A small rise in people’s long-term exposure to air pollution is associated with an 11% increase in deaths from Covid-19, research has found. Another recent study suggests that 15% of all Covid-19 deaths around the world are attributable to dirty air.
The available data only allows correlations to be established and further work is needed to confirm the connections, but the researchers said the evidence was now strong enough that levels of dirty air must be considered a key factor in handling coronavirus outbreaks.
The new analysis is based on research reported by the Guardian in April, which has now been reviewed by independent scientists and published in a prominent journal. The consideration of additional data and more factors that may also influence Covid-19 death rates refined the rise in deaths from 15% down to 11%.
Most scientists think it is very likely that air pollution increases the number and severity of Covid-19 cases. Breathing dirty air over years is already known to cause heart and lung disease, and these illnesses make coronavirus infections worse. Short-term exposure is also known to increase the risk of acute lung infections.
The gold-standard method for confirming the link between air pollution and Covid-19 would be to assess a large number of coronavirus patients on an individual level, so their age, smoking history and other details can be taken into account.
Such data, however, is not yet available so given the urgency of the pandemic researchers have used data on groups of people. This can be strongly indicative of a link, but may hide important individual factors.
There are now hundreds of group-level studies, although most have yet to be reviewed, said Prof Francesca Dominici at Harvard University, who led the new analysis.