Air pollution and COVID-19 are both well known in causing or exacerbating respiratory distress, and a new analysis suggests that the two factors may interact. As part of a series of reports from the IZA Institute of Labor Economics, researchers have found that regions in the Netherlands with higher air pollution have greater numbers of COVID-19 cases, hospitalizations, and deaths. However, they stress that the findings do not prove a causal relationship.
The Netherlands, home to more than 17 million people, has experienced more than 50,000 cases of COVID-19. The study compared air quality readings from 355 municipalities in the country, including data on nitrogen dioxide, sulfur dioxide, and fine particulate matter. The team found that areas that had even slightly higher pollutant levels tended to have more cases, hospitalizations, and deaths. The authors calculated that if the most polluted areas, which measured a 12.3 µg/m3 concentration of fine particulate matter, was halved, making it comparable to the 6.9 µg/m3 concentration of the least polluted regions, “our results suggest this would lead to 82 fewer disease cases, 24 fewer hospital admissions and 19 fewer deaths, purely as a result of the change in pollution,” they write for The Conversation.
“What I was struck by was this really was a strong relationship,” coauthor Matthew Cole, a professor of environmental economics at the University of Birmingham in the UK, tells The Guardian.
A previous preprint study in the United States found that just 1 µg/m3 more fine particulate matter in the air corresponded to 8 percent more COVID-19–related deaths. The new study found that in the Netherlands, for the same increase in fine particulates, the death rate was as much as 16 percent greater. The authors attribute the differences in the results to wide variances of population density within the US, which makes it difficult to average numbers across the country.
Previous analyses have examined a link between air pollution and COVID-19 in European countries and found a positive relationship between pollutants and death rate. This latest study on the Netherlands looked beyond the numbers themselves and more accurately corrected for spatial spillover, which previous studies have not done, including the proximity to international borders and the amount of traffic between countries, the locations of airports and the destinations they serve, and how coastal areas are shielded from many of those variables.
“As analyses of a possible link between air pollution and COVID-19 progress we are beginning to see much better studies emerge,” Frank Kelly, a professor at the school of public health at Imperial College London who was not involved in the study, tells The Guardian. “This new study appears to be the best to date.”