A research from University of Bari has finally scientifically proved what we all feared: air pollution actually increases the risk of mortality from Covid-19.

The study by researchers from the University of Bari, coordinated by Prof. Piero Portincasa, published in the scientific journal Environmental Science and Pollution Research, helps to clarify the complex mechanisms that determine the risk of death in patients affected by COVID-19.

The original title of the paper is “Nitrogen dioxide pollution increases vulnerability to COVID-19 through altered immune function” and the authors are Agostino Di Ciaula, Leonilde Bonfrate, Piero Portincasa and the IMC-19, the large group of doctors of the Medical Clinic “A. Murri” and of the Internal Medicine Hospital of the Policlinico di Bari engaged in the COVID-19 front since the first wave of the pandemic in 2020 and currently involved also in the management of patients with post-COVID and non-COVID pathologies.


The subjects

The study was carried out on 147 patients in the period before the vaccination campaign.
The 147 patients (mean age 66.8 ± 1.3 years, age range 31–99 years, 93 males) originating from 10 cities in Apulia (Southern Italy) including Bari and its Province, were admitted to the COVID-unit of internal medicine “A. Murri” of the large Regional Hospital Policlinico of Bari, from March 2020 to April 2021 due to acute SARS-CoV2 infection with pneumonia.
Patients were laboratory confirmed to be SARS-CoV-2 infected by real-time RT-PCR (nasopharyngeal swab). Data for each individual was collected by medical personnel. All patients underwent a full clinical assessment and blood sampling with a count of white blood cells the same day of hospital admission. Inclusion criteria were (a) diagnosis of acute pneumonia, defined as pulmonary infiltration (CT confirmation); (b) no need for admission to intensive care unit; (c) availability of a valid pre-hospitalization address, and (d) living in the 2 weeks before hospitalization in an urban area where air monitoring stations were present and active.


Illuminating results

The research shows for the first time directly that, independently of the already known risk factors for mortality from COVID (old age and chronic diseases), patients hospitalised for COVID have an unfavourable risk of clinical development influenced by previous and recent exposure to nitrogen dioxide (NO2). This air pollutant is extremely widespread and is mainly produced in urban areas by vehicle traffic and fossil-fuelled domestic heating.
“The research – explains the study’s first author Dr. Agostino Di Ciaula – shows that the air pollution to which one is exposed before contracting the SARS-COV-2 viral infection plays a major role in producing immune alterations that can promote viral infection and affect the risk of death in patients who are subsequently hospitalised, especially if they are frail”.
This publication”, explains Prof. Piero Portincasa, Professor at the University of Bari and Director of the “A. Murri” Medical Clinic at the Bari General Hospital, “directly confirms in patients what numerous ecological studies had previously indirectly suggested, i.e. that the quality of the urban environment is able to influence COVID-19 disease and that primary prevention measures could significantly reduce the severity of the infection, especially in at-risk individuals”.



Tim Hornyak reports how Heather Walton, a senior lecturer in environmental health at Imperial College London who was not involved in the study, said that although the statistical analysis needs to be confirmed, the findings add to existing knowledge.
There are only a few studies that have individual data available. There have already been other studies on long-term exposure to air pollution and hospital admissions that had individual data, but, at least until May 2021https://eos.org/articles/exposure-to-low-levels-of-air-pollution-increases-covid-19-risk… there was not one like this on incidence of infection. However, this is subject to whether the statistical analysis is appropriate,” said Walton, who coauthored an Imperial College review on pollutants and COVID-19. “The hypotheses addressed are familiar ones. Nonetheless, if the statistics check out, then it is good to have additional evidence on the hypotheses.”

Corresponding author Giovanni Veronesi, a professor at the Research Center in Epidemiology and Preventive Medicine, Department of Medicine and Surgery, at the University of Insubria in Italy, noted that more research is required to establish a causal link between air pollution and COVID-19 susceptibility. He and his collaborators are working to expand the study to cover more people, a longer period, nonurban settings, and broader COVID-19 end points, such as hospitalizations and deaths.

“If SARS-CoV-2 is to become endemic in a population, our results imply that this will be an additional health threat to people already suffering higher respiratory and cardiovascular disease rates due to air pollution exposure,” Veronesi said. “Therefore, governments should implement their efforts to reduce air pollution levels as a measure to mitigate the public health burden of COVID-19, with no further delays”.

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