Air pollution ‘increases’ Covid risk, finds Italian study

Study indicates increased risk of COVID-19 for people living in highly polluted areas, although scientists warn that further work is needed to confirm causal link

People with long term exposure to even low levels of air pollution may have an increased risk of contracting COVID-19, according to a new study.

Scientists at the University of Insubria in northern Italy looked at 62,000 people aged 18 or over, in the city of Varese, and found a greater risk of developing COVID-19 for those living in very polluted areas.

Published in the journal of Occupational & Environmental Medicine, scientists found for every microgram rise in PM2.5, the chances of infection with COVID-19 rose by 5.1%, resulting in an extra 294 cases per 100,000 people per year.

The paper’s authors said: “Our findings provide the first solid empirical evidence for the hypothesised pathway linking long-term exposure to air pollution with the incidence of COVID-19 and deserve future generalisation in different contexts.

“Meanwhile, government efforts to further reduce air pollution levels can help to mitigate the public health burden of COVID-19.”

While an association has been discovered scientists warn further work is needed to confirm that this link is causal. Observational studies can be influenced and distorted by factors that have not been taken into account – in this case mobility, social interaction, humidity and temperature, and some comorbidities.

“A number of clues indicate air pollution is among the factors that may contribute to the spreading of COVID-19 infection and worsening of prognosis at a population level.”

However, the authors added: “Although correlation does not imply causation, a number of clues indicate air pollution [is] among the factors that may contribute to the spreading of COVID-19 infection and worsening of prognosis at a population level.”

Heidi Douglas-Osborn, policy and public affairs executive at the Chartered Institute of Environmental Health (CIEH), said: “CIEH along with its partner the Healthy Air Campaign, a coalition of charities, has long been calling for the introduction of strong targets for particulate matter, along with the 2005 World Health Organization’s air quality guidelines to be used as targets.

“This study has further highlighted that poor air quality is a serious concern, as it causes over 400,000 early deaths each year across the EU and the UK. Those with long-Covid may now also go on to be more vulnerable to pollutants in the air, as children, older people and people with chronic illnesses are.”

Since the start of the pandemic there have been attempts to understand why the incidence of infection differed across territories. Across Italy, the north has been most badly affected by COVID-19. Four out of the first five Italian regions with the most cases and deaths – from March to September 2021 – were in the Po valley, in the north.

The Po Valley, where the city of Varese is located, is also one of the most polluted areas in Europe. The EU Environmental Agency estimated that 95% of the 3.9m people in Europe living in areas where the main air pollution limits are exceeded live in Northern Italy.