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Temporal Evolution of Secondary Organic Aerosol Production from Volatile Chemical Products
ALBERT PRESTO, Mackenzie Humes, Rebecca Tanzer Gruener, Rishabh Shah, Allen Robinson, Neil Donahue, Carnegie Mellon University
Abstract Number: 52
Working Group: Missing contributors to SOA: The Role of Volatile Chemical Products (VCPS)
Abstract
One of the key distinctions between volatile chemical products (VCPs) and traditional combustion sources is that the magnitude and composition of VCP emissions can evolve over time. Chemical transport models can reasonably assume that vehicles and power plants have consistent (or at least predictable) fuel-based emission factors (e.g., g-pollutant per kg-fuel). Activity based emission factors are less certain for evaporative emissions from VCPs such as paints, coatings, and sealants that are applied as a liquid and have solvent(s) that evaporate over time. In this study, we monitored the evolution of organic compound (I/S/VOC) emissions from paint samples and quantified secondary organic aerosol (SOA) formation and composition over time.
We painted a 1 square meter board with several paints (e.g., interior latex paint, spray paint) and characterized I/S/VOC emissions with a PTR-MS and sorbent tubes analyzed via GC-MS. We used an oxidation flow reactor to generate SOA from the paint emissions. In each experiment, the board was painted, and concentrations monitored until they returned to background levels. We hypothesized that the paint would act as a long-term source of IVOC and SVOC compounds, and that SOA formation would persist for days to weeks after painting. Instead, the results are consistent with the painting acting as a one-time emissions event followed by dilution of the emitted vapors. Both vapor concentrations and SOA formation in the OFR return to background levels within ~6-8 hours, consistent with the dilution rate in the room where experiments were conducted. The SOA formation experiments will be supplemented with emissions tests using a flux chamber to verify that the bulk of SOA-forming vapors are emitted quickly.