Long-term exposure to air pollution appears to have a significant influence on outcomes for people hospitalised with Covid-19, according to a large observational study conducted by the European Society of Clinical Microbiology and Infectious Diseases.
To examine the association between air pollution and Covid-19, the researchers analysed data from 2,038 adults with Covid-19 admitted to four large hospitals in the US.
The researchers collected data on where the participants lived as well as data from the US Environmental Protection Agency on local air pollution levels.
They found that each small (ug/m³) increase in long-term exposure to particulate matter (PM2.5) was associated with more than three times the odds of being mechanically ventilated and twice the likelihood of a stay in ICU.
They also found that patients who were black, male, obese or had more severe long-term health conditions were much more likely to be mechanically ventilated and admitted to the ICU.
Even after accounting for potentially influential factors, including age and underlying health conditions, the researchers found that higher PM2.5 exposure was an independent predictor for mechanical ventilation and ICU stay.
Dr Shallal, lead author of the study said: ‘The key takeaway is that living in a more polluted neighbourhood is an independent risk factor for severity of Covid-19 disease.
‘Although it is not clear how air pollutants contribute to more severe disease, it’s possible that long-term exposure to air pollution may impair the immune system, leading both to increased susceptibility to viruses and to more severe viral infections. In a double hit, fine particles in air pollution may also act as a carrier for the virus, increasing its spread.
‘Urgent further research is needed to guide policy and environmental protection, to minimise the impact of Covid-19 in highly industrialised communities that are home to our most vulnerable residents.’
The authors point out that their study was observational, so can’t establish a cause. They also add that while they adjusted for several influential factors, it is still possible that other factors which could not be fully controlled for, including the severity of disease at the time of presentation, may contribute to the outcomes observed.
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