Air pollutants, such as particulate matter and nitrogen oxides, are released into the air by – among other things – road traffic, agriculture and industry. These substances contribute to poorer air quality. They enter the body through inhalation, leading to various health effects, such as cardiovascular and respiratory diseases. Moreover, people exposed to air pollution may be more susceptible to respiratory infections. 

More hospital admissions and deaths due to poor air quality

In some regions, the air quality is worse than average. This may be due to high traffic volumes, industrial activities or intensive livestock farming. SARS-CoV-2 spreads from person to person through direct contact, coughing and sneezing. Air pollution does not play a direct role in the process of spreading. However, this study shows that people who live in areas with relatively poorer air quality are more likely to become infected with SARS-CoV-2. Moreover, more people end up in hospital or die due to more severe symptoms. Researchers looked at the first year of the epidemic, when people had not yet been vaccinated.

For example: in the period to 1 February 2021, around 22,500 people died from COVID-19. In the regions where the air quality was worse than average in the Netherlands, a total of 400 to 800 deaths could have been prevented if the air had been as clean as average. The cleaner the air, the greater the preventive effect.

Temporarily poorer air quality 

Even when the air quality in the living environment is lower only for a short period, more people end up in hospital and die due to COVID-19. Air quality varies greatly from day to day. This is due to the weather and temporarily higher (or lower) emissions from various sources.  

Sources of particulate matter

Especially at the beginning of the COVID-19 pandemic, people in several regions had questions about the impact of air pollution on the number of people who became infected with SARS-CoV-2. For this reason, RIVM studied the contributions of several major sources of particulate matter in the Netherlands, such as livestock farming, road traffic and industry. In addition, the composition of particulate matter and therefore its harmfulness differs per source.

The study shows that particulate matter emissions from livestock farming affect both the risk of infection and severity of disease. The researchers also found that particulate matter emissions from road traffic have a greater effect on the severity of disease, but less of an effect on the risk of infection with SARS-CoV-2. They found no specific influence on the risk of infection with SARS-CoV-2 or the severity of the disease for particulate matter emissions from industry. 

Improving air quality in the Netherlands

The study confirms that poorer air quality can lead to respiratory diseases, in this case also COVID-19. The results therefore highlight the importance of clean(er) air in the Netherlands. This will have a positive impact on public health in general. Cleaner air cannot prevent a future respiratory disease epidemic. However, cleaner air can reduce the harmful effects of an epidemic. 

RIVM conducted this study together with Utrecht University, Wageningen Bioveterinary Research, and the Netherlands Municipal Public Health Services and Medical Assistance in Accidents and Disasters.