US EPA

6935107 

Journal Article 

Diurnal Variability and Emission Pattern of Decamethylcyclopentasiloxane (D5) from the Application of Personal Care Products in Two North American Cities 

Coggon, MM; Mcdonald, BC; Vlasenko, A; Veres, PR; Bernard, F; Koss, AR; Yuan, B; Gilman, JB; Peischl, J; Aikin, KC; Durant, J; Warneke, C; Li, SM; de Gouw, JA; , 

2018 

1 

Environmental Science & Technology
ISSN: 0013-936X
EISSN: 1520-5851 

52 

10 

5610-5618 

English 

29659257 

10.1021/acs.est.8b00506 

WOS:000432417400011 

https://www.proquest.com/docview/2084061563?accountid=171501&bdid=64576&_bd=pU9VPB2NR8N2%2F%2F3N%2By2jwq3BEkE%3D
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Decamethylcyclopentasiloxane (D5) is a cyclic volatile methyl siloxane (cVMS) that is widely used in consumer products and commonly observed in urban air. This study quantifies the ambient mixing ratios of D5 from ground sites in two North American cities (Boulder, CO, USA, and Toronto, ON, CA). From these data, we estimate the diurnal emission profile of D5 in Boulder, CO. Ambient mixing ratios were consistent with those measured at other urban locations; however, the diurnal pattern exhibited similarities with those of traffic-related compounds such as benzene. Mobile measurements and vehicle experiments demonstrate that emissions of D5 from personal care products are coincident in time and place with emissions of benzene from motor vehicles. During peak commuter times, the D5/benzene ratio (w/w) is in excess of 0.3, suggesting that the mass emission rate of D5 from personal care product usage is comparable to that of benzene due to traffic. The diurnal emission pattern of D5 is estimated using the measured D5/benzene ratio and inventory estimates of benzene emission rates in Boulder. The hourly D5 emission rate is observed to peak between 6:00 and 7:00 AM and subsequently follow an exponential decay with a time constant of 9.2 h. This profile could be used by models to constrain temporal emission patterns of personal care products.