In order to test the propensity of the air recirculating device to remove formaldehyde from the air of an OR when interfaced with a transition metal oxide catalyst, we pre-polluted a simulated OR with formaldehyde by placing six open dishes of formalin (37% formaldehyde in H2O) in the center of the room with the ventilation turned off. The air recirculating device was turned on during this process in order to help the formaldehyde mix more uniformly throughout the room. The build-up of formaldehyde concentration in the OR is shown in Figure . The first section of the graph shows the background condition of the room for approximately 30 min, which essentially shows no increase in formaldehyde levels. Upon exposing the room to formalin, a steady build-up in formaldehyde concentration occurs, as expected. The formalin containers were removed after approximately 1 hour of exposure in which the formaldehyde concentration increased by approximately 4 ppm. As noted above, the air cleaning device was left on during this process and after. Note that the device contains neither activated carbon nor catalyst during this initial build-up stage. Once the formalin solutions were removed from the room, the concentration gradually decreased as shown in the third section of the graph in Figure . The reduction in formaldehyde during this phase is attributed to natural diffusion out of the room and possibly other processes including adsorption onto surfaces or absorption into materials. After approximately 1 hour, an activated carbon filter was inserted into the device. Section 4 of the graph shows that the rate of formaldehyde removal does not change when activated carbon is interfaced with the air recirculating device. While activated carbon has been shown to effectively remove toluene under similar conditions when placed in this same air cleaning device, formaldehyde is more challenging. After monitoring formaldehyde levels for 1 hour with activated carbon inserted into the device, an open cell polyurethane foam containing transition metal oxide catalyst was inserted. Section 5 of Figure shows that upon incorporation of the catalyst, the rate of formaldehyde removal dramatically increases. After 1 hour the formaldehyde concentration decreases by 2.12 ppm, which corresponds to a 72% reduction in the amount of elevated formaldehyde. The rapid decay was modeled with a biexponential fitting, indicating at least two types of processes occurring. Time constants, T1 and T2, were extracted from the fitting and differ in an order of magnitude, indicating a fast and slow process. The values are 30.2 ±0.2 and 133 ±4 minutes, respectively. Equation 1