AAAR 37th Annual Conference October 14 - October 18, 2019 Oregon Convention Center Portland, Oregon, USA
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Indoor Particle Transformation Processes Due to Candle Burning
Su-Gwang Jeong, Lance Wallace, DONGHYUN RIM, Pennsylvania State University
Abstract Number: 108 Working Group: The Air We Breathe: Indoor Aerosol Sources and Chemistry
Abstract Human exposure to indoor ultrafine particles (UFP, < 100 nm) are associated with occupant activities such as cooking and using consumer products. One of the major indoor UFP sources is candle use. Indoor UFP exposure can significantly vary with aerosol transformation processes such as coagulation, deposition and ventilation, and such processes are influenced by building operating conditions. The objective of this study is to investigate the coagulation, deposition and decay rates of indoor UFP originated from three types of candles: tapered paraffin, scented soy candles in glass jars, and beeswax pillars. In this study, particle number, surface area, and mass distributions due to candle burning for 93 particle sizes from 2 to 64 nm were examined. The relative contributions of individual particle loss mechanisms (i.e., coagulation, deposition, and ventilation loss) were characterized using the coagulation model that considered Brownian motion with the Fuchs correction along with van der Waals and viscous forces. The results show that peak number, surface area, and mass concentrations occurred at particle sizes of < 3 nm, 20 nm, and 40 nm, respectively. Relative contributions of coagulation, deposition, and air exchange rates to the total particle losses were 65.4%, 34.3%, and 0.3% at a high concentration (i.e., 106 cm-3), while they are 17.4%, 80.9%, and 1.7% at a lower concentration (i.e., 3 × 104 cm-3), respectively. This result suggests that coagulation is a dominant particle loss mechanism when the total number concentration exceeds 105 cm-3, and it is still responsible for 20% particle loss at lower concentrations such as 4 × 104 cm-3. These results highlight the importance of coagulation in indoor nanoparticle dynamics due to candle burning.