Decreasing concentrations of inorganic particles in the atmosphere present new challenges for climate models
On Manhattan, in the heart of New York, more airborne hydrocarbons originate from cleaning products and cosmetics than from traffic. Because hydrocarbons form aerosols, it is reasonable to assume that personal care and cleaning products have already surpassed traffic as sources of air pollution.
"An island dominated by skyscrapers is naturally an extreme example, given its exceptionally high population density," notes Academy Professor .
Even so, this observation signals a wider change. As methods improve for capturing inorganic air pollutants such as soot, and electric alternatives increasingly supersede internal combustion engines, the share of inorganic pollutants in urban air will fall.
This is undoubtedly good news for air quality. For those modelling airborne particles, however, it creates new challenges.
"As the number of inorganic particles in the air falls, the number of organic particles rises in both relative and absolute terms," explains Vehkamäki. T his trend in urban environments reflects not only more urban greenery, but also the effects of climate change, which accelerate biological processes.
The shift in particle sources presents researchers with a new set of questions.
"For much of my career, I've looked at sulphuric acid and how it forms atmospheric aerosols, starting small and growing bigger. Even in this field, there's still plenty we don't know. When it comes to organic compounds, we're just getting started," states Vehkamäki.
One reason for this is the sheer number of organic compounds. Over 10,000 exist in urban air, and they react readily with each other.
Just two compounds can combine in 100 million ways, and three compounds give rise to a trillion possibilities. Clearly, new approaches are needed. This is Vehkamäki's focus during her five-year term as Academy Professor.
Her tools include AI, which enables faster simulation of various combinations, and high-precision measurements - 'tinkering' as she calls it.
"We measure particle formation in the lab under meticulously controlled conditions. We then tweak the parameters and measure again, repeating the cycle many times. The work is slow and repetitive, but immensely rewarding when it deepens our understanding."
"This trend in urban environments reflects not only more urban greenery, but also the effects of climate change, which accelerate biological processes."
Homepage of Computational Aerosol Physics can be found .
