Air pollution may have contributed to 170,000 coronavirus deaths worldwide, a study has claimed.
An international team of researchers estimate 15 per cent of the 1.15million Covid-19 fatalities globally could have been avoided if the air was cleaner.
They said 14 per cent of deaths in the UK could have been prevented, the equivalent of nearly 6,300 lives.
Toxic fumes given off by cars and big industry drive up rates of health conditions which make people more vulnerable to Covid-19.
Previous research has blamed air pollution for about 7million deaths worldwide every year, by aggravating or causing conditions such as high blood pressure, coronary artery disease, diabetes and asthma.
They then used mathematical modelling to calculate how many Covid-19 fatalities could be partly attributed to long-term exposure to toxic air.
The researchers said the figures do not imply that air pollution directly caused deaths from Covid-19 – although they have not ruled it out.
Around 15 per cent of Covid-19 deaths worldwide could have been avoided if the air was cleaner, a study has claimed. The largest proportion of deaths attributed to pollution was in the Czech Republic (29 per cent). Pictured is the percentages for a range of countries
Independent scientists reacting to the findings said it was too early to put a figure on the amount of deaths that may have been as a result of pollution. But they admitted the study's estimates were entirely possible.
The latest study focused on a type of pollution called particulate matter, otherwise known as PM2.5. It is produced mostly by car fumes, construction work and burning fossil fuels.
In the UK, PM2.5 comes from a range of sources including wood burners, road traffic – both from exhaust emissions and brake, tyre and road wear – and industrial, construction and manufacturing processes.
The researchers used satellite data of global exposure to PM2.5 and information on atmospheric conditions to assess how severe pollution was in each country.
WHAT IS PARTICULATE MATTER (PM)?
PM is a mixture of solid particles and liquid droplets found in the air.
They are created from a variety of sources including traffic, construction sites, unpaved roads, fields, smokestacks or fires.
Most particles form in the atmosphere as a result of reactions of chemicals such as sulphur dioxide and nitrogen oxides.
Some PM, such as dust, dirt, soot, or smoke, is large or dark enough to be seen with the naked eye.
Other PM is so small it can only be detected using an electron microscope.
PM2.5 - of diameters that are generally 2.5 micrometers and smaller - differ from PM10 - 10 micrometers and smaller.
Source: US EPA
The degree to which air pollution influences mortality from coronavirus was derived from data a study in the US, and Chinese studies of air pollution and the Sars outbreak in 2003.
A model was created which could calculate how many deaths may have been linked to toxic air as a result of the level of pollution in any given area.
The work suggests 27 per cent of deaths in East Asia could be attributed to air pollution, 17 per cent in North America and around 19 per cent in Europe overall.
The largest proportion of deaths attributed to pollution was in the Czech Republic (29 per cent), followed by Poland (28 per cent), China (27 per cent), North Korea (27 per cent) and Slovakia (27 per cent).
Germany, Hungary, Austria and Belarus were the European countries with more than 25 per cent of deaths attributable to pollution.
The UK was 53rd place in the world, putting it in the top quarter of countries with a higher proportion of deaths linked with toxic air.
In regions with strict air quality standards and relatively low levels of air pollution, such as Australia and New Zealand, pollution was found to be linked to just a few per cent of Covid-19 deaths (three per cent and one per cent, respectively).
One of the authors of the study, Professor Jos Lelieveld, from the Max Planck Institute for Chemistry in Mainz, Germany, and the Cyprus Institute Nicosia, said: 'Since the numbers of deaths from Covid-19 are increasing all the time, it's not possible to give exact or final numbers of Covid-19 deaths per country that can be attributed to air pollution.
'However, as an example, in the UK there have been over 44,000 coronavirus deaths and we estimate that the fraction attributable to air pollution is 14 per cent, meaning that more than 6,100 deaths could be attributed to air pollution.'
The UK's death toll currently stands at 44,896, meaning 6,300 deaths could have been avoided.
Professor Lelieveld added: 'In the USA, more than 220,000 Covid deaths with a fraction of 18 per cent yields about 40,000 deaths attributable to air pollution.'
