Role of the chronic air pollution levels in the Covid-19 outbreak risk in Italy

Abstract

After the initial outbreak in China, the diffusion in Italy of SARS-CoV-2 is exhibiting a clear regional trend with more elevated frequency and severity of cases in Northern areas. Among multiple factors possibly involved in such geographical differences, a role has been hypothesized for atmospheric pollution. We provide additional evidence on the possible influence of air quality, particularly in terms of chronicity of exposure on the spread viral infection in Italian regions. Actual data on Covid-19 outbreak in Italian provinces and corresponding long-term air quality evaluations, were obtained from Italian and European agencies, elaborated and tested for possible interactions. Our elaborations reveal that, beside concentrations, the chronicity of exposure may influence the anomalous variability of SARS-CoV-2 in Italy. Data on distribution of atmospheric pollutants (NO₂, O₃, PM_2.5 and PM₁₀) in Italian regions during the last 4 years, days exceeding regulatory limits, and years of the last decade (2010-2019) in which the limits have been exceeded for at least 35 days, highlight that Northern Italy has been constantly exposed to chronic air pollution. Long-term air-quality data significantly correlated with cases of Covid-19 in up to 71 Italian provinces (updated April 27, 2020) providing further evidence that chronic exposure to atmospheric contamination may represent a favourable context for the spread of the virus. Pro-inflammatory responses and high incidence of respiratory and cardiac affections are well known, while the capability of this coronavirus to bind particulate matters remains to be established. Atmospheric and environmental pollution should be considered as part of an integrated approach for sustainable development, human health protection and prevention of epidemic spreads but in a long-term and chronic perspective, since adoption of mitigation actions during a viral outbreak could be of limited utility.

Keywords: Atmospheric pollution; Chronic exposure; Covid-19; Italy; Viral diffusion.

Graphical abstract

Fig. 1

Regional distribution of Covid-19 outbreak in Italy (from February 24 to April 27, 2020). A) abundance of Covid-19 cases (absolute number); B) percentage of positive subjects referred to the number of performed tests (oropharyngeal swabs); C) mortality rate on the number of positive cases; D) percentage of Covid-19 cases normalized to the number of inhabitants; E) percentage of deaths normalized to the number of inhabitants. Data obtained and re-elaborated from the official daily reports of Italian Civil Protection Department (ICPD, 2020).

Fig. 2

Regional data on air quality levels: A) nitrogen dioxide (NO₂); B) particulate matter of 2.5 μm or less (PM_2.5); C) particulate matter of 2.5–10 μm (PM₁₀). Data are referred to the means of values of last four years (2016–2019), expressed as μg/m³ (obtained and elaborated from the European Environmental Agency, accessed on 6 April, EEA, 2020).

Fig. 3

Number of days per year exceeding the regulatory limits relating to A) ozone (O₃) and to B) particulate matter (PM₁₀), as average means of the last 3 years (2017–2019); C) number of years in which the PM₁₀ limit was exceeded for at least 35 days per year, from 2010 to 2019. Data are obtained and elaborated from annual reports (Legambiente, 2018, 2019; 2020) and referred to the official statistics of the European Environmental Agency (EEA, 2019).

Fig. 4

Statistical correlation between the regional distribution of COVID-19 cases and the air quality parameters in Italy: incidence of Covid-19 cases vs levels of A) NO₂, B) PM_2.5 and C) PM₁₀ (four years means); incidence of Covid-19 cases vs number of days per year exceeding regulatory limits of D) O₃ and E) PM₁₀ (three years means). Data obtained and elaborated from EEA (2019; , ICPD (2020), and Legambiente (2018, 2019; 2020).