High Indoor Coagulation/Condensation Sinks Can Suppress Nanocluster Aerosol Concentrations and New Particle Formation
Abstract
Sub-3 nm nanocluster aerosol (NCA) can originate from primary processes, such as combustion, or secondary processes, such as the oxidation of volatile organic compounds (VOCs). Recent research has demonstrated that common household activities can produce high number concentrations of NCA. An important loss mechanism for NCA and its low volatility gas-phase precursors is coagulation and condensation scavenging, respectively, by larger, pre-existing particles. Measurements are needed to understand how the persistence of indoor NCA is affected by coagulation and condensation sinks in indoor environments.
Field measurements of indoor NCA dynamics under variable natural and artificial coagulation/condensation sinks were conducted as part of the 2021 zEDGE-iRACE measurement campaign (zero Energy Design Guidance for Engineers-indoor Radical and Aerosol Chemistry Experiment) at Purdue University. NCA concentrations and size distributions were measured with a particle size magnifier - scanning mobility particle sizer (PSMPS). The PSMPS is a new aerosol instrument that integrates a short differential mobility analyzer (S-DMA), a diethylene glycol-based PSM, and a butanol-based condensation particle counter (CPC). Larger particles were measured with a long-SMPS and a wideband integrated bioaerosol sensor (WIBS). VOC concentrations were measured with a proton transfer reaction time-of-flight mass spectrometer (PTR-TOF-MS). A combination of indoor combustion and monoterpene ozonolysis experiments were performed; the former included boiling water and cooking on a gas stove and the use of candles and the latter included various terpene-based household products. The presence of large indoor coagulation/condensation sinks was found to suppress NCA number concentrations and new particle formation (NPF) events. Accumulation mode cooking aerosol emitted during cooking on a gas stove created natural coagulation sinks that scavenged combustion-generated NCA produced by the gas stove. This resulted in lower NCA number concentrations compared to boiling water on the gas stove. Similarly, artificial condensation sinks created by atomizing ammonium sulfate (modal diameter ~ 200 nm) significantly reduced indoor NCA concentrations during monoterpene ozonolysis, thereby inhibiting NPF.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2022
- Bibcode:
- 2022AGUFM.A36C..07B