How air pollution can affect covid-19 risks

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Research has shown that being unvaccinated increases the risk of becoming 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 could increase the chances of contracting the coronavirus and the possibility of it leading to a bad outcome: exposure to air pollution.

A growing body of evidence suggests links between breathing polluted air and the chance of becoming infected with the coronavirus, developing a 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 mounting evidence that even short-term exposure can have negative effects.

A recent study of 425 younger adults in Sweden found that short-term exposure was “associated with an increased risk of SARS-CoV-2 infection despite relatively low levels of exposure to air pollution,” 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 exposure on hospitalizations and death, the median age of participants, who reported largely mild to moderate symptoms, was approximately 25 years. old. †

The findings will hopefully raise awareness “that these types of exposures can be harmful to anyone,” said Erik Melén, the study’s lead researcher and a professor in the department of clinical science and education at the Karolinska Institutet in Sweden.

Zhebin Yu, the lead author of the study and a researcher at the Karolinska Institutet, noted that the study was based on unvaccinated people during an earlier phase of the pandemic. So the results, he said, may not apply to more recent variants of the coronavirus, such as omicron, and vaccinated individuals.

However, the findings add to the understanding that when it comes to health effects, including the risk of covid, “there is no safe limit or safe threshold for air pollution,” 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 could increase covid risks. But there are some theories.

For example, exposure to pollutants has been linked to inflammation and an imbalance in the body known as oxidative stress — both of which can exaggerate a person’s response to a virus, including the coronavirus, said Meredith McCormack, a volunteer medical spokesperson for the United Nations. American Lung Association.

Another theory suggests that breathing polluted air can 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 impair the immune response.

The pollution exposure documented in many of the studies that have shown an impact on Covid is generally below 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 poorer air quality days and that individuals and governments work to reduce air pollution.

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

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Since the early months of the pandemic, there have been concerns about exposure to air pollution and Covid. A Harvard University study that analyzed coronavirus data from counties across the United States through June 2020 found that “a small increase in long-term exposure” to particulate matter — one of the most insidious forms of air pollution — “leads to a large increase in the death rate.” by covid-19.”

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

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

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

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

He and other experts called for further 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 any given day, does that increase your risk of getting Covid by 1 percent or 5 percent, more than 5 percent? Those estimates are still being refined.”

Researchers also need to determine exactly what might affect a person’s risk of contracting the coronavirus and the severity of the infection, said Chen, who published a study that found that certain meteorological factors, such as humidity, affect the virus’ ability to spread. can affect their distribution. Failure to control a key confounding variable in the statistical analysis of a study could lead to an overestimation of the effect of air pollution, he said.

In addition, research should continue into the potential harms of short-term exposure, Lee said. “It’s important to see the short-term data because this data fills a critical data gap and thus has policy implications.”

Because long-term data averages exposures over longer periods, “peaks in exposure can be hidden,” Lee said. Lower-income communities of people of color, many of whom tend to live closer to sources of air pollution, are often disproportionately affected by such spikes. “By strengthening both 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,” she said.

Whether increased exposure to pollutants is responsible for pandemic health disparities in these communities, which have been hit harder by the coronavirus, is unclear, McCormack said. “We haven’t had a study that unravels all the factors,” she said, “but we know for sure that by quantifying the effect of air pollution on covid infection, we have evidence that that’s one of the drivers likely contributing to the differences we’ve seen – but it’s one of many.”

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Experts said they hope the findings linking air quality and Covid will bring the issue of air pollution’s toll on our health to the forefront of public awareness.

“Air pollution is like a silent pandemic,” Chen said. Although the impact of pollution on the environment is well known, fewer people are aware that exposure to indoor and outdoor 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.

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

Lee agreed. “The overarching conclusion of 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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