Organic aerosols – such as those released in cooking – may stay in the atmosphere for several days because of nanostructures formed by fatty acids as they are released into the air, new research finds.

By identifying the processes that control how these aerosols are transformed in the atmosphere, scientists will be able to better understand and predict their impact on the environment and the climate.

Experts at the Universities of Bath and Birmingham have used instruments at the Diamond Light Source and the Central Laser Facility, both based at the Harwell Campus in Oxford, to probe the behaviour of thin films of oleic acid – an unsaturated fatty acid commonly released when cooking.

For the study, published in Atmospheric Chemistry and Physics, the researchers were able to analyse the particular molecular properties that control how rapidly aerosol emissions can be broken down in the atmosphere.

Then, using a theoretical model combined with experimental data, the team was able to predict the length of time aerosols generated from cooking may hang around in the environment.

These types of aerosols have long been associated with poor air quality in urban areas, but their impact on human-made climate change is hard to gauge. That is because of the diverse range of molecules found within aerosols and their varying interactions with the environment.

By identifying the nanostructure of molecules emitted during cooking that slows down the break-up of organic aerosols, it becomes possible to model how these molecules are transported and dispersed into the atmosphere.

Co-author Dr Adam Squires from the Department of Chemistry at Bath says: “We’re increasingly finding out how molecules like these fatty acids from cooking can organise themselves into bilayers and other regular shapes and stacks within aerosol droplets that float in the air, and how this completely changes how fast they degrade, how long they persist in the atmosphere, and how they affect pollution and weather.”

Lead author Dr Christian Pfrang, of the University of Birmingham’s School of Geography, Earth and Environmental Sciences, adds: “Cooking aerosols account for up to 10% of particulate matter (PM) emissions in the UK. Finding accurate ways to predict their behaviour will give us much more precise ways to also assess their contribution to climate change.”

This research was funded by the Natural Environment Research Council and the data was produced and analysed using the University of Birmingham’s BlueBEAR high performance computing service.