Higher levels of air pollution 'linked to deadlier cases of Covid-19'

23 April 2020, 21:19

A man walks down empty Oxford Street in central London during the coronavirus lockdown
A man walks down empty Oxford Street in central London during the coronavirus lockdown. Picture: PA

By Amelia Harper

Scientists say they have found a link between high pollution levels and the most serious cases of coronavirus.

Preliminary findings by scientists at the University of Cambridge indicate that worst cases of coronavirus tend to occur in parts of England with higher levels of air pollution.

Researchers found that there was a positive correlation between places with higher pollution levels, and the number of Covid-19 cases and deaths.

The study found that London and the Midlands, which both recorded high nitrogen dioxide concentrations in the air in recent tests, were associated with deadlier cases of Covid-19.

The study’s senior author, Dr Miguel Martins, said: “pollutants can cause an inflammatory response which increases the risk of respiratory infections – such as Covid-19".

The new published study is not yet peer reviewed but researchers say there is an urgent need to share information relating to the pandemic.

Dr Martins added that “air pollution is formed by particles that are very small. These can reach the lungs and the exposure to these particles increases the risk of dying from cardiovascular or respiratory diseases”.

“So patients with Covid-19, who have these diseases are more likely to die than those who don’t”.

The team analysed data on total Covid-19 cases and deaths and compared it against levels of three major air pollutants, collected between the years 2018 and 2019, prior to the outbreak.

Marco Travaglio, a PhD student at the MRC Toxicology Unit said “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.”

Researchers accounted for population density in their data analysis and found that the association was independent of the population density.

Dr Miguel Martins 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”.

He added that these preliminary findings “suggest that we need to explore further, for example in big cities like London, pollution is causing more severe cases of COVID-19."

In London, lockdown has led to a decrease in traffic and pollution levels.

“It will be interesting to study if this decrease in pollution also decreases the severity of COVID-19 cases," said Dr Martins.

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London’s Mayor Sadiq Khan today said the capital’s air quality has "dramatically improved" due to a cut in traffic caused by the coronavirus lockdown.

Figures published by the mayor show that average levels of key pollutant nitrogen dioxide (NO2) at some of the capital's busiest roads are around half what they were before the pandemic.

Separate data published by the University of York shows that Nitrous Oxide levels in Birmingham dropped by around 42%, Manchester 39%, Bristol 31% and Belfast 30%, while York has seen a fall of 11%.

The researchers say that their findings only show a correlation and that further research is needed to confirm that air pollution makes COVID-19 worse.

The research was supported by the Medical Research Council.