Aerosols refer to any particles floating in air. They are small liquid droplets or solid particles, such as pollen.
“Pollen is at the large end of the scale, you can almost see it with the naked eye. We study much smaller particles, ones that can only be seen with accurate measuring equipment,” says Associate Professor Katrianne Lehtipalo from the Institute for Atmospheric and Earth System Research (INAR), University of Helsinki, and the Finnish Meteorological Institute.
Roughly half of all atmospheric aerosols originate in nature, such as the oceans, volcanic eruptions and wind lifting dust up into the air. The other half is made by humans: traffic and the incineration of various materials increase the number of particles in the atmosphere.
Basic research on molecules generates knowledge on air pollutants
Lehtipalo’s research topic is as current as can be, since particles have an impact on climate change – only we do not yet know their precise effects. For instance, reports by the Intergovernmental Panel on Climate Change (IPCC) demonstrate that the effect of aerosols on global warming is one of the most significant uncertainties associated with climate change.
Aerosols contribute to cloud formation and, thus, reflect solar radiation away from Earth. This way, aerosols have a cooling effect on the climate. They also do harm, as inhaling small particles is not healthy. In terms of good or bad air quality, the number of aerosol particles in the air is a factor.
“In Europe and, say, Helsinki, the air quality has improved in the past decades, while the global situation has worsened,” Lehtipalo notes.
Currently Lehtipalo is investigating the formation of aerosols on the molecular level. This constitutes basic research that scientists across the world only later get to utilise in applied research. Among other countries, the field is important in China and India where air pollution is a huge problem.
Lehtipalo perceives research as a gigantic jigsaw puzzle that scientists are collaboratively piecing together, with her personal efforts a small and specific piece of it.
“Improving climate models is the bigger picture, which I aim to promote through my own minor contributions.”
Finnish atmospheric research at the global top
The existence of aerosols has been known from the late 19th century. In Finland, Professor Markku Kulmala at the University of Helsinki started developing research in the field in the 1990s, investigating how compounds originating in forests form particles. Today, Kulmala is one of the most cited scientists specialised in atmospheric sciences, and his research has expanded to a group composed of roughly 200 researchers.
“We are at the global top in aerosol research,” says Lehtipalo, who is part of the group.
Not only is aerosol research highly international in nature, but it is also an exceptionally cross-disciplinary field. In addition to physicists, it involves chemists, meteorologists and environmental scientists.
Basic aerosol research is utilised in, for example, research on the climate and the health effects of particles, as well as in improving air quality. The basic research carried out in the field has served as a foundation for, among others, the measurement station network ACTRIS, while spinout companies based on research that manufacture and sell measuring devices have been founded in Finland, too.
There are aerosol particles almost everywhere, which generates application potential in a number of sectors. As applications are built on basic research, only after progress in basic research has been made does that potential become apparent.
“Once the edges of the jigsaw are completed, it’s easier to embark on a new area. Few people are able to just place a piece of the puzzle in the middle and claim that it belongs there,” says Lehtipalo, illustrating the progress of research, which is based on previously attained research-based knowledge.
Research is valuable in itself
Lehtipalo emphasises that research can have value in itself without having a specific goal. This is precisely the premise of basic research.
“We cannot currently know what research efforts benefit humanity the most a hundred or even ten years from now.
For instance, scientists who have previously carried out basic research on coronaviruses have now had the opportunity to apply their findings in an entirely new way.”
However, Lehtipalo thinks that valuing knowledge for knowledge’s sake does not exclude the potential instrumental value of science.
“People want knowledge with which to generate money, health, free time and other benefits for society,” Lehtipalo elaborates.
A research station network produces comparable data
A modicum of unpredictability is always inherent in research. Sometimes something revolutionary comes about, at other times nothing at all. In aerosol research, perseverance is key. At the moment, Lehtipalo is contributing to the establishment of a research station network where atmospheric particles are measured across Europe. The aim is to conduct measurements simultaneously using the same methods and equipment in order to produce comparable data. Once such efforts produce long time series, it becomes possible to compare, among other things, what takes place in the atmosphere during unexpected events – such as when air traffic is suspended due to a pandemic.
Lehtipalo believes that in the future, atmospheric research will increasingly focus on how to prepare for the effects of climate change.
“Still, we will also continue to need knowledge originating in basic research on the traits and behaviour of aerosol particles in the atmosphere.”