Air pollution may be 'major contributor' to COVID-19 deaths

High levels of air pollution may be ‘one of the most important contributors’ to deaths from coronavirus with 78 per cent of COVID-19 fatalities in Europe occurring in areas with high levels of nitrogen dioxide

  • In Europe 78 per cent of coronavirus deaths occurred in the most polluted areas
  • Two studies examined the link between high levels of air pollution and COVID-19
  • They found a link between nitrogen dioxide in the atmosphere and death rates 
  • Learn more about how to help people impacted by COVID

More people are dying from coronavirus in areas of the world with higher pollution levels, studies looking at death rates in Europe and the USA have found.

In a European study, researchers from Martin Luther University in Germany looked at death rates across 66 administrative regions in Italy, Spain, France and Germany.

They found that 78 per cent of deaths occurred in the five most polluted regions of the four countries they studied.

A similar study into COVID-19 death rates in different parts of England by the University of Cambridge also shows the death rate is higher in areas with increased levels of pollution.

An earlier study looking at US pollution and death rates from COVID-19 found even small increases in nitrogen dioxide levels saw a rise in death rates from coronavirus. 

Milan (pictured) has high levels of air pollution and was also hit hard by the coronavirus outbreak.  In the European study researchers from Martin Luther University, Germany, looked at death rates across 66 administrative regions in Italy, Spain, France and Germany

Levels of nitrogen dioxide (NO2), which is produced by diesel vehicles and industrial activity, were measured as part of all three studies, as well as particle matter.

‘The results indicate that long-term exposure to this pollutant may be one of the most important contributors to fatality caused by the Covid-19 virus in these regions and maybe across the whole world,’ said Yaron Ogen of the German team. 

‘Poisoning our environment means poisoning our body, and when it experiences chronic respiratory stress its ability to defend itself from infections is limited.’

Cambridge researchers looked at COVID-19 death rates in England from areas with at least 2,000 cases – then compared them to data on major air pollutants.

The largest number of deaths in England occurred across London and the Midlands – also the two areas with the highest concentration of nitrogen dioxide.

NO2 has been shown to be linked to a number of human health problems, including lung disease – which studies show could increase the risk of death from COVID-19.  

ESA says nitrogen dioxide levels in Madrid dropped by 48 per cent, in Milan they were down by 47 per cent and in Rome they were 49 per cent lower than the year before

The European Space Agency revealed a dramatic drop of NO2 levels across Europe since the start of lockdown measures to slow the spread of COVID-19.

In some areas the amount of NO2 in the atmosphere over cities like Milan, Paris and Madrid were down by as much as 50 per cent compared to the year before. 

Air pollution weakens the body’s respiratory tract and inhibits its ability to prevent infection, which is known to lead to higher death rates from all causes. 

However, this association was 20 times stronger for the COVID-19 disease, caused by the SARS-CoV-2 virus, according to the Harvard team. 

The German team used data from the European Space Agency Sentinel 5P satellite to map the distribution of NO2 across the continent in the months leading to the pandemic outbreak.

They looked at COVID-19 deaths from 66 regions of Italy, Spain, France and Germany up to March 19 and compared their locations to areas of pollution.

They found that of the 4,443 deaths during that time 78 per cent were in five regions in north Italy and central Spain – the five regions that had the highest nitrogen dioxide concentrations.


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 

This was combined with a downwards airflow which prevented air pollution being dispersed away from those areas, said Ogen. 

Researchers from Harvard University examined the impact of NO2 and particle matter on the death rates from coronavirus across the US. 

They found that higher levels of PM2.5 – the tiny pollutant particles created by industry – lead to a severe spike in death rates from COVID-19.

‘We found that an increase of only 1μg/m3 in PM2.5 [particles] is associated with a 15 per cent increase in the Covid-19 death rate,’ the team write in their shocking study. 

Air pollution data from around 3,000 US counties, which accounts for 98 per cent of the country’s population, was pooled and compared to coronavirus statistics.   

They adjusted the figures for factors which can skew the findings, such as poverty levels, smoking, obesity, and the number of tests and hospital beds available.

