ACS reagent formalin (37% formaldehyde) was utilized. Porcine muscle was used for the electrosurgical substrate. Testing was performed in a 50 m 3 simulated operating room. The room was equipped with typical OR air flow obstructions including surgical lights, tables and medical equipment. A diagram of the experimental design and images of the OR and equipment used are shown in Figure . The OR is exposed to formalin (37% formaldehyde in water). Formaldehyde evaporates and mixes into the OR air. When the air cleaning device contains catalyst (upper left), formaldehyde mixed into the OR air is reduced via catalytic conversion to H2O and CO2. When catalyst is not present, the formaldehyde concentration is not significantly changed.