located in both continental and coastal areas with regard to the meteorological conditions and the corresponding aerosol properties. To this end, we used both the optical depth (AOD) and the Angstrom exponent provided by the AERONET network. The results show that the analysis of aerosol ground-based data can be of interest to assess a virus survey. In particular, our data show that moderate to strong onshore winds occurring in coastal regions, which allow large sea-spray production episodes, deal with smaller COVID-19 contamination rates. This is probably due to the fact that the coagulation of SARS-Cov-2 particles with hygroscopic salty sea-spray aerosols would tend to inhibit its viral infectivity via possible reaction with NaCl, especially in high relative humidity environments. In contrast, out results confirm that the atmospheric transport of the SARS-Cov-2 can be favored by its coagulation with anthropogenic aerosols, which protects the virus particle from ambient humidity and preserves its infectivity.Capsule: Our results suggest that maritime air-masses limit the SARS-Cov-2 impact via the role of the sea-spray.

Background: Even if the people density, habits and displacements probably represent the most important causes of the SARS-Cov-2 virus propagation, the role of the atmospheric aerosol needs to be investigated. Therefore, we aimed to study if the aerosol properties related to the different sources and meteorological conditions we can observe in urbanized areas can have an influence on in the atmospheric transport of the SARS-Cov-2 virus. This study focuses on the lockdown period to reduce the differences in the social behavior.Methods: We have investigated the contamination cases of four specific geographic areas, two in France and two in Italy, located in both continental and coastal areas with regard to the meteorological conditions and the corresponding air mass properties. To this end, we used a survey of meteorological conditions and aerosol properties via both the optical depth (AOD) and Angstrom exponent retrievals for these locations during March 2020. Results: The results show that the analysis of aerosol ground-based data can be of interest to assess a virus survey. In particular, our data show that moderate to strong onshore winds occurring in coastal regions, which allow large sea-spray production episodes deal with smaller COVID-19 contamination rates. One possible reason is the coagulation of SARS-Cov-2 particles with hygroscopic salty sea-spray aerosols that would tend to inhibit its viral infectivity in environments with high relative humidity via possible reaction with NaCl. Conclusions: In this paper, we hypothesize that marine atmosphere conditions tend to decrease virus infectivity. In contrast, the atmospheric transport of the SARS-Cov-2 can be favored by its coagulation with anthropogenic aerosols, which protects the virus particle from ambient humidity and preserves its infectivity.