COVID-19 – REPORT: ranking of European cities with the highest mortality rates from air pollutants

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A health impact study has for the first time estimated the mortality burden attributable to air pollution in more than 1,000 European cities.

The study, published in The Lancet Planetary Health, includes a ranking of the European cities with the highest rates of mortality attributable to each of the two air pollutants studied: fine particulate matter (PM2.5) and nitrogen dioxide (NO2).

The research project was led by the Barcelona Institute for Global Health (ISGlobal), in collaboration with researchers from the Swiss Tropical and Public Health Institute (Swiss TPH) and Utrecht University.

The findings show that 51,000 and 900 premature deaths could be prevented each year, respectively, if all the cities analyzed were to achieve the PM2.5 and NO2 levels recommended by the World Health Organization (WHO).

However, if all of the cities were to match the air-quality levels of the least polluted city on the list, even more deaths could be prevented. Specifically, the number of premature deaths that could be prevented each year by reducing PM2.5 and NO2 concentrations to the lowest measured levels are 125,000 and 79,000, respectively.

Mortality rankings

After estimating the preventable premature deaths in each city, the research team ranked the cities by mortality burden for each of the two pollutants studied.

“We observed great variability in the results for the different cities analyzed,” commented ISGlobal researcher Sasha Khomenko, lead author of the study. “The highest rates of mortality attributable to NO2, a toxic gas associated primarily with motor-vehicle traffic, were found in large cities in countries such as Spain, Belgium, Italy and France.”

“For PM2.5, the cities with the highest mortality burden were in Italy’s Po Valley, southern Poland and the eastern Czech Republic. This is because suspended particulate matter is emitted not only by motor vehicles but also by other sources of combustion, including industry, household heating, and the burning of coal and wood,” added Khomenko.

“The highest percentage of natural mortality that could be attributed to fine particulate matter was 15%, in the city of Brescia. With regard to nitrogen dioxide, the highest percentage – up to 7% of natural mortality— –

At the opposite end of the ranking are the cities with the lowest rates of mortality attributable to air pollution, a privileged position occupied by northern European cities in both the PM2.5 and NO2 rankings.

“This is the first study to estimate the mortality burden attributable to air pollution at the city level in Europe,” commented Mark Nieuwenhuijsen, senior author of the study and Director of the Urban Planning, Environment and Health Initiative at ISGlobal, a center supported by the “la Caixa” Foundation.

“Our findings support the evidence suggesting that there is no safe exposure threshold below which air pollution is harmless to health. They also suggest that the European legislation currently in force does not do enough to protect people’s health. Therefore, the maximum NO2 and PM2.5 levels allowed by law should be revised.

We hope that local authorities can use these data to implement urban and transport planning policies aimed at improving people’s health.”

Online Data Hub

This study forms part of the ISGlobal Ranking of Cities project and is the first in a series of analyses of the health impacts of various environmental factors inherent to urban life, including air pollution, noise, access to green spaces, heat island effects, etc.

The website http://www.isglobalranking.org has been created as a hub for the rankings and detailed data on each city. The site is currently available in English, Spanish and Catalan. Data from the project’s other analyses and rankings will be added to the site as they become available.

Methodology

The study followed the quantitative health impact assessment methodology, which compares current levels of air pollution in cities with two counterfactual scenarios with improved air quality. Relying on recent scientific evidence on the relationship between air pollution levels and mortality, the researchers calculated the impact that both air-pollution reduction scenarios would have on the mortality burden. Three mathematical models were combined to determine the average levels of each pollutant in each city, taking values from 2015 as a baseline and comparing them to data from 2018.

To perform city comparisons, the researchers assigned a mortality burden score to each city. The scores were calculated using an algorithm that took into account mortality rates, percentage of preventable annual premature deaths and years of life lost for each air pollutant.

