Volume 32, Issue 7 e13075
ORIGINAL ARTICLE

Simulating indoor inorganic aerosols of outdoor origin with the inorganic aerosol thermodynamic equilibrium model ISORROPIA

Bryan C. Berman

Bryan C. Berman

Department of Civil, Architectural and Environmental Engineering, Drexel University, Philadelphia, Pennsylvania, USA

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Bryan E. Cummings

Bryan E. Cummings

Department of Civil, Architectural and Environmental Engineering, Drexel University, Philadelphia, Pennsylvania, USA

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Anita M. Avery

Anita M. Avery

Aerodyne Research, Inc., Billerica, Massachusetts, USA

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Peter F. DeCarlo

Peter F. DeCarlo

Department of Environmental Health and Engineering, Johns Hopkins University, Baltimore, Maryland, USA

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Shannon L. Capps

Corresponding Author

Shannon L. Capps

Department of Civil, Architectural and Environmental Engineering, Drexel University, Philadelphia, Pennsylvania, USA

Correspondence

Shannon L. Capps and Michael S. Waring, Department of Civil, Architectural and Environmental Engineering, Drexel University, Philadelphia, PA 19104, USA

Email: [email protected] and [email protected]

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Michael S. Waring

Corresponding Author

Michael S. Waring

Department of Civil, Architectural and Environmental Engineering, Drexel University, Philadelphia, Pennsylvania, USA

Correspondence

Shannon L. Capps and Michael S. Waring, Department of Civil, Architectural and Environmental Engineering, Drexel University, Philadelphia, PA 19104, USA

Email: [email protected] and [email protected]

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First published: 19 July 2022
Citations: 6

Abstract

Outdoor aerosols can transform and have their composition altered upon transport indoors. Herein, IMAGES, a platform that simulates indoor organic aerosol with the 2-dimensional volatility basis set (2D-VBS), was extended to incorporate the inorganic aerosol thermodynamic equilibrium model, ISORROPIA. The model performance was evaluated by comparing aerosol component predictions to indoor measurements from an aerosol mass spectrometer taken during the summer and winter seasons. Since ammonia was not measured in the validation dataset, outdoor ammonia was estimated from aerosol measurements using a novel pH-based algorithm, while nitric acid was held constant. Modeled indoor ammonia sources included temperature-based occupant and surface emissions. Sensitivity to the nitric acid indoor surface deposition rate β g , HNO 3 , g was explored by varying it in model runs, which did not affect modeled sulfate due to its non-volatile nature, though the fitting of a filter efficiency was required for good correlations of modeled sulfate with measurements in both seasons. Modeled summertime nitrate well-matched measured observations when β g , HNO 3 , g = 2.75 h 1 , but wintertime comparisons were poor, possibly due to missing thermodynamic processes within the heating, ventilating, and air-conditioning (HVAC) system. Ammonium was consistently overpredicted, potentially due to neglecting thirdhand smoke impacts observed in the field campaign, as well as HVAC impacts.

CONFLICT OF INTEREST

The authors have no conflicts of interest to declare.

DATA AVAILABILITY STATEMENT

The data that support the findings of this study are available from the corresponding authors upon reasonable request.

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