A new international study, involving researchers from the Cyprus Institute, the Max Planck Institute for Chemistry and physicians from the University Hospital of Mainz in Germany, highlights the serious health effects associated with long-term exposure to ultrafine particles (UFPs), an atmospheric pollutant that remains largely outside systematic air quality monitoring to this day.
As part of the study, the researchers created the first high-resolution global map of exposure to this pollutant, with findings revealing that long-term exposure to ultrafine particles is associated with approximately two million premature deaths worldwide each year.
A pollutant that largely goes unnoticed
Ultrafine particles are extremely small, with a diameter of less than 100 nanometres, and originate mainly from combustion processes, such as those associated with road traffic, industry and energy production.
Due to their extremely small size, they can penetrate deep into the lungs and pass into the bloodstream. Long-term exposure to them has been linked to an increased risk of cardiovascular disease and other serious health effects.
Although they are a significant air pollutant, ultrafine particles are not covered by regulatory limits under the current European framework for air quality. At the same time, most scientific studies and air quality monitoring to date have focused mainly on fine particles PM₂.₅ and PM₁₀, meaning data on ultrafine particles remain limited.
First global assessment of exposure and health effects
The new study provides a global picture of the population's long-term exposure to ultrafine particles, mapping exposure on a global scale at one-kilometre resolution. In doing so, the researchers were able to more accurately estimate the pollutant's likely impact on public health.
According to the study's estimates, the approximately two million premature deaths linked to exposure to ultrafine particles correspond to around 5% of deaths from non-communicable diseases, with nearly half related to cardiovascular disease.
The highest concentrations are found mainly in areas with elevated emissions from human activity, such as road traffic, industry and energy production.
The study also examines the impact of possible measures to reduce the health effects of ultrafine particles. The researchers estimate that setting an annual limit of 5,000 particles per cubic centimetre of air could reduce global mortality linked to exposure to these particles by around 45%.
Based on these findings, the study's authors stress the need for a substantial reduction in emissions from combustion processes in cities, particularly from road traffic, industry and energy production, as well as for accelerating the transition to non-fossil energy sources. They also highlight the importance of incorporating ultrafine particles into systematic air quality monitoring, so that their long-term health effects can be better recorded.
As Dr Jos Lelieveld, Professor at the Cyprus Institute, Director Emeritus at the Max Planck Institute for Chemistry, and lead author of the study, explains: "Ultrafine particles remain a significant gap in air quality policy. Although they are present almost everywhere in our cities, they are not systematically monitored. Our study provides, for the first time, a global picture of exposure to these particles, their main sources and their health effects. This new data can help shape more effective policies to improve air quality and protect public health."
