Modeling Indoor Inorganic Aerosol Concentrations During the ATHLETIC Campaign with IMAGES

Area of Science:

• Environmental Science
• Atmospheric Chemistry
• Indoor Air Quality

Background:

• Indoor environments host complex aerosol and gas dynamics.
• The ATHLETIC campaign collected data on indoor air composition in a gymnasium.
• Understanding indoor inorganic aerosol behavior is crucial for health and environmental assessments.

Purpose of the Study:

• To evaluate the performance of the Indoor Model of Aerosols, Gases, Emissions, and Surfaces (IMAGES) using real-world indoor air quality data.
• To assess the accuracy of the ISORROPIA thermodynamic equilibrium model in simulating indoor inorganic aerosol partitioning.
• To identify key parameters influencing indoor aerosol composition and model performance.

Main Methods:

• Utilized data from the 2018 ATHLETIC campaign conducted at the University of Colorado.
• Alternatingly measured inorganic particle and gas-phase species in a gym's supply duct and weight room.
• Employed the ISORROPIA model within IMAGES to estimate aerosol-gas partitioning, informed by occupancy data.

Main Results:

• Initial IMAGES model runs showed poor agreement with measured indoor inorganic aerosol concentrations.
• Lowering temperature and increasing relative humidity in the ISORROPIA model substantially improved agreement.
• The study suggests enhanced aerosol water content or non-equilibrium conditions may explain the improved model performance.

Conclusions:

• Simulating indoor inorganic aerosol dynamics with ISORROPIA requires careful parameterization, particularly regarding temperature and relative humidity.
• The findings highlight potential limitations of applying thermodynamic equilibrium models in dynamic indoor settings.
• Further experimental validation is necessary to refine the application of ISORROPIA for indoor air quality modeling.