Growing evidence links air pollution exposure to covid-19 risks

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Research has shown that not being vaccinated increases the risk of being infected with the coronavirus, while being older, overweight or immunocompromised can increase the severity of the disease. Now scientists believe there is another risk factor that can increase the likelihood of contracting the coronavirus and the possibility of it leading to a poor outcome: exposure to air pollution.

A growing body of evidence suggests links between breathing polluted air and the risks of becoming infected with the coronavirus, developing serious illness or dying from covid-19. While many of these studies have focused on long-term exposure to air pollution, experts say there is also evidence that even short-term exposures can have negative effects.

A recent study of 425 young adults in Sweden found that brief exposures were “associated with an increased risk of SARS-CoV-2 infection despite relatively low levels of air pollution exposure”, according to the article published in April. Unlike many other studies that analyzed vulnerable populations, such as the elderly or young children, and tracked the effects of long-term exposures on hospitalizations and deaths, the median age of participants, who largely reported mild to moderate symptoms, was about 25 years old. .

The results will hopefully raise awareness “that this type of exposure can be harmful to everyone,” said Erik Melén, the study’s lead researcher and professor in the Department of Clinical and Health Sciences. education from the Karolinska Institutet in Sweden.

Zhebin Yu, lead author of the study and a researcher at Karolinska Institutet, noted that the research was based on people who were not vaccinated during an earlier phase of the pandemic. So the results, he said, might not be applicable to newer coronavirus variants, such as omicron, and to vaccinated people.

The findings, however, add to the understanding that when it comes to health effects, including the risk of covid, “there is no safe limit or safety threshold of air pollution. air,” said Olena Gruzieva, an associate professor at the Karolinska Institutet who worked on the study.

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Scientists are still trying to determine how exposure to air pollution might increase covid risks. But there are a few theories.

Exposure to pollutants, for example, is linked to inflammation and an imbalance in the body known as oxidative stress – both of which could exaggerate a person’s response to any virus, including coronavirus, said Meredith McCormack, volunteer medical spokesperson for the American Lung Association.

Another theory suggests that breathing polluted air could help the virus penetrate deeper into the body or cells, added McCormack, who is an associate professor of medicine at Johns Hopkins. Pollution can also alter the immune response.

Pollution exposures documented in many studies that have shown an impact on covid are generally lower than current regulatory standards set by the Environmental Protection Agency, Alison Lee said. Lee is a lung specialist at Mount Sinai in New York who has published research on air pollution and covid.

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It’s critical, McCormack and other experts said, that people protect themselves on poor air quality days and that individuals and governments work to reduce air pollution.

“The transition to a green economy with green renewable energy resources will really further protect both the environment and public health, and it is also very closely related to the climate change crisis,” said Donghai Liang, professor environmental health and epidemiology assistant at Emory. University.

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Concerns about exposure to air pollution and covid have existed since the early months of the pandemic. A Harvard University study that analyzed coronavirus data from US counties through June 2020 found that “a slight increase in long-term exposure” to fine particulate matter – one of the most insidious types of air pollution – “leads to a sharp increase in the death rate from covid-19.

Another study of US county-level data from the early months of the pandemic reported that chronic exposure to nitrogen dioxide (NO2), an air pollutant from traffic and power plants, was associated with a significant increase in covid death and death rate.

“If we had done a better job earlier, if we could have reduced long-term exposure to NO2 by 10%, it would have prevented more than 14,000 deaths among people who tested positive for the virus in July 2020,” said said Liang, the study’s lead author.

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Researchers and outside experts have noted that such population-based observational studies cannot account for individual risk factors that can affect a person’s chances of becoming seriously ill or dying after contracting the coronavirus.

A “more rigorous approach” is to follow individuals over a period of time and track who is infected with the virus and then develops severe covid symptoms, requires hospitalization or dies, said Kai Chen, assistant professor at the Yale School of Public Health and Research Director at the Yale Center on Climate Change and Health.

He and other experts have called for additional research to clarify some key questions.

“There is still some uncertainty about the magnitude of the risk,” McCormack said. “For a given increase in air pollution on a given day, does that increase your risk of contracting covid by 1% or 5%, more than 5%? These estimates are still being refined.

Researchers also need to determine exactly what can influence a person’s risk of contracting the coronavirus and the severity of infection, said Chen, who published a study showing that certain weather factors, such as humidity, could affect the ability of the virus to spread. If a major confounding variable is not controlled for in the statistical analysis of a study, it could lead to overestimating the effect of air pollution, he said.

Additionally, research should continue into the potential harms of short-term exposure, Lee said. “It is important to see the data in the short term because this data fills a critical gap and therefore has policy implications.”

Because long-term data averages exposures over longer time periods, it “can mask peaks in exposure,” Lee said. Low-income communities and people of color, many of whom tend to live closer to sources of air pollution, are often disproportionately affected by these spikes. “By strengthening long- and short-term air quality standards and placing more regulatory monitors near these exposure hotspots, we can better improve health in environmental justice communities,” a- she declared.

It’s unclear whether increased exposure to pollutants is responsible for pandemic-related health disparities in those communities, which have been hit hardest by the coronavirus, McCormack said. “We haven’t had a study yet that disentangles all the factors,” she said, “but we certainly know that by quantifying the effect of air pollution on infection with covid, we have evidence that this is one of the driving forces likely contributing to the differences we’ve seen – but it’s one of many.

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Experts said they hope findings linking air quality and covid will help bring the issue of how air pollution affects our health to the forefront of public consciousness.

“Air pollution is like a silent pandemic,” Chen said. Although the impact of pollution on the environment is well known, fewer people might be aware that exposure to outdoor and indoor air pollution causes an estimated 7 million premature deaths worldwide each year and is associated with lung and heart disease, among other serious health problems.

The coronavirus pandemic, however, “has really raised awareness of the importance of clean air,” McCormack said.

Lee agreed. “The overall conclusion from all these studies is that air pollution is bad and we really need to fight for more protective air quality standards,” she said.

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