Pictured: Estimated percentages of Covid-19 mortality attributed to pollution. The darker colours indicate a higher percentage
TOP 20 COUNTRIES WITH THE MOST COVID-19 DEATHS LINKED TO POLLUTION
The 20 countries with the most Covid-19 deaths that may be attributable to high pollution levels (as a percentage) are as follows:
Czech Republic: 29 per cent
Poland: 28 per cent
China: 27 per cent
North Korea: 27 per cent
Slovakia: 27 per cent
Austria: 26 per cent
Belarus: 26 per cent
Germany: 26 per cent
Hungary: 25 per cent
Luxembourg: 25 per cent
Lithuania: 24 per cent
Korea: 23 per cent
Bangladesh: 23 per cent
Republic of Moldova: 22 per cent
Slovenia: 22 per cent
Switzerland: 22 per cent
Belgium: 21 per cent
Latvia: 21 per cent
Romania: 21 per cent
Ukraine: 21 per cent
TOP 20 COUNTRIES WITH THE LEAST COVID-19 DEATHS LINKED TO POLLUTION
The 20 countries with the least Covid-19 deaths that may be attributable to high pollution levels (as a percentage) are as follows:
Maldives: 0 per cent
Grenada: 0 per cent
Vanuatu: 0 per cent
Western Samoa: 0 per cent
Kiribati: 0 per cent
Fiji: 0 per cent
Oman: 1 per cent
Saint Vincent: 1 per cent
Saint Lucia: 1 per cent
Antigua and Barbuda: 1 per cent
Barbados: 1 per cent
Tonga: 1 per cent
New Zealand: 1 per cent
Micronesia: 1 per cent
Niger: 1 per cent
Mauritius: 1 per cent
Mauritania: 1 per cent
Mali: 1 per cent
Cape Verde: 1 per cent
Burkina Faso: 1 per cent
They team said their findings do 'not imply a direct cause-effect relationship between air pollution and Covid-19 mortality (although it is possible)'.
Instead it can only show a relationship between two, and say it is likely Covid-19 aggravates other health conditions 'that could lead to fatal health outcomes of the virus infection'.
Fellow researcher Professor Thomas Münzel, from Johannes Gutenberg University and the German Centre for Cardiovascular Research in Mainz, said inhaled polluting particles cause inflammation and damage to arteries.
It irritates the inner lining of arteries, the endothelium, and leads to the narrowing and stiffening of the arteries.
This pre-existing damage to blood vessels might put a person at heightened risk of severe Covid-19.
Doctors have learnt over the course of the pandemic that Covid-19 is a disease of the vascular system, and not just a respiratory disease.
If a person is infected by the coronavirus, it has the potential to cause abnormal blood clotting, ‘leaky’ vessels and reduced blood flow.
POLLUTION 'CARRIES THE VIRUS'
People are more likely to catch Covid-19 in areas with bad air pollution because particles can 'carry' the virus, scientists claimed in August.
Data shows that London, Birmingham, New York, LA, Mexico city, Delhi all have high levels of pollution and have been battered by Covid-19.
Now, international researchers led by Taipei Medical University in Taiwan have claimed pollution plays a 'direct role' in the spread of the disease.
Viruses may be absorbed by particulate matter - produced mostly by car fumes and construction work - and then travel or linger in the air for hours or even days before being inhaled by someone, they said.
This would suggest the coronavirus is airborne, meaning people can inhale it from tiny particles in the air.
Until now, health officials have said the coronavirus is spread mainly from large respiratory droplets expelled from coughing or sneezing.
But emerging evidence suggests airborne transmission also plays a role.
The scientists said viruses may be absorbed by particulate matter (PM) and remain 'airborne for hours or days'.
The tiny particles can then be inhaled deep into the lungs where the virus begins replicating.
PM may provide 'a good platform to shade and carry the SARS-CoV-2' and be a 'direct transmission model in a highly polluted area', the paper claimed.
There are some studies which support this theory to some extent.
Italian researchers showed how genetic material of SARS-CoV-2 was detectable in 19 of 34 PM samples in Bergamo, Italy.
Various studies in Italy have shown places that have been the hardest hit by Covid-19 also have significant pollution.
Lombardi and Emilia Romagna in northern Italy have a lot of factories, heavy traffic and are surrounded by mountains which prevent air flow.
It's been reported both locations also have a higher Covid-19 mortality rate than other places in Italy. However, there could be many other underlying reasons other than pollution.
In another study spanning 120 cities in China, research showed that every increase of 10 micrograms per cubic meter in concentration of PM2.5 led to more than a two per cent increase in new Covid-19 cases.
