University of Helsinki
Air pollution is one of the major health risks in the 21st century. 91 % of the global population breath bad air. Around 7 million people die each year from air pollution, according to the WHO. And it is a rising problem: Air pollution is still growing, especially in the megacities around the globe.
How does air pollution form? What major sources influence air quality? Air pollution has many faces. Hazardous gases like ozone and nitrogen oxides can cause respiratory diseases. Fine particulate matter can penetrate deep into the human lungs and some of these small particles may even get into your bloodstream.
Particulate matter in the atmosphere are tiny liquid or solid droplets suspended in the air, so-called aerosols. Some of them are directly emitted in to the atmosphere like soot from combustion engines or dust particles during sand-storms. However, a major fraction of aerosols are of secondary origin, formed directly in the atmosphere from low volatile gases.
Secondary aerosols are important drivers for heavy smog events. However, these secondary processes are extremely complex. They involve heterogeneous chemistry, physical chemistry and fundamental physics. Moreover, ambient observations always are masked by meteorology. Thus, scientists around the world are trying to understand secondary aerosol formation and its impact on air quality.
NPF-PANDA, funded by the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie Actions, will look into New Particle Formation in Polluted Atmospheres. New Particle Formation (NPF) is frequently observed in the atmosphere throughout the globe. During this process, certain gas molecules start to stick at each other upon collisions. They form small molecular clusters, which can grow to larger aerosol particles. A phase transition of low volatile gases to liquid or solid particulate matter occurs. Usually, this process is observed during daytime. Particles smaller than 3 nanometer appear in the atmosphere and grow to sizes of 30-100 nanometer during the afternoon.
This process also occurs in heavily polluted environments, where it actually should not occur. Why? When the air is highly polluted a lot of pre-existing particles are already present, for example soot particles from combustion engines. The formed low volatile vapors would just condense onto those particles, not finding other vapor molecules fast enough to form clusters.
We need a better understanding of the nanocluster dynamics in order to find out how they form under polluted condistions. What grows these clusters? Are there any reasons why they won’t stick to the pre-existing particles?
New Particle Formation in Polluted Atmospheres by Nanocluster Dynamics Assessment (NPF-PANDA) will try to answer these questions and hence contribute to the question, what drives air pollution? How can we mitigate it?