A review on measurements of SARS-CoV-2 genetic material in air in outdoor and indoor environments: Implication for airborne transmission.

The Impact of COVID-19 on Urban Energy Consumption of the Commercial Tourism City

Role of atmospheric particulate matter exposure in COVID-19 and other health risks in human: A review.

Viral outbreaks detection and surveillance using wastewater-based epidemiology, viral air sampling, and machine learning techniques: A comprehensive review and outlook.

COVID-19 pandemic raised a debate regarding the role of airborne transmission. Information regarding virus-laden aerosol concentrations is still scarce in community indoors and what are the risks for general public and the efficiency of restriction policies. This work investigates, for the first time in Italy, the presence of SARS-CoV-2 RNA in air samples collected in different community indoors (one train station, two food markets, one canteen, one shopping centre, one hair salon, and one pharmacy) in three Italian cities: metropolitan city of Venice (NE of Italy), Bologna (central Italy), and Lecce (SE of Italy). Air samples were collected during the maximum spread of the second wave of pandemic in Italy (November and December 2020). All collected samples tested negative for the presence of SARS-CoV-2, using both real-time RT-PCR and ddPCR, and no significant differences were observed comparing samples taken with and without customers. Modelling average concentrations, using influx of customers' data and local epidemiological information, indicated low values (i.e. < 0.8 copies m-3 when cotton facemasks are used and even lower for surgical facemasks). The results, even if with some limitations, suggest that the restrictive policies enforced could effectively reduce the risk of airborne transmissions in the community indoor investigated, providing that physical distance is respected.

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Airborne concentrations of SARS-CoV-2 in indoor community environments in Italy.

The question of how SARS-CoV-2 is transmitted remains surprisingly controversial today, especially with reference to airborne transmission. In fact, despite a large body of scientific evidence, health and regulatory authorities still require direct proof of this mode of transmission. To close this gap, we measured the saliva viral load of SARS-CoV-2 of an infected subject located in a hospital room, as well as the airborne SARS-CoV-2 concentration in the room resulting from the person breathing and speaking. As the next step, we simulated the same scenarios to estimate the concentration of RNA copies in the air through a novel predictive theoretical approach. Finally, we conducted a comparative analysis (i.e. a metrological compatibility analysis) of the differences between the experimental and theoretical results by estimating the uncertainties of these two approaches. Our results showed that for an infected subject's saliva load ranging between 2.4x106 and 5.5x106 RNA copies mL-1, the corresponding airborne SARS-CoV-2 concentration was not detectable when the person was breathing, but was 16.1 (with an uncertainty of 32.8) RNA copies m-3 when speaking. The application of the novel predictive estimation approach provided average concentrations of 3.2 (uncertainty range of 0.2-8.3) and 18.5 (uncertainty range of 4.5-43.0) RNA copies m-3 for breathing and speaking scenarios, respectively, thus confirming that for the breathing scenario, the airborne RNA concentration would be undetectable, being below the minimum detection threshold of the experimental apparatus (< 2 RNA copies m-3).

Link between SARS-CoV-2 emissions and airborne concentrations: closing the gap in understanding

SARS-CoV-2 and indoor/outdoor air samples: a methodological approach to have consistent and comparable results.

SARS-CoV-2 airborne transmission: A validated sampling and analytical method.

The experience gained over the last hundred years clearly indicates that two groups of viruses represent the main risk for the development of highly transmissible epidemics and pandemics in the human species: influenza viruses and coronaviruses (CoV). Although the search for viruses with pandemic potential in the environment may have an important predictive and monitoring role, it is still based on empirical methodologies, mostly resulting from the clinic and not fully validated for environmental matrices. As far as the SARS-CoV-2 pandemic, currently underway, is concerned, environmental monitoring activities aiming at checking the presence of SARS-CoV-2 in wastewater can be extremely useful to predict and check the diffusion of the disease. For this reason, the present study aims at evaluating the SARS-CoV-2 diffusion by means of a wastewater-based environmental monitoring developed in Piedmont, N-W Italy, during the second and third pandemic waves. Wastewater sampling strategies, sampling points sample pre-treatments and analytical methods, data processing and standardization, have been developed and discussed to give representative and reliable results. The following outcomes has been highlighted by the present study: i) a strong correlation between SARS-CoV-2 concentration in untreated wastewater and epidemic evolution in the considered areas can be observed as well as a predictive potential that could provide decision-makers with indications to implement effective policies, to mitigate the effects of the ongoing pandemic and to prepare response plans for future pandemics that could certainly arise in the decades to come; ii) moreover, the data at disposal from our monitoring campaign (almost 500 samples analysed in 11 months) confirm that SARS-CoV-2 concentrations in wastewater are strongly variable and site-specific across the region: the highest SARS-CoV-2 concentration values have been found in sewer networks serving the most populated areas of the region; iii) normalization of viral concentrations in wastewater through Pepper Mild Mottle Virus (a specific faecal marker) has been carried out and commented; iv) the study highlights the potential of wastewater treatment plants to degrade the genetic material referable to SARS-CoV-2 as well. In conclusion, the preliminary data reported in the present paper, although they need to be complemented by further studies considering also other geographical regions, are very promising.

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Angelo Robotto

Papers

Link between SARS-CoV-2 emissions and airborne concentrations: closing the gap in understanding

SARS-CoV-2 and indoor/outdoor air samples: a methodological approach to have consistent and comparable results.

SARS-CoV-2 airborne transmission: A validated sampling and analytical method.

Wastewater-based SARS-CoV-2 Environmental Monitoring for Piedmont, Italy

Wastewater-based SARS-CoV-2 environmental monitoring for Piedmont, Italy.