A new scientific study has revealed that airborne dust particles play a much bigger role in air pollution and climate change than previously thought.
The research shows that large dust particles in the atmosphere can host chemical reactions leading to the formation of secondary organic aerosols (SOA), especially during dust storms.
SOA are tiny particles that form when gases from plants, vehicles, and industrial activities react in the atmosphere. These particles affect air quality and influence climate by affecting how much sunlight reaches Earth’s surface or how clouds form.
These large dust particles were previously considered incapable of hosting chemical reactions and that SOA mainly form in very small, water-containing particles or inside cloud droplets, but this new research challenges that view.
The scientists, from a number a countries including China, Japan and the UK, found that during dust events, more than 50% of the water-soluble organic carbon (WSOC) – which is mostly SOA – was found in these larger dust particles.
Even on days without major dust events, 25–51% of the WSOC was still in large particles.
It was seen that as the dust particles age while travelling through the atmosphere, they can collect coatings made from other substances, the key example here being calcium nitrate, which absorbs water from the air.
Once that happens, these large particles contain a thin layer of moisture, even if they’re not in a cloud. This liquid coating makes it possible for chemical reactions to take place on the surface of the particle, a process known as aqueous-phase chemistry.
Using microscopic analysis with global-scale computer modeling, the team found that these dust-driven reactions could account for up to two thirds of total SOA in some of the world’s dustiest regions, from North Africa to East Asia, considerably more than previously thought.
This discovery suggests that dust particles are not just passive carriers of pollution, but active players in atmospheric chemistry.
Co-lead author Professor Zongbo Shi from the University of Birmingham said: ‘This discovery marks a major advance in understanding the chemistry of secondary organic aerosols. We’ve found that water-containing aged dust can act like a sponge and a reactor—absorbing gaseous pollutants and transforming them into particles that affect our health and the climate.
‘This study sheds light on a key chapter in atmospheric chemistry but also reveals that the Earth’s natural dust storms have a far more complex and impactful role in our air quality than previously known. It underscores the importance of including these new chemical pathways in climate and air quality models.’
Dr. Akinori Ito from the Japan Agency for Marine-Earth Science and Technology (JAMSTEC) added: ‘Unravelling the ‘black box’ of surface reactions on wet dust particles is key to expanding the current boundaries of knowledge for accurately assessing aerosol impacts on climate and the environment.’
The full research can be accessed here.
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