Aging and Transformation Chamber

Aging and Transformation Chamber

The transformation chamber at the ILMARI Research Unit is a batch reactor where the oxidizing environment, humidity, temperature, the amount of initial seed, and UV conditions are controlled. The chamber is designed for emission aging studies enabling the atmospherically relevant conditions in the experiments.

The chamber is located in an air-conditioned and temperature-controlled enclosure and it consists of a 29 m3 TeflonTM FEP bag mounted in a frame which has a movable top and a counterweight system to ensure the pressure control over the experiments. Normally, the chamber is kept at an overpressure of a few Pa, in order to minimize the inward flow of contaminants.

The clean air injected to the chamber is produced by an air purifier with methane reactors and humidified with ultrapure deionized water to the wanted humidity. The ozone production capacity in ILMARI is high enough to achieve also ozone concentrations of several ppm in the experiments and cleaning procedure. The temperature and relative humidity are measured in the middle of the chamber and gaseous components, such as ozone, oxides of nitrogen, sulphur dioxide, and carbon dioxide, are monitored continuously (see the list of measurement devices). In the emission experiments, the diluted emissions from combustion sources or selected precursor organics are injected to the chamber so that the wanted concentrations are achieved. The chamber is located in an air-conditioned enclosure, whose temperature can be controlled at room temperature within one degree of Celsius.

Photochemical reactions are initiated by ultraviolet radiation produced by blacklight lamps located in the sides of the chamber. Two types of lamps, with spectra centered at 350 nm and 340 nm, are used to produce radiation spectrum that corresponds the radiation conditions comparable to local atmospheric conditions. The chamber enclosure is coated with reflective aluminium blanket to maximize the irradiance in the chamber and to ensure an equal illumination. When dark aging is desired, oxidants, such as ozone, can be injected into the chamber.

Information on the chamber is also available at Eurochamp2020 web pages


Leskinen, A., Yli-Pirilä, P., Kuuspalo, K., Sippula, O., Jalava, P., Hirvonen, M.-R., Jokiniemi, J., Virtanen, A., Komppula, M., Lehtinen, K.E.J. (2015) Characterization and testing of a new environmental chamber. Atmos. Meas. Tech. 8, 2267-2278, doi:10.5194/amt-8-2267-2015

For more information, please contact Prof. Annele Virtanen, annele(at)