Top 10 cities with the highest mortality burden

The ten cities with the highest mortality burden attributable to PM2.5:

  • 1. Brescia (Italy)
  • 2. Bergamo (Italy)
  • 3. Karviná (Czech Republic)
  • 4. Vicenza (Italy)
  • 5. Silesian Metropolis (Poland)
  • 6. Ostrava (Czech Republic)
  • 7. Jastrzebie-Zdrój (Poland)
  • 8. Saronno (Italy)
  • 9. Rybnik (Poland)
  • 10. Havírov (Czech Republic)

The ten cities with the highest mortality burden attributable to NO2:

  • 1. Madrid (metropolitan area) (Spain)
  • 2. Antwerp (Belgium)
  • 3. Turin (Italy)
  • 4. Paris (metropolitan area) (France)
  • 5. Milan (metropolitan area) (Italy)
  • 6. Barcelona (metropolitan area) (Spain)
  • 7. Mollet del Vallès (Spain)
  • 8. Brussels (Belgium)
  • 9. Herne (Germany)
  • 10. Argenteuil-Bezons (France)

Top 10 cities with the lowest mortality burden

The ten cities with the lowest mortality burden attributable to PM2.5:

  • 1. Reykjavík (Iceland)
  • 2. Tromsø (Norway)
  • 3. Umeå (Sweden)
  • 4. Oulu (Finland)
  • 5. Jyväskylä (Finland)
  • 6. Uppsala (Sweden)
  • 7. Trondheim (Norway)
  • 8. Lahti (Finland)
  • 9. Örebro (Sweden)
  • 10. Tampere (Finland)

The ten cities with the lowest mortality burden attributable to NO2:

  • 1. Tromso (Norway)
  • 2. Umeå (Sweden)
  • 3. Oulu (Finland)
  • 4. Kristiansand (Norway)
  • 5. Pula (Croatia)
  • 6. Linköping (Sweden)
  • 7. Galway (Ireland)
  • 8. Jönköping (Sweden)
  • 9. Alytus (Lithuania)
  • 10. Trondheim (Norway)

The world is currently gripped in a planetary health crisis, expected to cause at least 4.2 million deaths this year; that of atmospheric pollution. Polluted air is the most significant environmental risk factor for all-cause mortality. It has increased the risk of cancer, chronic pulmonary and cardiovascular diseases, and caused the loss of at least 100 million disability-adjusted life-years (DALYs) and US$225 billion annually [1].

In the midst of our unprecedented coronavirus pandemic, the morbidity posed by air pollution and its impact on our current situation must not be forgotten. Mortality from air pollution, especially during pandemics, cannot be understated. The devastating 1918 Spanish Influenza Pandemic saw a 10% increase in mortality in large coal-capacity cities.

During the first pandemic of the current century, severe acute respiratory syndrome-associated coronavirus-1 (SARS-CoV-1) in 2003, patients from areas with high air pollution indices (API) displayed a 200% increased relative risk of death compared to people from areas with a low API [2].

Despite this, 91% of the world’s population lives in areas exceeding the recommended World Health Organization (WHO) air quality limits. Thus, a question arises whether there will be any impact of air pollution on the current pandemic coronavirus disease 2019 (COVID-19)?

Effect of air pollutants on host susceptibility to infection

Air pollutants increase host susceptibility to respiratory viral infections by increasing epithelial permeability to viral receptors and reducing surfactant production [3]. They also reduce viral clearance by impairing macrophage-mediated phagocytosis and antigen presentation, expression of both the natural killer and cytotoxic T cells, and allowing viral proliferation, thereby negatively influencing the ability of the host to respond appropriately to infection.

Furthermore, air pollutants increase the virulence of respiratory infections. Nitrogen dioxide (NO2) decreases the minimal infectious dose of murine cytomegalovirus by a factor of 100 and increases rhinovirus infectivity by upregulating its viral receptor. In Italy, a study showed an increase in the environmental concentration of NO2 correlated with an increase in acute respiratory infections by 4% [3].

Exposure to Sulphur dioxide (SO2) has also been associated with an increase in influenza infections [3]. Particulate matter, mainly a diameter of less than 2.5 μm (PM2.5), can reduce phagocytosis of viruses, promote their proliferation, and produce a significant proinflammatory state by inducing the release of cytokines IL-1, IL-6, and TNF-α from alveolar macrophages.

Resultant inflammation can lead to worsening of pre-existing pulmonary morbidities, asthma and chronic obstructive pulmonary disease (COPD) and increase the risk of cardiac disease by altering cardiac autonomic function and accelerating atherosclerosis.

Furthermore, acute and sub-chronic exposure to particulate matter upregulates the angiotensin-converting enzyme 2 (ACE2) receptor, which plays a critical role in the invasion of the SARS-CoV-2 virus into the respiratory epithelium [4].

