The Association of Home Appliance Manufacturers (AHAM) certifies and verifies the air purity claims of manufacturers. Particle size, percentage of particles removed, and volume of air moving through the purifier are all used to determine the air purifier’s CADR. The higher the CADR, the better and more effective the air purifier. A good baseline is that the CADR should be twice the fan speed’s power. If an air purifier uses 50 watts at the highest speed, it should have a CADR of 100.