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Keywords:

  • Indoor SOA;
  • d-Limonene;
  • Ozone;
  • Hydroxyl radical;
  • Aerosol mass fraction;
  • Yield

Abstract

Indoor secondary organic aerosol (SOA) formation may contribute to particle concentrations within residences, but little systematic work has investigated its magnitude or the determinants of its formation. This work uses a time-averaged modeling approach to predict the indoor SOA mass formed in residences due to the oxidation of 66 reactive organic compounds by ozone or the hydroxyl radical, parameterizing SOA formation with the aerosol mass fraction. Other organic and inorganic aerosols owing to outdoor and indoor sources were also predicted. Model inputs were represented as distributions within a Monte Carlo analysis, so that result distributions and sensitivity of results to inputs could be quantified, using a dataset developed from the study of Relationships between Indoor, Outdoor and Personal Air and other sources. SOA comprised a large amount of indoor organic and total fine particles for a subset of the results (e.g., >47% of indoor organic and >30% of fine aerosol for 10% of the modeled cases), but was often a small fraction. The sensitivity analysis revealed that SOA formation is driven by high terpene emission rates (particularly by d-limonene) and outdoor ozone, along with low air exchange and ozone and particle deposition rates.