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The links emerging between the Covid-19 mortality rate and PM2.5 pollution should come as no surprise. For the lethal effects of particulate matter pollution have been scientifically accepted knowledge for a considerable amount of time. The WHO estimated that in 2016 particulate matter pollution led to 4.2 million premature deaths around the globe. But decisive action to combat the threat has failed to be taken up on a widespread scale, and the public awareness has failed to gain the sufficient mass to force change.

The Coronavirus crisis, however, has brought the issue into distinct focus. Its ability to spread itself through the air has made us all more aware of the air we breathe, and its attacking of the respiratory system made shared the concerns which were formerly only the preserve of the informed few. In particular, many new scientific studies are now coming out from across the globe which are linking the quality of an area’s air to the Covid-19 mortality rate. We report below on some of the latest findings.

Covid-19 mortality and particulate matter pollution

Scientific studies are now coming out from across the globe which are linking the quality of an area’s air to the amount of deaths Covid-19 will inflict. An as of yet unpublished study undertaken by the Department of Biostatistics at the Harvard T.H Chan School of Public Health points to the statistical correlation between the levels of PM2.5 pollution in an area and the deaths related to Covid-19 in that area.

The study was a national one encompassing data from more than 3,000 counties in the US. This means that the data in effect covers 98% of the nation’s inhabitants. It was found that, on average, just a 1μm/m3 increase in a county’s PM2.5 concentration translated statistically into an 8% increase in the mortality rate. Put simply, if you live in an area with higher levels of fine dust, and you contract SARS-CoV-2, you are more likely to die than if you lived in an area with less fine dust.

Another study from the University of Siena, also not having yet undergone peer-review, postulated the mechanism which would lead to this statistical correlation. Motivated by data coming out of northern Italy, where the mortality rate of Covid-19 was in the virus’ onset anomalously high, they remarked upon the first stage of Covid-19’s lethal progression: the inflammation of the upper airways. If your upper airways are inflamed, it means that the upper airways’ defences, such as the cilia or mucus, have been overwhelmed, leaving the penetration of the virus to the lower airways much more likely. (Read more on the respiratory system’s defences here.)

This inflammation is the very effect that long-term exposure to high levels of PM2.5 has been found to have. If your upper airways are already inflamed from PM2.5 exposure, and your defences therefore dysfunctional, it is then all the more likely that the virus will enter into your lower airways and lungs. This is where the virus is most lethal.

This postulated causal link was then grounded in the fact that the air quality of northern Italy’s affected regions is some of the worst in Europe, with particulate matter rates regularly exceeding the EU guidelines. This naturally led the scientists to form the following conclusion: the reason for the higher mortality rates in the northern parts of Italy was their higher rates of particulate matter pollution, and the already weakened populace. The constant exposure of Northern italians in the Po Valley to high levels of airborne PM2.5 made them on average more likely to pass away if they contracted Covid-19.

po valley worst fine dust rate in europe map
The Po Valley region in Italy had in 2016 one of the worst PM2.5 annual mean values in Europe, as this map compiled by the European Environment Agency depicts.

The message is clear. Particulate matter pollution kills, be it from an increased likelihood of lung cancer, an increased threat of cardio-pulmonary illnesses, or from the weakening of one’s defences against respiratory infections, such as Covid-19. To reduce the former, constant threats, but also to prevent the re-occurence of a catastrophe such as the latter, effective dust control measures must be put in place.


Can atmospheric pollution be considered a co-factor in extremely high level of SARS-CoV-2 lethality in Northern Italy? Edoardo Conticini, Bruno Frediania, Dario Caro.  Available at:

Wu, X et al., (2020). Exposure to air pollution and COVID-19 mortality in the United States. [Pre-print]. Available at: