Coronavirus: How particulates accelerated the spread in northern Italy

Atmospheric particulatesis suitable as a transport carrier for many chemical and biological contaminants - especially viruses.viruses - like the coronavirus - dock onto atmospheric particles (solid and/or liquid). These remain in the atmosphere for hours, days or weeks. In this way, a virus can spread even over great distances. The researchers from Italy speak of air pollution being a kind of highway for the coronavirus.

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Scientific studies on the spread of viruses in the population show: The frequency (incidence) of viral infections correlates with concentrations of atmospheric particulates(e.g. PM10, PM2.5). In 2016, for example, a correlation was observed between the spread of the syncytial virus (RS virus) in children and the concentration of particulate matter. This virus causes pneumonia in children and is transported deep into the lungs by particles. The rate of spread of infection is related to PM10 and PM2.5 concentrations.

particulates acts as a carrier - and as a substrate

But particulates particles not only have a carrier function, but also serve as a substrate that allows the virus to remain viable in the air for hours or days. The rate at which many viruses become inactive in these particles depends significantly on the environmental conditions: while an increase in temperature and solar radiation have a positive effect on the virus inactivation rate, high relative humidity can promote a higher rate of virus spread, i.e. virulence.

This general connection between air pollution from particulatesand the spread of viruses, such as the coronavirus, is now confirmed by the findings of researchers from the Italian Society for Environmental Medicine (Sima) together with the Universities of Bari and Bologna.

The researchers compared the regional environmental protection authorities' data on the exceedance of the legal limits for particulates (50 micrograms per cubic metre average daily concentration, more on particulates as a limit in Germany) with the reported cases of infection with the coronavirus reported by the civil protection authorities.

Analysis of coronavirus spread

The analysis showed a relationship between the exceedances of the legal limits for PM10 concentrations detected in the period between 10 and 29 February and the number of cases infected with COVID-19 updated to 3 March (taking into account an incubation period of 14 days).

"The more particulates particles there are, the more highways are created for contagion. It is necessary to reduce emissions to a minimum in the hope of favourable meteorology." (Gianluigi de Gennaro, University of Bari)

According to the researchers, there was an "anomalous acceleration" particularly in the Po Valley in northern Italy, which coincided with the highest concentrations of atmospheric particles two weeks later. Thus, the particles exerted a kind of buoyancy effect, an impulse for the virulent spread of the epidemic.

"The high dust concentrations detected in the Po Valley in February caused an acceleration of the spread of Covid-19, and the effect is more noticeable in the provinces where the first outbreaks occurred". (Leonardo Setti of the University of Bologna)

First, the scientists have now published a position paper to present their hypothesis. The next step is now to consolidate the evidence in a broader study. "Until then, the concentration of particulatescould definitely be considered as a possible indicator or indirect marker for the virulence of the Covid 19 epidemic. Moreover, according to the results of the ongoing study, the current safety margin during the Corona epidemic may not be sufficient everywhere, especially at high concentrations of atmospheric particulate matter," says Allesandro Miani, President of Sima.

According to the researchers, it is important to actively improve the air quality at home during times of quarantine and curfews. Miani recommends opening the windows for a few minutes several times a day because mixing gas reduces the percentage of pollution. Air purifiers can also help decisively. Also advisable: avoid activities that produce particulates (driving, smoking, barbecuing, etc). Especially in narrow neighbourhood streets, existing particulates can be a multiplier of the infection and increase the risk of infection.

The position paper is available for download here. And in this post we looked at the question of whether air pollution increases the COVID-19 death rate.

Further sources:

(1) Ciencewicki J et al, 2007. "Air Pollution and Respiratory Viral Infection" Inhalation Toxicology, 19: 1135-1146.

(2) Sedlmaier N., et al., 2009 "Generation of avian influenza virus (AIV) contaminated fecal fine particulate matter (PM2.5): Genome and infectivity detection and calculation of immission" Veterinary Microbiology 139, 156-164

(3) Ye Q., et al., 2016 "Haze is a risk factor contributing to the rapid spread of respiratory syncytial virus in children" Environ Science and Pollution Research, 23, 20178-20185

(Image: Unsplash / Bjorn Snelders)