Dust mites—sometimes called bed mites—are the most common cause of allergy from house dust. Dust mites live and multiply easily in warm, humid places. They prefer temperatures at or above 70 degrees Fahrenheit with humidity of 75 to 80 percent. They die when the humidity falls below 50 percent. They are not usually found in dry climates.
Dust mite particles are often found in pillows, mattresses, carpeting and upholstered furniture. They float into the air when anyone vacuums, walks on a carpet or disturbs bedding and they settle once the disturbance is over.
A house does not need to be visibly dirty to trigger a dust mite allergy reaction. The particles are too tiny to be seen and often cannot be removed using normal cleaning procedures. In fact, a vigorous cleaning can make an allergic person’s symptoms worse.