Commissioning Of A Larger Naturalistic Exposure Chamber For Cat Dander

We previously developed a 2-person capacity (14.4 m3) Naturalistic Exposure Chamber (NEC) providing naturalistic and controlled exposure to cat allergen. We scaled this model to a larger 8-person capacity room (36.7 m3). Fel-d-1 was measured throughout the room and over time for 2-hour aerosolization tests. Target Fel-d-1 was 40-100 ng/m3 to mimic home environments. Robot vacuum cleaners were modified to bypass the filter and have variable suction control. Two carpets in the NEC naturally accumulated dander shed by 2 resident cats. Carpet allergen levels were monitored and supplemented by shaking cat bedding ahead of testing and by evenly distributing 10 or 20g of milled cat hair (Stallergenes, Greer). Throughout the tests, a vacuum moved about each carpet aerosolizing the aspirated dander, which was circulated by fans. Air samples (5L/min for 30-min) were collected by sampling pumps (Gilian 5000) at 4 locations across the room and 4 time-intervals. Collected Fel-d-1 was quantified by ELISA to determine air concentration in ng/m3. Repeatability was demonstrated on separate days under optimized settings (N=5). Mean Fel-d-1 (N=5) under optimized settings was 79 (±12 SD) ng/m3. Excellent temporal stability and spatial homogeneity were observed with 19% and 11% maximum deviations from the mean, respectively. The NEC method of cat allergen exposure has demonstrated superior control and repeatability of allergen levels compared to standard bedding shaking methods, while maintaining the naturalistic advantages of a field exposure-type setting. The validation of the larger NEC room presents a valuable new tool for the study of cat allergies.