The virus moves with people, not with smog: the particulate matter present in the polluted air does not carry viral particles capable of spreading the infection, for which the frequency and proximity of contacts are directly responsible. Smog could play a role in the course of the disease in those who have been infected: those who have been exposed to pollution are more fragile compared to the virus and therefore have a greater risk of encountering more serious consequences in the case of Covid-19.
The smog does not 'carry' SARS-Cov-2 but those who have long been exposed to polluted air, if infected, could face a more serious disease. The top international experts who confronted each other during the International Webinar "Air pollution and Covid-19: mechanisms, preliminary findings and ways ahead", organized by the Menarini International Foundation as part of the RespiraMi project, support it: according to the data of the studies available at today, polluting particles cannot act as 'transporters' of virus infectious particles and air pollution is therefore hardly responsible for a surge in infections, but exposure to smog can have negative effects on general health, making it more fragile in the face of the virus and increasing the prevalence of cardiovascular, metabolic and respiratory diseases in the population, thus increasing the share of subjects with a higher risk of worse consequences in case of contagion from Covid-19. International research is unable to demonstrate a cause-effect relationship between smog and infections. It is increasingly evident, however, that smog is a "third uncomfortable" between the virus and the body: when the body is more compromised, the damage is greater.
“SARS-Cov-2 is transmitted mainly through the respiratory droplets, or droplets, of an infected person who coughs, sneezes or speaks at close range; Contagion from infected surfaces is rarer, while some indications suggest that the virus may remain infectious in the aerosol of a closed environment - notes Sergio Harari, co-president of the Seminar and Director of the Pneumology Operating Unit, San Giuseppe Hospital in Milan - Instead, the hypothesis that atmospheric particulate matter can 'transport' the virus and therefore help spread it by air does not seem plausible: the particulate matter can carry biological particles such as bacteria, spores, pollen and even viruses, but it seems unlikely that Coronaviruses can keep intact morphological characteristics and infectious properties after a more or less prolonged stay outside because temperature, drying and UV rays damage the envelope of the virus and therefore its ability to infect. Therefore a link between the daily fluctuations of the particulate matter and the incidence of Coronavirus infections is not confirmed or plausible to date ".
The hypothesis that pollution could be directly responsible for an increase in the probability of infection derives from the spread of Covid-19 in the Po Valley, one of the most polluted areas in Europe; however scientific studies seem to indicate with certainty that the epidemic moves with people, not through smog. "For an epidemic with respiratory infection, the main determinant of the spread is the frequency and proximity of contacts between people - intervenes Pier Mannuccio Mannucci, co-president of the Seminar and Emeritus Professor of Medicine, Internal University of Milan - The Po Valley is one of the most industrialized areas of the country, with a high number of international contacts, and this together with the high population density can be considered the major determinant of the surge in the contagions in the past months. The drastic drop in infections following the lockdown and social distancing also suggests that particulate matter is not decisive in the transmission of the virus, because it remains in the air for weeks and can be distributed for kilometers horizontally. Instead, it is known that environmental pollution increases the probability of cardiovascular, metabolic and lung diseases: therefore, in the most polluted areas, the share of the population at high risk of developing complications from Covid-19 is greater ".
Furthermore, polluting particulate matter leads to an increase in the inflammatory response at the lung level and this, in the presence of SARS-Cov-2, could favor the appearance of more serious symptoms. "By analogy with what is observed for other diseases, it is possible that with higher environmental pollution levels, those who have been infected with SARS-Cov-2 are more susceptible to a clinically relevant progression than Covid-19 - adds Francesco Forastiere, epidemiologist, co -president of the seminar, and director of the journal Epidemiology and Prevention. However, to date we do not have enough data to be sure of the impact of air pollution on the short and long-term course of SARS-Cov-2 infection: to arrive at conclusive data, rigorous epidemiological studies will be needed, with adequate collection of clinical and environmental data on an individual basis which is as homogeneous as possible throughout the national territory in order to study the possible associations between pollution and diffusion and gravity of Covid-19 ".