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. 2021 Apr:195:110863.
doi: 10.1016/j.envres.2021.110863. Epub 2021 Feb 17.

Determination of SARS-CoV-2 RNA in different particulate matter size fractions of outdoor air samples in Madrid during the lockdown

Beatriz Linillos-Pradillo  1 , Lisa Rancan  2 , Elías Díaz Ramiro  3 , Elena Vara  2 , Begoña Artíñano  3 , Javier Arias  4
Affiliations

Determination of SARS-CoV-2 RNA in different particulate matter size fractions of outdoor air samples in Madrid during the lockdown

Beatriz Linillos-Pradillo et al. Environ Res. 2021 Apr.

Abstract

Background: Previous studies described the presence of SARS-CoV-2 in outdoor air particulate matter (PM) in urban areas of northern Italy and USA. The city of Madrid was heavily affected by COVID-19 during March-June 2020. Also, this city usually displays high concentrations of PM under several atmospheric situations. This is mandatory to assess the presence of viral RNA in PM, as an indicator of epidemic recurrence. Our study was aimed at investigating the presence of SARS-CoV-2 RNA in outdoor air samples (on PM10, PM2.5 and PM1).

Methods: Six samples of PM10, PM2.5 and PM1 were collected between the May 4th and 22nd 2020 in Madrid, on quartz fiber filters by using MCV high volume samplers (30 m3 h-1 flow) with three inlets (Digitel DHA-80) for sampling PM10, PM2.5 and PM1. RNA extraction and amplification was performed according to the protocol recently set by Setti et al.2020c in Italy. Up to three highly specific molecular marker genes (N1, N2, and RP) were used to test the presence of SARS-CoV-2 RNA.

Results: After RNA extraction and expression measurements of N1, N2 and RP genes from all the collected filters, no presence of SARS-CoV-2 RNA was observed. Control tests to exclude false positive results were successfully accomplished.

Conclusions: No presence of SARS-CoV-2 in quartz fiber filters samplers for PM10, PM2.5 and PM1 fractions was observed in our study carried out in Madrid during the month of May 2020. Nevertheless, the absence of viral genomes could be due to different factors including: limited social interactions and economic activities resulting in reduced circulation of the coronavirus, lower daily PM concentration in outdoor air, as well as to meteorological stability and higher temperature that characterize spring season. Further research should be carried out during winter, in presence of higher viral circulation and daily PM exceedances.

Keywords: Air pollution; COVID-19; Madrid; Particulate matter; SARS-CoV-2.

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Conflict of interest statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Figures

Fig. 1
Fig. 1
Graphic representation of the evolution of confirmed cases per day and the daily number of deaths by COVID-19 in Madrid. It also shows the cumulative absolute number of confirmed cases and deaths in the study period. Modified from (Dirección General de Salud Pública y Sanidad Mortuoria, 2020). Comunidad de Madrid. https://www.comunidad.madrid/servicios/salud/2019-nuevo-coronavirus.
Fig. 2
Fig. 2
a) Meteorology (Temperature, Precipitation, Wind speed, relative humidity) and b) particulate matter (PM10, PM2.5 and PM1) concentrations during April and May in Madrid. Natural processes like Saharan dust outbreaks and sampling periods are shown.
Fig. 3
Fig. 3
Map of the accumulated incidence rate in the last fourteen days in Madrid, highlighting the study district Moncloa-Aravaca a) number of confirmed cases per 100,000 inhabitants on 15/05/2020 and b) incidence rate on 31/05/2020. Modified from (Red de Vigilancia Epidemiológica de la Comunidad de Madrid, 2021). Consejería de Sanidad. Comunidad de Madrid. https://www.comunidad.madrid/servicios/salud/2019-nuevo-coronavirus. (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)
See this image and copyright information in PMC

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