Real-Time Evaluation of VOC Emission Factors and Intake Fractions for Scented Wax Products Using PTR-TOF-MS
JIANGHUI LIU, Jinglin Jiang, Satya Patra, Xiaosu Ding, Jordan Cross, Brandon E. Boor, Nusrat Jung,
Purdue University Abstract Number: 489
Working Group: Indoor Aerosols
AbstractScented wax products, such as candles and wax warmers, are a sub-class of volatile chemical products (VCPs) that are commonly used in residential buildings in the U.S. Significant quantities of wax are manufactured for use in such products, with more than 10
8 kg of wax used for candle production alone in the U.S. each year. As many candles and wax warmers are intentionally fragranced to produce pleasant aromas and indoor smellscapes for occupants, scented wax products may represent an important source of volatile organic compounds (VOCs) to indoor and urban atmospheres. The aim of this study is to evaluate VOC emission factors (EFs) and intake fractions (iFs) for scented wax products to better understand their impact on atmospheric chemistry and chemical exposures. Full-scale indoor emission experiments were conducted in the Purdue zero Energy Design Guidance for Engineers (zEDGE) Tiny House using a variety of scented candles (
n=5) and wax warmers (
n=14) under different outdoor air exchange rates (AERs). VOC concentrations were measured in real-time (1 Hz) using a proton transfer reaction time-of-flight mass spectrometer (PTR-TOF-MS) with hydronium (H
3O
+) as the reagent ion. A material balance model was used to estimate speciated EFs and iFs during indoor use of scented wax products. PTR-TOF-MS measurements revealed that scented candles and wax warmers emit a variety of monoterpenes (C
10H
16) and monoterpenoids (C
10H
14O, C
10H
16O, C
10H
18O, C
10H
20O), among other VOCs, with concentrations in the range of 10
-1 to 10
2 ppb. Monoterpene EFs were much greater for wax warmers (C
10H
16 EFs ~ 10
2 mg per g wax consumed) compared to scented candles (C
10H
16 EFs ~ 10
-1 to 10
0 mg per g wax consumed). Thus, wax warmers are more heavily fragranced compared to scented candles. VOC iFs were similar between the two (C
10H
16 iFs ~ 10
3 ppm) and increased with decreasing outdoor AER. Significant emissions of monoterpenes, which are highly reactive with ozone (O
3) and the hydroxyl radical (OH), suggest that scented wax product use may contribute to secondary organic aerosol (SOA) formation in indoor and urban atmospheres.