AAAR 37th Annual Conference October 14 - October 18, 2019 Oregon Convention Center Portland, Oregon, USA
Abstract View
Dynamics of Ozone Reactivity for Different Indoor Surfaces Driven by Diurnal Ozone Exposure
MICHAEL WADE, Atila Novoselac, Richard Corsi, The University of Texas at Austin
Abstract Number: 679 Working Group: The Air We Breathe: Indoor Aerosol Sources and Chemistry
Abstract Ozone reactions with indoor surfaces lead to the secondary emission of oxidized products to the indoor space. These reactions can also lead to long-term degradation of indoor materials, ranging from cultural artifacts to common indoor surfaces such as latex paint. Indoor ozone has even been reported to change the morphology of lead-based paints, increasing exposure of building occupants to lead. Previous research indicates that the reactivity of some new indoor materials with ozone decreases with exposure to realistic ozone concentrations and then regenerates during periods absent of ozone. While ozone removal to a wide range of indoor materials has been studied, the vast majority of past studies have been “one-off” (short-term) experiments that utilize new materials. In our chamber study, we tested the dynamics of ozone reactivity - driven by diurnal ozone exposure cycles of 6 hour exposure and 18 hour no exposure - for four common indoor materials: latex painted gypsum board, clay based paint, particle board, and ceiling tile. Eight samples of each material were tested for deposition velocity in experiments that simulated a five day long ozone exposure with diurnal cycles of ozone concentration. The results show that the deposition velocity varies significantly depending on material (average values ranging from 1 to 3 m/h), with the lowest value for particle board and the highest value for ceiling tile. The results also show that on a daily bases ozone reactivity is decreasing (up to 20%) for all materials. However, overnight (when surfaces are not exposed to ozone) the reactivity recovers to near the initial value from the previous day. As the surfaces were not exposed to any air overnight (no ozone exposure), the study suggests that changes in the chemical composition of material surfaces occurs during ozone cycling, perhaps due to chemical diffusion within material itself to the surface, or dynamic partitioning of lower vapor pressure reaction products between material surfaces and overlying air.