British researchers looking at data on COVID-19 deaths and air pollution in England  found that the  higher the pollutant levels, the greater the number of COVID-19 cases and deaths.  

Marco Travaglio, a PhD student at the MRC Toxicology Unit, said: ‘Our results provide the first evidence that SARS-CoV-2 case fatality is associated with increased nitrogen oxide and nitrogen dioxide levels in England. 

‘London, the Midlands and the North West show the largest concentration of these air pollutants, with Southern regions displaying the lowest levels in the country, and the number of COVID-19 deaths follows a similar trend.’ 

There were limitations to the studies – they didn’t account for differences in availability of medical resources due to lack of data.

Pictured, county level data from 17 years of historical records revealing average PM2.5 concentrations in the US in g/m3. Researchers found that even a small increase in PM2.5 concentration is linked to a significantly higher chance of death after contracting the coronavirus

Pictured, county level number of COVID-19 deaths per one million population in the US up to and including April 4, 2020. Coronavirus deaths was compared to air pollution data and a significant correlation was found 

The European study also didn’t consider age distribution or pre-existing conditions. 

The teams say more work is needed to examine nitrogen dioxide and PM2.5 and the relationship exposure to the pollutants has on on COVID-19 death rates.

They say the preliminary results give an insight into how small air quality changes lead to a difference in the number of lives lost to viruses.  

‘The study results underscore the importance of continuing to enforce existing air pollution regulations to protect human health both during and after the COVID-19 crisis,’ write the Harvard researchers. 

Dr Miguel Martins, senior author on the English study, said: ‘Our study adds to growing evidence from Northern Italy and the USA that high levels of air pollution are linked to deadlier cases of COVID-19.

‘This is something we saw during the previous SARS outbreak back in 2003, where long-term exposure to air pollutants had a detrimental effect on the prognosis of SARS patients in China. 

‘This highlights the importance of reducing air pollution for the protection of human health, both in relation to the COVID-19 pandemic and beyond.’

The European paper has been published in the journal Science of The Total Environment and the US paper has been submitted for inclusion in the New England Journal of Medicine but is available now on the pre-print server medRxiv. 

The English study is also available on medRxiv prior to submission for peer-review.



Carbon dioxide

Carbon dioxide (CO2) is one of the biggest contributors to global warming. After the gas is released into the atmosphere it stays there, making it difficult for heat to escape – and warming up the planet in the process. 

It is primarily released from burning fossil fuels such as coal, oil and gas, as well as cement production. 

The average monthly concentration of CO2 in the Earth’s atmosphere, as of April 2019, is 413 parts per million (ppm). Before the Industrial Revolution, the concentration was just 280 ppm. 

CO2 concentration has fluctuated over the last 800,000 years between 180 to 280ppm, but has been vastly accelerated by pollution caused by humans. 

Nitrogen dioxide 

The gas nitrogen dioxide (NO2) comes from burning fossil fuels, car exhaust emissions and the use of nitrogen-based fertilisers used in agriculture.

Although there is far less NO2 in the atmosphere than CO2, it is between 200 and 300 times more effective at trapping heat.

Sulfur dioxide 

Sulfur dioxide (SO2) also primarily comes from fossil fuel burning, but can also be released from car exhausts.

SO2 can react with water, oxygen and other chemicals in the atmosphere to cause acid rain. 

Carbon monoxide 

Carbon monoxide (CO) is an indirect greenhouse gas as it reacts with hydroxyl radicals, removing them. Hydroxyl radicals reduce the lifetime of carbon dioxide and other greenhouse gases. 


What is particulate matter?

Particulate matter refers to tiny parts of solids or liquid materials in the air. 

Some are visible, such as dust, whereas others cannot be seen by the naked eye. 

Materials such as metals, microplastics, soil and chemicals can be in particulate matter.

Particulate matter (or PM) is described in micrometres. The two main ones mentioned in reports and studies are PM10 (less than 10 micrometres) and PM2.5 (less than 2.5 micrometres).

Air pollution comes from burning fossil fuels, cars, cement making and agriculture 

Scientists measure the rate of particulates in the air by cubic metre.

