Smog Chamber


The PSI Simulation Chamber for Atmospheric Chemistry (PSI-SCAC) is a medium sized indoor chamber. It is a tool to investigate chemical and physical processes related to air pollution under controlled conditions. We perform studies on oxidation mechanisms of gaseous pollutants, particle nucleation and secondary organic aerosol formation and ageing. Specific projects and questions addressed so far and at present include:
  • Investigation of oligomer formation in SOA
  • Determination of SOA yields from various precursor compounds
  • Investigation of the influence of organics and sulfuric acid on nucleation
  • Investigation of cloud forming potential of SOA
  • Intercomparison of instruments
  • Investigation of composition, gas/particle partitioning and volatility of SOA
  • Evaluation of photochemical mechanisms
  • Investigation of SOA formation from diesel, wood burning and other anthropogenic emission sources

Technical Description

The chamber is a 27-m3 (3×3×3 m) flexible bag made of 125 μm Teflon® fluorocarbon film (FEP). The bag is suspended in a temperature controlled wooden enclosure having dimension 4×5×4 m (L×W×H). Temperature can be stabilized to 1°C within the range of 17 to 25 °C. Four xenon arc lamps and/or a bank of 80 black lights can be used as light source.

Purified air is supplied by an AADCO (737-250 series, AADCO Instruments, Inc., USA) pure air generation system. Gaseous components (NO, NO2, gaseous organic compounds) can be delivered to the smog chamber. An ozone generator can provide ozone levels from ppb to ppm concentrations in the chamber. The chamber can be humidified with ultrapure water up to 80 %RH. A particle generation system is available for seed particle experiments. Three manifolds (inlet and outlet) made of stainless steel and Teflon® allow for easy installation of additional inputs and sampling lines.

The smog chamber is equipped with a fixed set of instruments which are regularly operated. Additionally, there are many special state of the art instruments of our own which are available for specific measurement campaigns.

For a detailed description see: Paulsen, D., J. Dommen, M. Kalberer, A.S.H. Prévôt, R. Richter, M. Sax, M. Steinbacher, E. Weingartner, and U. Baltensperger; Secondary Organic Aerosol Formation by Irradiation of 1,3,5-Trimethylbenzene-NOx-H2O in a New Reaction Chamber for Atmospheric Chemistry and Physics, Environ. Sci. Technol. 39, 2668-2678 (2005).

Transnational Access

Our smog chamber is partner of the “Infrastructure” program EUROCHAMP-2020 (Integration of European Simulation Chambers for Investigating Atmospheric Processes). This program supports researchers accessing state-of-the-art smog chamber facilities in Europe including ours. EUROCHAMP-2020 offers opportunities to researchers to bring their instruments and expertise to various simulation chambers for measurement campaigns and instrument testing. Details on this "Trans National Access" program can be found here.


More than 60 papers have been published from smog chamber experiments: see Publication list