A statistically significant link has also been demonstrated between acute respiratory distress syndrome (ARDS), and air pollution in the form of PM2.5 and ozone, particularly in elderly adults. This is relevant to COVID-19, given the high rate of death from ARDS [5].

Predisposition due to household air pollution

Often overlooked is the impact of household air pollution (HAP) on susceptibility to respiratory infections. HAP accounts for nearly 16% of the global disease burden from ambient air pollution, accounting for nearly 3.55 million deaths in 2010, and consequently, its impact must not be ignored. A third of the world uses solid fuel for cooking and heating coupled with concomitant cigarette smoking, which can cause epithelial inflammation and predispose acute lower respiratory infections.

HAP can cause dysregulation of the antioxidant: oxidant ratio, reducing antioxidant concentration and promoting oxidative stress. HAP also changes the defense mechanism against infection in the lung, and it is highly plausible that this modification of natural lung flora can result in an increased risk of pulmonary infections.

As an example, cigarette smoke can increase the receptor-dependent adhesion of Streptococcus sp. to the respiratory epithelium. The magnitude of exposure to HAP is also inextricably linked to poor socioeconomic status and noteworthy that the global distribution of poverty and HAP are almost identical. It can be postulated that this exposure, particularly in developing countries or the urban poor in rich countries across the globe, places individuals at high risk of more severe outbreaks of COVID-19 [6].

Early evidence on COVID-19

Thus far, history and science are directing towards an immense potential impact of air pollution on the COVID-19 pandemic. Some of the most devastated countries are those with a poor air quality index, such as China, Northern Italy, and New York City. Considering Northern Italy, in particular, Lombardy and Emilia Romagna are among the most polluted areas in Europe. Mortality here was 12% compared to the rate of 4.5% elsewhere across Italy [7].

In fact, across more than 3000 counties of the United States, an increase of 1 μg/m3 in PM(2.5) has been shown to increase mortality from COVID-19 by 8%, and in New York state alone, by 15% [5]. Like pandemics before, there is likely a positive correlation between air pollutants and the incidence and mortality from COVID-19, but further epidemiological studies are necessary to confirm this hypothesis.

A study recently assessed tropospheric NO2 levels, a marker of atmospheric pollution, in four European countries, Italy, France, Spain and Germany. Chronic NO2 exposure has been linked to background diseases such as hypertension and responsible for the synthesis of proinflammatory cytokines, which are linked to increased COVID-19 mortality.

Of five identified fatality hotspots in Italy and Spain, which accounted for 78% of all deaths, all were shown to have concentrated air pollution [8]. Additionally, in England, both the highest incidence and case-fatality rates occurred around London and the Midlands- regions with the highest concentration of air pollutants. The inverse was seen in regions with less air pollution, giving further support to this notion [9].

In fact, SARS-CoV-2 RNA has been isolated from particulate matter in a study conducted in Bergamo, Northern Italy, suggesting that particulate matter in air pollution may even act as a vector for transmission of COVID-19. This may serve as a possible explanation for a higher COVID-19 burden in areas with high air pollution, and may also be used as an indicator for epidemic recurrence [10].

Imperative interventions

The evidence presented above should serve as a wake-up call for decision-makers keen to advocate planetary health. It is our opinion that there is an unsatisfactory response by many environmental agencies to regulate air pollution, particularly based on the mounting evidence of the influence of air pollution on pandemics of past, present and almost certainly future.

The Paris Agreement, which calls for limiting the influence of climate change, emphasizes the importance of reducing air pollution as a crucial component behind its success. It is crucial that countries globally, now more than ever, appreciate the association between climate change and air pollution, and reduce air pollutants through aggressive policy interventions, not only to potentially reduce the impact of COVID-19 and improve human health, but also to limit climate change.

reference link : https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7458650/


More information: Khomenko S, Cirach M, Pereira-Barboza E, Mueller N, Barrera-Gómez J, Rojas-Rueda D, de Hoogh K, Hoek G, Nieuwenhuijsen M. Premature mortality due to air pollution in European cities; an Urban Burden of Disease Assessment. The Lancet Planetary Health, 2021. https://doi.org/10.1016/S2542-5196(20)30272-2

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