Exposure to air pollution could reduce levels of key gut bacteria, which plays a role in reducing the risk of complications post-COVID and may reduce severity of infection
One in 25 adults report suffering from long-term COVID-19 after their first infection, and location could heighten risk, according to the first study to link air pollution with long COVID in young people.
Adults aged 26-28 living in highly populated areas and exposed to relatively high levels of air pollution pre-pandemic, especially fine particles from traffic, were 28% more likely to suffer symptoms of long COVID.
The association persisted after factoring in socioeconomic status, smoker status and other health conditions like asthma, and was stronger for specific long COVID symptoms, especially those related to respiratory health.
“Air pollution has been linked to multiple adverse health outcomes in previous studies, including COVID-19 related death and disease severity,” said Zhebin Yu, lead author from the Karolinska Intitutet.
The data, collected as part of Sweden’s ongoing BAMSE birth cohort study, revealed one in six respondents who’d had a mild/moderate COVID infection had lingering symptoms and corroborates a 2021 Imperial College London (ICL) study linking long-term exposure to air pollution pre-pandemic and susceptibility to hospital admissions from COVID-19.
The study “focused on analysing the available epidemiological and toxicological evidence on air pollution and COVID-19, and evidence on air pollution and hospital admissions for lower respiratory infections,” said Shawn Lee, PhD student in the Air Pollution Epidemiology Team at ICL.
Its currently unknown why air pollution may be linked to long COVID, but there’s a well-established link between air pollution and lung and heart disease which could make people more vulnerable to adverse outcomes from COVID-19, suggested ICL’s study.
Air pollution triggers inflammation in the body’s tissues and organs, which usually protects against damaging pathogens. However, inflammation can also be harmful with long-term inflammation linked to air pollution potentially triggering symptoms reported by those experiencing long COVID.
“Recent research shows gut bacteria, bifidobacteria reduce risk of complications post-COVID and may reduce severity of infection.”
Another possible explanation is that exposure to air pollution could reduce levels of key gut bacteria, such as bifidobacterial, in city dwellers said Dr Ben Sinclair, founder of Dr Finlay’s Private Practice, and who has recovered from long COVID.
“Research evidence indicates that viral infections in the respiratory tract initiate a disturbance in the gut microbiome and low levels of bifidobacteria are more common in those with long COVID. Recent research shows bifidobacteria reduce risk of complications post-COVID and may reduce severity of infection.”
Further research will clarify why air pollution increases the risk of severe outcomes, determine possible mechanisms for why those in highly polluted areas are more likely to develop long COVID and explore whether there’s a similar link in different age groups. It will also evaluate whether vaccination alters this link, as the research was conducted before most participants received the COVID-19 vaccine.
The work illustrates just how harmful air pollution is to human health and what needs to be done to reduce air pollution levels worldwide to improve all aspects of health.
A 2021 report from ICL also found a link between long-term exposure to air pollution and the severity with which a person experiences the effects of COVID-19.
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