AAAR 34th Annual Conference
October 12 - October 16, 2015
Hyatt Regency
Minneapolis, Minnesota, USA
Abstract View
Source Emission Rates of Indoor Ultrafine Particles Considering Coagulation, Deposition, and Ventilation
DONGHYUN RIM, Lance Wallace, Andrew Persily, Jung-il Choi, Pennsylvania State University
Abstract Number: 176 Working Group: Aerosol Exposure
Abstract Human exposure to airborne ultrafine particles (UFP, < 100 nm) has been shown to have deleterious pulmonary, cardiovascular, and premature health effects. Indoor UFP emissions from combustion appliances and consumer products lead to elevated human exposure to UFP. The particles emitted from the sources undergo aerosol transformation processes such as coagulation and deposition. Coagulation effect can be significant and much larger than particle deposition during the source emission. However, few studies estimated indoor UFP source emission strengths by considering coagulation effects. The objective of this study is to characterize size-dependent emission strength indoor UFP sources by considering coagulation in addition to deposition and ventilation.
Experiments monitored size-resolved concentrations of UFP ranging from 2 nm to 100 nm using a Scanning Mobility Particle Sizer (SMPS) in a full-scale test house. Time-dependent particle size distribution was monitored for two indoor sources: a natural gas burner and a candle. Using the monitoring data of source emission and decay period, UFP source emission strength was determined based on an analytical model that considers coagulation in addition to deposition and ventilation based on the moment method of log-normal size distribution functions.
The results indicate that UFP source emission strength varies with source type and particle size. The results suggest that neglecting coagulation could largely underestimate the emission strength as coagulation accounts for the emission and initial decay period. Larger errors are observed with missing coagulation effect for smaller particles and higher concentrations. The discrepancy in estimate of source strength due to coagulation effect was observed up to factor of 10 or more. This result implies that previous studies on indoor UFP source strengths considering only deposition and ventilation might have underestimated the true values of UFP source strengths.