A new study has found that prolonged exposure to air pollution could increase the risk of developing serious Covid-19 symptoms that require hospitalization or intensive care treatment. The study, which included over 4.6 million adults, found that exposure to nitrogen dioxide, which is released from vehicle emissions, power plants and construction equipment, was especially dangerous. Nitrogen oxide was associated with a 42% increase in hospital admissions after a Covid-19 diagnosis, while exposure to fine particulate matter was linked to a 19% higher increase in hospital admissions, according to the study. The researchers also found that black carbon, a pollutant produced by wood cook stoves, diesel engines, wildfires, and incomplete combustion of coal, oil and gas, was associated with a 6% increase in Covid-19 deaths.
The study used data from the Catalan public health system to gain access to Covid-19 surveillance data and hospital admissions and discharges. The researchers then correlated this with air pollution data from Spanish monitoring networks. The study included participants from both urban and rural areas with individual-level data on air pollution exposures. The researchers suggest that air pollution exposure could increase people’s risk of developing co-morbidities like heart disease and hypertension, which could explain why it increases the risk of severe Covid-19 outcomes. They also note that air pollutants can impair lung defenses against infections and may impact immune defenses that are key to mitigating the coronavirus.
The researchers further pointed out that finding an association between ozone pollution and severe Covid-19 outcomes was more challenging to interpret compared to other types of air pollution. However, the study only evaluated the first year of the pandemic when there were no vaccines and variants of concern like Delta and Omicron. The study’s authors suggest that reducing air pollution levels could help to improve population health generally and severe acute respiratory infection specifically.