The proportion of harmful substances in particulate matter is much higher than assumed
People breathing contaminated air over the course of years are at greater risk of developing numerous diseases. This is thought to be due to highly reactive components in particulate matter, which affect biological processes in the body. However, researchers from the University of Basel have now shown that precisely these components disappear within hours and that previous measurements therefore completely underestimate the quantities in which they are present.
31 March 2025 | Angelika Jacobs
From chronic respiratory problems to cardiovascular diseases, diabetes and dementia, health damage caused by particulate matter air pollution is wide-ranging and serious. The World Health Organization (WHO) estimates that over six million deaths a year are caused by increased exposure to particulate matter. The chemical composition of these tiny particles in the air, which come from a wide range of both anthropogenic and natural sources, is highly complex. Which particles trigger which reactions and long-term diseases in the body is the subject of intensive research.
This research focuses on particularly reactive components known to experts as oxygen radicals or reactive oxygen species. These compounds can oxidize biomolecules inside and on the surface of cells in the respiratory tract, damaging them and in turn triggering inflammatory responses that impact the entire body.
Experts previously collected the particular matter on filters and analyzed the particles following a delay of days or weeks. “Since these oxygen-containing radicals react with other molecules so quickly, they should be measured without delay,” says atmospheric scientist Professor Markus Kalberer, explaining the idea behind the study that he and his team recently published in Science Advances.
Measured from the air in real time
The team from the Department of Environmental Sciences has developed a new method for measuring particulate matter within seconds. This involves collecting the particles directly from the air in a liquid, where they come into contact with various chemicals. Within this solution, the oxygen radicals then react and produce quantifiable fluorescence signals.
Measurements taken with the new method reveal that 60% to 99% of oxygen radicals disappear within minutes or hours. Previous analyses of particulate matter based on filter deposition therefore delivered a distorted image. “However, since the measurement error in the case of delayed analysis isn’t constant, it’s not that possible to extrapolate from previous filter-based analyses,” says Kalberer. The real proportion of harmful substances in the particulate matter is, he says, significantly higher than previously assumed.
According to the atmospheric researcher, the principal challenge with the new method was to develop a measuring instrument that carried out chemical analyses autonomously and continuously under stable conditions not only in the laboratory but also during field measurements at a wide range of locations.
Different and stronger inflammatory responses
Moreover, further laboratory analyses with epithelial cells from the lungs provided evidence that, in particular, the short-lived, highly reactive components of particulate matter have a different effect than that of the particles analyzed using the previous, delayed measurements. The short-lived reactive components in particles triggered different and stronger inflammatory responses.
In a subsequent step, the measuring instrument will be further developed in order to obtain deeper insights into the composition and effects of particulate matter. Kalberer explains: “If we can measure the proportion of highly reactive, harmful components more accurately and reliably, it will also be possible to adopt better protective measures.”
Original publication
Steven J. Campbell et al.
Short-lived reactive components substantially contribute to particulate matter oxidative potential
Science Advances (2025), doi: 10.1126/sciadv.adp8100
