The Aller Dust Mite Controller works by emitting a range of ultrasonic sounds which although inaudible to humans, interfere with the breeding and feeding cycle of dust mites. This is effective in reducing rthe population of dust mites and associated allergens. Clinical trials show a reduction of allergy symptoms after just a few weeks use. Typical symptoms include, asthma, nasal congestion and runny nose, coughing, sneezing and eczema. The controller covers a volume of 62.8 cubic meters when plugged in. A blue light indicates the product is on and working.