Quantification of cooking organic aerosol in the indoor environment using aerodyne aerosol mass spectrometers

• Published in: Aerosol science and technology Vol. 55; no. 10; pp. 1099 - 1114
• Main Authors: Katz, Erin F., Guo, Hongyu, Campuzano-Jost, Pedro, Day, Douglas A., Brown, Wyatt L., Boedicker, Erin, Pothier, Matson, Lunderberg, David M., Patel, Sameer, Patel, Kanan, Hayes, Patrick L., Avery, Anita, Hildebrandt Ruiz, Lea, Goldstein, Allen H., Vance, Marina E., Farmer, Delphine K., Jimenez, Jose L., DeCarlo, Peter F.
• Format: Journal Article
• Language: English
• Published: New York Taylor & Francis 03.10.2021; Taylor & Francis Ltd
• Subjects: Aerosol composition; Aerosols; Air sampling; Composition; Cooking; Indoor air quality; Indoor environments; Ionization; Jim Smith; Mass spectrometers; Mass spectrometry; Sampling; Spectrometers
• ISSN: 0278-6826; 1521-7388
• DOI: 10.1080/02786826.2021.1931013

The Aerodyne aerosol mass spectrometer (AMS) is used extensively to study the composition of non-refractory submicron aerosol composition during atmospheric field studies. During two recent studies of indoor environments, HOMEChem and ATHLETIC, the default ambient organic aerosol AMS quantification parameters resulted in a large discrepancy with co-located instruments while sampling cooking organic aerosol (COA). Instruments agreed within uncertainty estimates during all other sampling periods. Assuming a collection efficiency (CE) of unity, adjustments to the AMS relative ionization efficiency (RIE) were required to reach agreement with co-located instruments. The range of RIE COA observed (ATHLETIC: RIE COA  = 4.26-4.96, HOMEChem: RIE COA  = 4.70-6.50) was consistent with RIE measured in the laboratory for cooking-specific molecules. These results agree with prior AMS studies which have indicated that more oxidized outdoor ambient organic aerosol has a relatively constant RIE of 1.4 ± 0.3 while more reduced organics have higher RIE. The applicability of a higher RIE was considered for two ambient datasets, and agreement between the AMS and co-located instruments improved when an increased response factor (RIE CE) was applied to positive matrix factorization-derived primary organic aerosol (POA). Based on the observations presented here and the literature, we recommend AMS users consider applying RIE COA =4.2 to source and indoor studies of COA and evaluate a higher POA response factor of the order of ∼1.5 in outdoor studies at urban background sites, and ∼2 at sites impacted by fresh sources. This study aims to improve AMS quantification methodology for reduced POA and highlights the importance of careful intercomparisons in field studies.