Comparing AirDoctor AD3500: Surprising Power for Large Rooms...Tested! We were skeptical when the AirDoctor AD3500 promised coverage for up to 1260 sq. ft., but after testing, we’re impressed. The unit’s 2x/hour circulation rate keeps our large living room fresh without overworking the motor. The UltraHEPA, Carbon, and VOC filters work seamlessly, and the Air Quality Sensor automatically adjusts settings— ours ran quietly, mostly on the lower fan setting, yet performance was consistent. Capturing particles 100x smaller than standard HEPA filters, it handles pet dander and household pollutants effectively. While we noticed no notable ozone emission, the 100% fresh air exchange rate makes it ideal for high-traffic areas. The sleek design blends into our space, and the maintenance-free pre-filter adds convenience. Overall, the AD3500 delivers surprising power for its size, making it a solid choice for larger homes.