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How Does Air Pollution Compromise the Human Immune System?

According to recent research published in the European Respiratory Journal, exposure to air pollution resulted in an extra four days in hospital for COVID-19 patients, expanding the burden on healthcare systems.

How Does Air Pollution Compromise the Human Immune System?

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According to the investigators, the impact of pollution on patients’ hospital stay was similar to being a decade older. Reducing pollution exposure, on the other hand, was 40 to 80% effective in minimizing hospitalization duration as some of the best available treatments.

The study analyzed data on all 3.7 million Danish individuals aged 30 or older in a second study, also published in the European Respiratory Journal, to determine the influence of air pollution on COVID-19.

Long-term exposure to pollution at levels much below current EU limits increased the likelihood of getting COVID-19, being hospitalized, and dying from the disease, according to the researchers.

Professor Tim S. Nawrot of Hasselt University in Belgium directed the first study. It includes 328 COVID-19 patients who were hospitalized between May 2020 and March 2021.

The researchers used data from three pollutants—nitrogen dioxide, soot, and fine particles (PM2.5)—at the patients’ residence address before they were admitted to the hospital with COVID-19. They also measured how much soot was in the patients’ blood.

The investigators contrasted this information to clinical outcomes, like how long patients stayed in the hospital before being able to go home and if they were treated in intensive care. They considered other characteristics known to influence COVID-19 infection, including age, gender, and body mass index.

This indicated that those who were exposed to greater levels of fine particles and nitrogen dioxide in the week preceding their hospitalization had to stay in the hospital for more than four days on average.

However, all levels of exposure were lower than the EU limit. The magnitude of the impact of air pollution on hospitalization time was similar to a 10-year age rise. The findings also revealed that COVID-19 patients who had been exposed to higher levels of nitrogen dioxide and soot during the previous four years stayed in the hospital for longer on average.

Scientists discovered that higher amounts of soot in patients’ blood raised the risk of them requiring intensive care treatment by 36%.

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.

Tim S. Nawrot, Professor, Hasselt University

The second study integrated data from the Danish National COVID-19 Surveillance System from the first 14 months of the pandemic with accurate data on air pollution levels at people’s home addresses over the past 20 years.

They discovered that even at levels much below current EU limits, elevations in long-term exposure to nitrogen dioxide and fine particles increased the probability of getting COVID-19, being hospitalized, and dying from the disease.

Individuals with certain medical conditions, like asthma, heart disease, diabetes, and dementia, as well as those from lower-income families, were more vulnerable to the combined effects of air pollution and COVID-19.

These results show how air pollution can compromise our immune system and leave us vulnerable to Covid-19 and other respiratory infections. Reduction of air pollution should be in the heart of preventive measures for current and future pandemics, as well as a strategy for dealing with seasonal influenza pandemics. Cleaner air would make populations more resilient to respiratory infections, seasonal epidemics, and major pandemics in future.

Dr. Zorana Jovanovic Andersen, Study Author, University of Copenhagen

Professor Charlotte Suppli Ulrik from the University of Copenhagen, Denmark says, “We are finding more and more evidence that breathing polluted air is contributing to lung diseases, including infections. These studies show how exposure to air pollution at levels that are common in cities around Europe increased people’s risk of contracting Covid-19, becoming seriously ill and dying.”

Professor Ulrik is the Head of the European Respiratory Society Assembly on the Environment and Epidemiology and was not involved in the research.

She concludes, “The research also indicates how pollution exacerbated the strain on our hospitals and health services. Although the Covid-19 global health emergency is over, the impact of pollution on our health is continuing and we need governments to take action for the sake of our health and our health services.”


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