Particulate matter is sent into the air by a number of processes including burning fossil fuels, driving cars and steel making.

Why are particulates dangerous?

Particulates are dangerous because those less than 10 micrometres in diameter can get deep into your lungs, or even pass into your bloodstream. Particulates are found in higher concentrations in urban areas, particularly along main roads. 

Health impact

What sort of health problems can pollution cause?

According to the World Health Organization, a third of deaths from stroke, lung cancer and heart disease can be linked to air pollution. 

Some of the effects of air pollution on the body are not understood, but pollution may increase inflammation which narrows the arteries leading to heart attacks or strokes. 

As well as this, almost one in 10 lung cancer cases in the UK are caused by air pollution. 

Particulates find their way into the lungs and get lodged there, causing inflammation and damage. As well as this, some chemicals in particulates that make their way into the body can cause cancer. 

Deaths from pollution 

Around seven million people die prematurely because of air pollution every year. Pollution can cause a number of issues including asthma attacks, strokes, various cancers and cardiovascular problems. 


Asthma triggers

Air pollution can cause problems for asthma sufferers for a number of reasons. Pollutants in traffic fumes can irritate the airways, and particulates can get into your lungs and throat and make these areas inflamed. 

Problems in pregnancy 

Women exposed to air pollution before getting pregnant are nearly 20 per cent more likely to have babies with birth defects, research suggested in January 2018.

Living within 3.1 miles (5km) of a highly-polluted area one month before conceiving makes women more likely to give birth to babies with defects such as cleft palates or lips, a study by University of Cincinnati found.

For every 0.01mg/m3 increase in fine air particles, birth defects rise by 19 per cent, the research adds. 

Previous research suggests this causes birth defects as a result of women suffering inflammation and ‘internal stress’. 

What is being done to tackle air pollution? 

Paris agreement on climate change

The Paris Agreement, which was first signed in 2015, is an international agreement to control and limit climate change. 

It hopes to hold the increase in the global average temperature to below 2°C (3.6ºF) ‘and to pursue efforts to limit the temperature increase to 1.5°C (2.7°F)’.

Carbon neutral by 2050 

The UK government has announced plans to make the country carbon neutral by 2050. 

They plan to do this by planting more trees and by installing ‘carbon capture’ technology at the source of the pollution.

Some critics are worried that this first option will be used by the government to export its carbon offsetting to other countries.

International carbon credits let nations continue emitting carbon while paying for trees to be planted elsewhere, balancing out their emissions.

No new petrol or diesel vehicles by 2040

In 2017, the UK government announced the sale of new petrol and diesel cars would be banned by 2040. 

From around 2020, town halls will be allowed to levy extra charges on diesel drivers using the UK’s 81 most polluted routes if air quality fails to improve.

However,  MPs on the climate change committee have urged the government to bring the ban forward to 2030, as by then they will have an equivalent range and price.

The Paris Agreement, which was first signed in 2015, is an international agreement to control and limit climate change. Pictured: air pollution over Paris in 2019.

Norway’s electric car subsidies

The speedy electrification of Norway’s automotive fleet is attributed mainly to generous state subsidies. Electric cars are almost entirely exempt from the heavy taxes imposed on petrol and diesel cars, which makes them competitively priced.

A VW Golf with a standard combustion engine costs nearly 334,000 kroner (34,500 euros, $38,600), while its electric cousin the e-Golf costs 326,000 kroner thanks to a lower tax quotient. 

Criticisms of inaction on climate change

The Committee on Climate Change (CCC) has said there is a ‘shocking’ lack of Government preparation for the risks to the country from climate change. 

The committee assessed 33 areas where the risks of climate change had to be addressed – from flood resilience of properties to impacts on farmland and supply chains – and found no real progress in any of them.

The UK is not prepared for 2°C of warming, the level at which countries have pledged to curb temperature rises, let alone a 4°C rise, which is possible if greenhouse gases are not cut globally, the committee said.

It added that cities need more green spaces to stop the urban ‘heat island’ effect, and to prevent floods by soaking up heavy rainfall. 

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