10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
Abstract View
Nanoparticle Resuspension from Surfaces and Resulting Exposures Due to the Use of Consumer Nanosprays in Homes
RUIKANG HE, Jie Zhang, Gediminas Mainelis, Rutgers, The State University of New Jersey
Abstract Number: 894 Working Group: Indoor Aerosols
Abstract Nanotechnology-enabled consumer sprays are widely used as deodorizers, surface cleaners and for multiple other purposes. These nanotechnology-enabled products release relatively high concentrations of nanoparticles and their agglomerates that may become available for inhalation exposure. This study examined deposition, resuspension, and potential exposures when such nano-enabled sprays are used in a home.
Exposure scenarios examined included adults walking and young children crawling on the floor. The latter was simulated by a robotic crawler. We chose to simulate young children’s crawling because their breathing zone is closer to the floor compared to walking. Based on our earlier studies, we selected two Ag-containing and two Zn-containing spray products which generate relatively high mass concentration when applied. The products were applied in a 5 x 9 x 8 ft3 chamber with controlled background particle concentration. The experiments were performed with carpet and vinyl flooring. Each product was sprayed for 5 min, and particles were allowed to settle on the floor. The particles were resuspended by an adult walking or a robot crawling for 10 minutes every 24 h to determine if resuspension changes over time. Resuspension rate and particle size distributions were measured statically at 0.288 m and 1.1 m above the floor, as well as with a mobile instrument which measured particles in the experimenter’s breathing zone during spraying and resuspension. Filter samples were also collected to analyze the morphology and chemical composition of the resuspended particles.
The sprayed particle mass concentration ranged from 0.3 to 58.2 mg/m3 and the floor‐deposited mass density (loading) ranged from 0.00022 x 104 to 1.0 x 104 mg/m2. The resuspended particle concentration ranged from 5.2 μg/m3 to 61 μg/m3 during walking and from 3.8 μg/m3 to 9.5 μg/m3 during robot crawling, depending on the product and floor type. We found that the resuspension rate ranged from 10-1 to 10-6 h-1 and reached a peak value after 24 h for vinyl flooring and after 48 h - 96 h for carpet. As could be expected, the large particles representing agglomerates of sprayed nanoparticle contributed the most to the resuspended particle mass concentration, and small particles were the main contributors to the resuspended particle number concentration. Interestingly, the resuspension rate from the carpet was an order of magnitude higher than that from the vinyl while walking, but only 1.5x higher than that from the vinyl with the robot crawling. Also, the resuspension rate from walking was an order of magnitude higher than that from the robot crawling for both floor types. The resuspended particles and their agglomerates showed the presence of various metals, including Ag and Zn as was advertised in product composition.
Our study shows that when nanotechnology-enabled spray consumer products are used in homes, the sprayed particles not only deposit, but they can also be resuspended from flooring and become available for inhalation exposure. The extent of the resuspension depends on the flooring type, the product, as well as the activity causing the resuspension.