Exposure to air pollution increased length of hospital stays for Covid-19 patients

Two different pieces of research, one in Belgium and one in Denmark have found that air pollution, even in low quantities, increases the risk of contracting Covid-19, increases the risk of being hospitalised by it and leads to an average of four extra days in hospital.

The Belgian study, led by Professor Tim S. Nawrot from Hasselt University included 328 patients who were hospitalised for Covid-19 between May 2020 and March 2021.

Visualization of the coronavirus causing COVID-19

The team took data on levels of  NO2, soot and PM2.5  at the patients’ home addresses before they were hospitalised with Covid-19. They also measured the amount of soot in the patients’ blood.

They compared this data with clinical outcomes, such as how long patients had to remain in hospital before they were well enough to go home and whether they were treated in intensive care. They took account of other factors that are known to affect Covid-19 infection, such as age, sex and body-mass index.

They found that exposure to higher levels of air pollution meant an average of around four extra days in hospital for Covid-19 patients, pointing out that the effect of pollution on the patients’ time in hospital was equivalent to being a decade older. 

The results also suggested that average exposure to higher levels of nitrogen dioxide and soot over the previous four years meant Covid-19 patients stayed longer in hospital on average and it was found that higher levels of soot in the patients’ blood increased the likelihood of needing intensive care treatment by 36%.

Professor Nawrot said: ‘Our findings indicate that people who were exposed to air pollution, even at relatively low levels, were sicker and needed more time in hospital to recover. The pandemic placed an enormous strain on doctors, nurses and other healthcare workers. Our research suggests that air pollution made that burden even greater.’

Researchers in the Danish study used data from the Danish National Covid-19 Surveillance System from the first 14 months of the pandemic combined with detailed information on the levels of air pollution at people’s home addresses over the previous 20 years.

They found that long-term exposure to pollution at levels well below current EU limits increased the risk of contracting Covid-19, being hospitalised and dying of the disease.

People living with certain medical conditions, such as heart disease, asthma, diabetes and dementia, and those from more deprived backgrounds were even more susceptible the combined effects of air pollution and Covid-19.

Study author Dr Zorana Jovanovic Andersen from the University of Copenhagen, Denmark said: ‘These results show how air pollution can compromise our immune system and leave us vulnerable to Covid-19 and other respiratory infections.’

Photo: Fusion Medical Animation


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