New Frontiers in Environmental Analysis: Atmospheric Alarms
As part of a new series featuring leaders in the field of environmental analysis, atmospheric aerosol expert Markku Kulmala shares his mission to set up thousands of environmental monitoring stations around the globe
| 7 min read | Interview
Credit: Supplied by Interviewee
Could you share more about your work in atmospheric science?
We operate on multiple levels – national, European, and global – and our work spans several areas: research, research infrastructures, knowledge transfer, education, policy, and innovation/industry-related activities. We work across all of these pillars, focusing on building comprehensive research stations that gather open data to address major environmental challenges, such as climate change and air quality, as well as biodiversity loss, water and food supply and circulation. We've established research stations in Finland and expanded to places like China, India, Estonia, South Africa, and beyond. We continuously collect data from these stations, analyze it – using e.g. atmospheric pressure interface mass spectrometry (APi-MS), especially time-of-flight (TOF) instruments. These instruments allow us to measure different compounds and clusters of gas molecules. We can generate a wide range of spectra, capturing the detailed composition of gasses and aerosols in the atmosphere.
The goal is to establish about 1,000 stations worldwide, in various ecosystems, including urban areas. Right now, we have about 10, so there’s still a long way to go! And though 1,000 stations would be ideal, even 200 or 300 would prove to be very useful.
We also aim to integrate our findings into education. For instance, every October and March, we host autumn and winter schools at our station in Hyytiälä, southern Finland. During these sessions, we analyze the data we’ve collected with 35–45 students from various countries who participate in these hands-on data analysis courses.
What measurements are you collecting?
We measure air quality directly from the atmosphere. We collect data from the soil, including temperature and humidity profiles. We measure ecosystem functions, such as photosynthesis and gas exchange between tree needles and the atmosphere. We also track tree growth by monitoring diameter and other functional aspects. We measure aerosol concentrations in the air, and we record fluxes – meaning we monitor changes of CO₂ and other greenhouse gasses. We even track various types of radiation, including solar radiation, cosmic radiation, and radon emissions from the soil. As you can see, we cover a broad range of measurements.
What have you observed happening in the atmosphere?
Let me give you a comparison between a major city like Beijing and our background station in Finland, at Hyytiälä. Hyytiälä isn’t the cleanest place on the planet, but it is on the cleaner end of the spectrum, whereas Beijing is much more polluted. Interestingly, some atmospheric processes are quite similar between these locations. For instance, the growth rate of newly formed aerosol particles – about 4–6 nm per hour – is roughly the same in both places. However, the rate at which new particles (around 1.5 nm in size) are produced is about 100 times higher in Beijing than in Hyytiälä.
Moreover, measuring so many different variables with so many different instruments is throwing up a number of surprises. During the COVID-19 lockdown, for example, we observed that in Beijing, nitrogen oxides (NOx) and particle mass concentrations decreased, but ozone levels and particle numbers increased. Surprisingly, the overall particle mass only went slightly down, remaining almost the same before, during, and after the lockdown.
At our station in Hyytiälä, we’ve observed how increased CO₂ levels lead to more photosynthesis, which in turn emits volatile organic compounds (VOCs) like monoterpenes. These VOCs undergo chemical reactions in the atmosphere, producing low-volatile highly oxidized organic compounds that contribute to new aerosol particle formation. These particles can grow to become cloud condensation nuclei, which influence cloud droplets and, ultimately, precipitation. However, when there are more aerosol particles, clouds live longer, become thicker, and reflect more sunlight. On the other the more aerosol particles we have the more the amount of diffuse solar radiation is enhanced, which penetrates radiation deeper into the ecosystem, further enhancing photosynthesis. It’s a fascinating feedback loop with significant implications for both weather and climate.
What long-term trends are you seeing?
We’ve observed changes such as a decrease in SO₂ concentrations, both in Beijing and Hyytiälä. We also see how factors like population growth and land-use changes are impacting air quality and climate; in turn, we see how climate changes are influencing processes like photosynthesis. Though our data doesn’t span hundreds of years, the data we have – over decades – allows us to clearly see these changes at various time scales.
In terms of spatial scales, some of our measurements are highly localized, covering just a few centimeters. But others, like absolute CO₂ concentration, have a much larger footprint – around 1,000 kilometers. This means we’re able to observe effects over different time frames and spatial extents.
Are you aware of any initiatives to improve atmospheric conditions?
It depends on what we mean by "improving the atmosphere." Of course, there are air quality regulations and initiatives, particularly in countries like India, China, and other large cities that aim to improve air quality due to the high number of deaths linked to air pollution. Reducing direct emissions of particulate matter is relatively straightforward. The more challenging issue today is related to secondary aerosol particles, which dominate both global and regional air pollution. These particles form in the atmosphere through chemical reactions – what I call "airborne production of particulate matter." Currently, around 80–90 percent of particulate mass is generated this way. Reducing this type of pollution is much harder because it involves understanding the complex, nonlinear atmospheric chemistry behind it. We need to gather and analyze large amounts of data to fully understand the atmospheric processes and possibly discover new oxidation pathways. This is not only a fascinating area of atmospheric chemistry from an analytical point of view, but also a critical one in terms of improving air quality.
So analytical chemists must play an important role…
Absolutely. Analytical chemists play a crucial role! We constantly need to improve our methods for making in situ observations in the atmosphere, especially when dealing with very low concentrations. Many important atmospheric compounds, especially in the gas phase, are present at extremely low levels – often in the parts per quadrillion (PPQ) range, with as few as 1,000 or 10,000 molecules per cubic centimeter, sometimes even less. This makes it incredibly challenging to push the detection limits of techniques, such as API-MS, low enough. Additionally, we need analytical chemistry expertise to help us properly calibrate these measurements. Though we understand some of the basics, the need for better calibration methods and possibly developing standards for these measurements is crucial. And that requires specific expertise in analytical techniques.
Considering the effects of the current air constitution, what are the main issues we’re facing today?
The most pressing issue is climate change. We have too much CO₂, methane, and other greenhouse gasses in the atmosphere. In large cities, air pollution is still a major problem. It's estimated that between 4 and 8 million people globally die prematurely every year because of air pollution. We need to understand how our atmosphere is changing to tackle this significant number.
One example of a non-linear effect in atmospheric chemistry is when reducing NOx, it can sometimes increase the production of ozone, which in turn can enhance particulate matter (PM 2.5) and particle numbers. We also need to understand feedback loops and other complex interactions in the atmosphere. I often tell my students that they will have plenty of work to do in this field until they retire!
Some governments don’t seem very interested in climate change or air pollution...
It doesn’t matter if some governments aren’t interested in climate change – this isn’t a matter of opinion or something that can be voted on. The situation is getting bad enough that everyone will have to take an interest. The markets will also push this forward, both in terms of climate and air pollution. This isn’t a “democracy question.” We’re seeing more heat, weather extremes, more pollution, and more people are suffering or dying as a result. Governments will be forced to pay attention. The industrial and economic sectors will also get involved because people demand sustainable climate and clean air. It doesn’t matter if some governments are uninterested today, because in 10 years, everyone will have to address these issues – or we’ll have miraculously solved them, which I don’t think will happen any time soon. And that is why I’m confident we have a lot of work ahead, and our students have a strong future in this field.
Markku Kulmala is Professor of Aerosol and Environmental Physics at the University of Helsinki, Finland
