This could potentially change how long the particles remain in the atmosphere, according to research led by the University of Birmingham. The team, involving researchers from the University of Birmingham, the University of Bath, Diamond Light Source and experts from CLF, found pollutants that form nanostructures could absorb substantially more water than simple models had previously suggested. Taking on water means the droplets become heavier and will eventually be removed from the atmosphere when they fall as rain.
Collaborating in this experiment was the CLF's Dr Andy Ward, who brings with him a wealth of knowledge of using Octopus laser technology to study a variety of aerosols related to health and the environment, and worked with this team on multiple related experiments prior to his appointment as the new head of the CLF's Lasers for Science Division (see
article in 2020 and
article in 2023).
The team used facilities at Diamond Light Source to study the water uptake of oleic acid, a molecule commonly found in emissions from cooking and spray from the ocean’s surface. They used a combination of two techniques - a Raman spectroscopy laser provided by the CLF's Dr Andy Ward to understand the chemistry, and Small-Angle X-ray Scattering (SAXS) at Diamond's I22 beamline to see the structures that formed. With this information, they charted the relationship between the structure inside the particle and both its ability to absorb water and its reactivity.
The team also studied changes in the structures of polluting particles caused by changes in humidity. They showed that as molecules react with ozone in the atmosphere and break down, they can also reform into different 3-D structures with varying abilities to absorb water and react with other chemicals. The findings, published in Atmospheric Chemistry and Physics, suggest these combined effects work to keep Oleic acid particles circulating in the atmosphere for longer.
As we develop our understanding of how these particles behave in the atmosphere, we will be able to design more sophisticated strategies to control air pollution.
Professor Christian Pfrang, School of Geography, Earth and Environmental Sciences said:
“As we develop our understanding of how these particles behave in the atmosphere, we will be able to design more sophisticated strategies for the control of air pollution,” said lead researcher Professor Christian Pfrang. “For example, protecting harmful emissions from degrading in the atmosphere could allow them to travel and disperse further through the atmosphere, thus substantially increasing the pollutant’s reach.”
He added:
“Our results show that aerosols exist in a really dynamic state, with complex structures being formed as well as being destroyed. Each of these states allows polluting molecules to linger in the atmosphere for longer. To reduce exposure to pollutants from cooking, people should consider making more use of extractor fans and ensuring that kitchens are well ventilated to allow aerosol particles to escape rapidly.”
