Virus on the air

Publish date 20-05-2020

by Pierluigi Conzo

Also the pollution among the spreading factors of Covid. The results of a research.


The unequal geographical distribution of the virus in Italy makes you think. Considering that, as some authors claim, the virus circulated in Italy well before the first cases were discovered, why did COVID-19 spread mainly in some northern provinces? Yet high-speed trains and planes connect the peninsula in a short time: endless flows of commuters or travelers move - better, they move - every day between the Italian provinces. In a research conducted with colleagues L. Becchetti and G. Conzo of the University of Rome "Tor Vergata" and F. Salustri of the University of Oxford, I tried to analyze some factors that, based on previous studies, may have played an important role for the heterogeneous spread of the virus in the country.


The main factors we analyze - prior to the advent of the virus - are, for the moment, five. First of all, there are many medical studies that demonstrate the existence of a strong correlation between air quality, and in particular the presence of pollution in the form of particulates. According to these studies, prolonged exposure to polluting agents weakens the alveoli and lungs, making people more vulnerable to inflammation of the respiratory system and pneumonia. Covid-19 seems to manifest itself in these ways. Therefore more polluted areas, such as some provinces of the Po Valley, north-west and north-east, could have more easily hosted the virus. A study carried out by colleagues from Harvard on about 6000 counties in the United States, just before ours, found a positive and significant association between previous exposure to fine particles, contagions and deaths from coronaviruses.


The second factor we analyze, again on the basis of previous studies, is the temperature: it seems that the virus prefers warmer and more humid areas. Descriptive data seem to support this hypothesis if we look at the north-south divide in Italy and that between Madrid and other regions of Spain; similarly according to the WHO, as of March 27, 2020, the country in Africa with the highest number of infections is South Africa (with Mediterranean climate), followed by Algeria, while in other countries there are only a few cases of imported transmission.

The third factor is the presence of artisan businesses in the area. Small business employers and entrepreneurs live in a very competitive environment with reduced social protection. In most cases they are suppliers of large companies and often have little negotiating power in the supply chain, which translates into worse conditions of commercial credit. Furthermore, micro and craft enterprises are in a higher proportion in the manufacturing sector, with fewer opportunities to convert their activities into smart working. Small businesses may have a relatively lower propensity to stop during the epidemic, precisely because of the greater risk of adverse economic consequences. In addition, provinces with a particularly vibrant economic environment also experience more social transactions and interactions. Both of these factors may be related to a greater spread of the virus.


The fourth pre-existing factor to the virus that we take into consideration concerns mobility and density since these provincial characteristics can increase the chances of social interaction and therefore the spread of the virus.

Finally, we consider the demographic structure of the virus by including the percentage of residents over the age of 65 in the analysis, as this age group has been shown to be more vulnerable to the virus. Among other provincial demographic characteristics, we also decided to study whether the presence of the Chinese community in Italy can be associated with the spread and mortality of the virus. Provinces with a greater presence of Chinese may also have had more socio-economic exchanges with China before the outbreak of the virus. Regardless of the veracity of this hypothesis, the fact is that the Chinese in Italy were often subjected to discrimination during the first days of the Covid-19 epidemic, in the form of physical and verbal violence (even by some political exponents). Our study aims to study the relative importance of these factors in terms of virus spread (positive cases, Civil Protection data) and mortality (ISTAT data). Furthermore, as a preliminary, we also assessed whether the lockdowns decided first autonomously by the provinces and then at central level played a role in the spread of the virus.


Before describing the results, it is necessary to clarify that what our statistical analysis highlights are correlations between phenomena, for example air quality and virus spread. At this stage, we are not yet able to establish a causal link that goes from one to the other; also there are many issues related to possible measurement errors in the contagion and mortality variables we use.

However, the preliminary results show that the factors that play an important role are mainly the quality of the air and the presence of artisan businesses. The virus seems to spread faster and make more victims in provinces with relatively high values ​​of PM10 and PM2.5 and with little urban green per inhabitant, therefore confirming the hypothesis of a possible link between previous exposure to pollution and vulnerability to the virus. Furthermore, the virus seems to have found fertile ground in provinces with a higher concentration of micro-enterprises and artisan enterprises, probably due to the greater human activity linked to these activities and to the fact that the latter are difficult to convert into smart work. Furthermore, we find a negative correlation between lockdown decisions spreading the virus: if this correlation also implied a causal link, the results would suggest that the lockdown seems to have been effective in reducing the contagion, even if at 6 April 2020 it still does not seem to have had effects on mortality.


If the observed correlations were causally interpretable, which we are working on, there would be good news: we can do something to build societies more resilient to pandemic shocks of this type. Such as? If we look at fine particles, at a regional level, these are mostly produced by domestic heating, followed by intensive farming, transport and industrial production. It is therefore necessary to put the environment and the well-being of the community at the center of the restart, for example by rewarding companies in the most affected areas that make "green" investments, stimulating sustainable mobility and energy efficiency, by encouraging smart working alongside policies for the reduction of the technological gap and for work-family reconciliation. And above all it must be done immediately: the well-being of people cannot be postponed to a phase 3, 4, or 5.


See the focus Reflections in Time of Covid 19

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