But it was later argued that this rise in Covid-19 infection was because of the crowded cities rather than the exposure to air pollution.
The British Heart Foundation says Covid-19 can cause ‘sticky blood’ raising the risk of deep vein thrombosis and blood clots.
Blood clots can lead to strokes or heart attacks, therefore coronavirus patients often die of complications caused by the virus, rather than the virus itself.
Higher levels of D-dimer, a breakdown product of blood clots, have been seen in critically ill patients.
It may explain why people with high blood pressure and diabetes - conditions that both damage blood vessels - are disproportionately dying of Covid-19.
Professor Münzel said: 'If both long-term exposure to air pollution and infection with the Covid-19 virus come together then we have an additive adverse effect on health, particularly with respect to the heart and blood vessels, which leads to greater vulnerability and less resilience to Covid-19.
'If you already have heart disease, then air pollution and coronavirus infection will cause trouble that can lead to heart attacks, heart failure and stroke.'
The gateway for viral entry in the lung, the ACE2 receptor, is also found on the endothelial cells lining blood vessels.
The coronavirus latches onto the ACE2 receptor by binding to it and then it replicates inside the cell.
Professor Münzel and colleagues believe PM may make the lungs more susceptible to the coronavirus by increasing the expression of ACE-2 receptors that coat cells.
He said: 'So we have a "double hit": air pollution damages the lungs and increases the activity of ACE-2, which in turn leads to enhanced uptake of the virus by the lungs and probably by the blood vessels and the heart.'
The study also said 'it seems likely' that the fine polluting particles prolong the time infectious viruses survive in the air.
Viruses may be absorbed by particulate matter and then travel or linger in the air for hours or even days before being inhaled by someone.
The tiny particles can then be inhaled deep into the lungs where the virus begins replicating.
This would suggest the coronavirus is airborne, meaning people can inhale it from tiny particles in the air. But this is not considered the main route of transmission - droplets from coughs and sneezes is.
Professor Lelieveld said: 'It's likely that particulate matter plays a role in "super-spreading events" by favouring transmission.'
Commenting on the study, Professor Anna Hansell, from the University of Leicester, said: 'While it is extremely likely that there is a link between air pollution and Covid-19 mortality, it is premature to attempt to precisely quantify it, as here, given the current state of the evidence.
'However, there are plenty of other good reasons to act now to reduce air pollution, which the WHO (World Health Organisation) already links to seven million deaths worldwide per year.'
Professor Hansell noted the study was limited by the fact it only used two studies to come to its conclusions.
The US study has not yet completed the full peer review process, and so the associations reported may change afterwards.
The second study relates to SARS in China in 2003 and not to Covid-19.
SARS appeared in China in the early 2000s and led to more than 8,000 cases in 26 countrie, but was contaned by 2003.
The virus has many similarities to SARS-CoV-2, the virus which causes Covid-19. Both are zoonotic diseases, thought to have jumped from animals to humans, and bind to the same receptor to enter cells (ACE-2).
But the study's findings, although valid, would have been more accurate had it used data from SARS-CoV-2.
The research team was led by Andrea Pozzer of the International Center for Theoretical Physics, Trieste, Italy. But it involved researchers from Germany, the US, Britain and Cyprus.
The researchers said the majority of the particulate matter came from fossil fuels and called for efforts to cut emissions.
Writing in the medical journal, they said: 'A lesson from our environmental perspective of the Covid-19 pandemic is that the quest for effective policies to reduce anthropogenic emissions, which cause both air pollution and climate change, needs to be accelerated.
'The pandemic ends with the vaccination of the population or with herd immunity through extensive infection of the population.
'However, there are no vaccines against poor air quality and climate change. The remedy is to mitigate emissions.'
Poor air quality, especially from PM2.5 is responsible for many excess death globally. exceeding those caused by infectious diseases, the team said.
Air pollution affects all regions of the world, but more so in low-income cities, 97 per cent of which do not meet air quality guidelines set out by the World Health Organization (WHO).
Even in high-income countries, 49 per cent are breaching pollution limits.
There are particularly high exposures in the Eastern Mediterranean, South‐East Asian and Western Pacific regions.
However, it is the US, Europe and Latin America which has been significantly impacted by Covid-19, if looking at government reported data on cases and deaths.