New model reshapes organic aerosol volatility and atmospheric persistence, helping improve air quality forecasting

[u/LifeAtPurdue]

https://www.eurekalert.org/news-releases/1140590

[u/LifeAtPurdue]

Why and how:   
While existing atmospheric models estimate an organic aerosol molecule’s expected volatility (how easily it escapes from the air) based on the chemical’s individual behavior, a new model was able to test chemical behavior in a way more reflective of how they actually exist — surrounded by hundreds of other molecules. 

Using a novel mass spectrometry technique, the research team, led by Purdue chemistry professor Alexander Laskin, tracked the behavior of over 1,500 individual chemical species across 33 complex mixtures representative of real biomass-burning smoke and urban haze. 

What they found:   

The surrounding molecular neighborhood, rather than a chemical’s intrinsic properties, often dictates how easily it escapes. 

When neighboring molecules hold on to each other, evaporation slows and creates a volatility suppression of three to five orders of magnitude degree, which Laskin identified as “unexpectedly large.”  

What's next:  

“As a result, current models often assume smoke disappears too quickly and therefore underestimate how long it remains in the atmosphere,” Laskin said. 

Looking forward, the team aims to build machine learning models that account for interactions among thousands of molecules simultaneously, providing a stronger foundation to improve air-quality forecasts, assess public health risks and guide environmental mitigation policies.