Air Quality

Air quality research group studies reactive compounds in the atmosphere; their sources, concentrations and impacts on atmospheric chemistry.

Figure 1: Emission measurements of organic compounds (e.g. terpenes)

Organic compounds

Main sources of volatile organic compounds (VOCs) are traffic, wood and fossil fuel combustion, industrial processes and vegetation. Forests are a major source of VOCs in Finland. In the air these compounds participate in ozone formation. In addition to this they have a significant role in formation and growth of new particles. In our group we study VOC emissions (Figure 1) and their effects on atmospheric chemistry.

Inorganic compounds

In the air inorganic gases participate also in new particle and cloud formation. Therefore it is important to study the sources and concentrations of these gases together with the chemical composition of the formed particles. Figure 2  shows typical inorganic gas concentrations in a boreal forest (Hyytiälä).

Figure 2: Diurnal variation of concentrations of inorganic gases (ammonia, nitric acid and nitrous acid) in summer in a boreal forest in Hyytiälä, Finland.


We also study the total reactivity of the atmosphere. By measuring individual compounds together with total reactivity, it is possible to find out how much of the reactive compounds are missing (Figure 3). New compounds are identified in the situations in which the share of the unknown reactivity is high and new chromatographic methods for measuring these unknown compounds are developed.

Figure 3. Total hydroxyl radical (OH) reactivity in the air

Measurement methods

We use in situ gas chromatographs (GCs) for measurements of volatile organic compounds and in situ ion chromatographs (ICs) for measurements of inorganic gases and particles. We have also combined in situ ion chromatographs to a mass spectrometer for the measurements of more polar and less volatile organic compounds from gases and particles. With these in situ chromatographs it is possible to study rapid variations in concentrations, sources and atmospheric chemistry. For measurements of hydroxyl radical reactivity we use the comparative reactivity method (CRM).

Figure 4: In situ ion chromatograph (MARGA) connected to a mass spectrometer.