There are many sources of indoor allergens known to us: pillows, mattresses, upholstered furniture, and carpets can get infested with dust mites. There are also other items and rooms in the house that can trigger allergies and asthma. Jeffrey C. May, a certified indoor air professional and author of books on indoor air quality suggests that it is very helpful to know even the unrecognized sources to be able reduce these indoor allergy and asthma triggers.
Full Article: How to Reduce Indoor Allergy and Asthma Triggers