The link between air pollution and COVID-19 deaths

Residents in New Delhi and Seoul, two of the world's most polluted cities, are finding some relief in the pandemic; they have enjoyed drops in the levels of airborne particulate matter of 60% and 54% respectively, against this time last year.

“It’s positively alpine,” said one Delhi resident. Cleaner air is always welcome news to urban populations; never more so, perhaps, than in the light of new research that finds people with long-term exposure to unhealthy levels of air pollution are now at greater risk of dying from COVID-19.

A recent study published in the journal Science of the Total Environment has found that long-term exposure to air pollution may be “one of the most important contributors to fatalities caused by the COVID-19 virus” around the world.

The study looked at COVID-19 deaths in four of the countries that have been hit hardest by the virus – Germany, France, Italy and Spain – and found that 78% had occurred in just five regions in northern Italy and Spain. These regions, the study notes, have among Europe's highest concentrations of nitrogen dioxide (NO2), a pollutant harmful to human respiratory systems, while their geography means these areas also suffer from downward air pressure, which can prevent the dispersal of airborne pollutants.

Italy’s worst-affected region has been Lombardy, which – with Milan as its capital – has recorded almost half of Italy’s total number of fatalities. Along with Piedmont, Emilia Romagna and Veneto, the Lombardy region sits in the Po Valley, which is ringed by mountains that cause this downward air pressure. In Spain, the worst-affected area has been the Madrid administrative region, which – as the study points out – is similarly surrounded by mountains.

As the following graph shows, there is a strong correlation between levels of NO2 and deaths associated with COVID-19:

As the study’s authors put it: “Poisoning our environment means poisoning our own body, and when [our body] experiences chronic respiratory stress, its ability to defend itself from infections is limited.”

Another recent study by Harvard University has generated similar findings. An analysis of 3,080 US counties found that even a small increase in long-term exposure to air pollution could have a significant effect on the severity of COVID-19 symptoms. It posits that lowering the average amount of airborne particulate matter in Manhattan by just one microgram over the past 20 years could have led to 248 fewer deaths from the disease in the borough to-date.

As well as weakening our respiratory systems and making us more susceptible to COVID-19, air pollution might also be functioning as a vector – that is, as a method of transmission for the virus. Scientists in Italy have detected coronavirus on particles of air pollution, which could, they believe, help the virus spread further. These findings are preliminary, however, and it is not yet known whether the virus remains viable after hitching a ride on pollution particles, or whether it can do so in sufficient amounts to cause infection.