How much does the SARS-CoV-2 virus really spread in the air? In which environments does it proliferate most? Piedmont harp published, already in January, an important research able to shed light on questions that have been the subject of scientific debate for some time. What emerges is that the lockdown method, with closures and limitations even in being outdoors, could in fact have exacerbated the circulation of the virus leading to an increase in contagion in our country.
The Regional Agency for Environmental Protection has a reproducible and validable method to determine the presence of the virus in the air, both indoors and outdoors. As explained by the General Manager of Arpa Piemonte Angelo Robotto: “In view of the lack of standardization, the validation of a new method of sampling and analysis of the environmental matrices involved in the spread of the virus is a complex job. Complex but at the same time absolutely essential to provide reliable and safe data to the competent bodies in the management of the health risk of the population. It is a work that can only be successfully completed through a multidisciplinary approach that goes from chemistry to biology, to physics, with the use of diversified technologies depending on the environmental matrix and the purpose of the research. A multidisciplinary characteristic of the Environmental Agencies, thanks to the different professionals, different studies, different areas that collaborate to achieve common goals “.
The sampling techniques developed involve the use of the following systems:
- a centrifugal impactor capable of accelerating the flow of aspirated air to the speed of sound, minimizing evaporative losses, maintaining the infectivity and integrity of the viral particles by transferring them directly to a suitable transport solution;
- a low volume sampler for air filtration on PTFE filters, a material that guarantees the maximum capture capacity of viral particles ranging in size from 10 to 900 nanometers;
- a high volume sampler for air filtration on glass fiber or quartz filters, capable of aspirating the entire volume of a room in less than an hour.
For each of these techniques, the close collaboration between Arpa Piemonte and the Laboratory of Molecular Virology and Antiviral Research of the San Luigi Gonzaga University Center in Orbassano (TO) has allowed the development of desorption, concentration for ultracentrifugation and transport protocols of viral particles specific for this type of environmental sampling.
The Arpa Piemonte Regional Center for Molecular Biology in La Loggia (TO), whose main activity is focused on the analysis of molecular swabs for the diagnosis of Covid-19, has also developed a analytical method that can be applied to the analysis of environmental samples optimizing the viral nucleic acid recovery and extraction step and the molecular amplification step of viral genome fragments by means of the RT-PCR technique.
The field tests of the techniques developed involved hospital departments specialized in the treatment of COVID patients, the interiors of the homes of infected families, the air outside the COVID departments of hospitals as well as the breathable air in any street in the center of the capital. regional.
The results obtained with a quantifiable degree of certainty support the following considerations:
- in the external environment, the virus has not so far been detectable in the air;
- in hospitals, and in particular in wards with the presence of patients also characterized by high viral loads, the detectable concentrations of SARS-CoV-2 were generally very low, also by virtue of the high rate of air exchange made in these areas (6-8 air changes per hour);
- in the domestic environment, on the contrary, virus concentrations were found to be more consistent, up to 40 ÷ 50 genomic copies of the virus per cubic meter of air. These values are strongly influenced by the air exchange frequencies and by the number of positive subjects present in the homes, as well as by the development of the most common symptoms of the disease (dry cough).
The results thus briefly described confirm those reported by some studies published in a scientific journal in the spring of 2020, even though these results were not then supported by the use of validated analytical methods such as those being perfected by the Agency.
The ability to sample gasses in order to reliably determine the presence of SARS-CoV-2 and other airborne pathogens in the air matrix proves to be essential for the development, during the pandemic, of a coherent management of places, in particular crowded places such as means of transport, stations, gyms, theaters, cinemas. In this regard, the studies described here provide a solid basis for developing reliable methods for quantifying the viral load in the air, allowing, in perspective, to assess the degree of risk of contagion in a specific environment. They also represent an important acquisition of technical knowledge that can be readily applied in the future in the event of the emergence of new epidemics or pandemics.
Further developments in the field of Environmental Virology concern the techniques of desorption from quartz filters for a greater depth of the quality of the air monitored in the control units of the Agency, the validation of the analysis method on wastewater for epidemiological surveillance purposes, currently in course, the development of virus cultivation activities, a very delicate step also in terms of safety.
This is what we read in Arpa’s study. Summing up, therefore, staying closed at home for months, as happened during the 2020 lockdown and as it still happens now when the measures in the red zone are tightened, is deleterious. It is a mechanism that, far from making the virus circulate less, makes it proliferate inside our homes. And on the other hand, it is since the days of the Conte government that they ‘advise’ us not to gather in private homes, but at the same time Italians have been imposed on outdoor masks and other restrictions – see concerts and outdoor events prohibited for months – absolutely useless in the light of what emerged from the meticulous research of Arpa Piemonte.
Perhaps it would have been more useful, together with the advice not to gather at home, invite us to be outdoors as much as possible, from January 2020 to now. And instead we all remember citizens, alone on the beach, hunted and chased by the police because they had to stay indoors and not walking in the open air.
On an empty beach.