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Updated: May 19, 2026

Production and Measurement of Organic Particulate Matter in the Harvard Environmental Chamber
Published on: November 18, 2018
Aging of biogenic secondary organic aerosol via gas-phase OH radical reactions
Neil M Donahue1, Kaytlin M Henry, Thomas F Mentel
1Center for Atmospheric Particle Studies, Carnegie Mellon University, Pittsburgh, PA 15217, USA. nmd@andrew.cmu.edu
Abstract:
The Multiple Chamber Aerosol Chemical Aging Study (MUCHACHAS) tested the hypothesis that hydroxyl radical (OH) aging significantly increases the concentration of first-generation biogenic secondary organic aerosol (SOA). OH is the dominant atmospheric oxidant, and MUCHACHAS employed environmental chambers of very different designs, using multiple OH sources to explore a range of chemical conditions and potential sources of systematic error. We isolated the effect of OH aging, confirming our hypothesis while observing corresponding changes in SOA properties. The mass increases are consistent with an existing gap between global SOA sources and those predicted in models, and can be described by a mechanism suitable for implementation in those models.
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