Dust Mites are found in humid conditions. They just love the beds we sleep in! The dust mite was discovered 25 years ago. Since then, it has become increasingly apparent that dust mites play a major role in the cause of allergies such as asthma.

Common allergy symptoms such as sneezing, runny nose, coughing and asthma attacks are often attributed to colds. When an allergic reaction is suggested, reference is often made to dust. However, it is not the dust itself, but the dust mites, and their excreta that is the usual culprit.

Additional illnesses associated with the house dust mite include: conjunctivitis and eczema; tightness in the chest at night; sneezing and itchiness during vacuuming and bed-making; and blocked/runny nose (rhinitis) becoming worse at night.

Up to 1000 dust mites can be living in a single gram of dust. Each dust mite excretes an average of 20 pellets of excreta every day. In a gram of dust there could be 250,000 pellets of excreta. The pellets are very dry and rupture easily to release large numbers of sub-pellets, which can remain airborne for days. These pellets are so small and light that they are easily made airborne by our turning in our sleep, or walking on a carpet.

The dung pellets released by a dust mite have been found to contain a protease enzyme, known as Der P1 from the digestive system. This has been found to be highly allergenic, non biodegradable (remains active for years) and water-soluble.
Normally, a particle the size of a dust mite excreta pellet, would be dealt with by usual lung functions and expelled by transport in the mucus. Der P1 however, is water-soluble and, consisting mainly of salt water and a little protein, is taken up by the mucus. Once dissolved, the Der P1 rapidly digests the protein and causes localised irritation and swelling to the bronchiole wall in a person sensitive to the allergen. This allergic reaction occurs in minutes and, in isolation, can be gone in an hour (Acute reaction). Exposure to high concentrations of pellets night after night, will cause chronic reaction, which takes months to form. The sufferer is now asthmatic. Chronically swollen and restricted airways will then react to exhaust fumes, pollen, sudden blasts of air or even emotional factors, to trigger an asthmatic attack whereby muscles go into spasm and the asthmatic sufferer has difficulty breathing.

Studies have suggested that up to 10% of a two-year-old pillow can be made up of dust mites and their droppings.
The average length of the creature is 0.3mm and they belong to the genus Dermatophagoides, which is translated to 'skin eater', this appropriate name is given due to the fact that they feed on animals. One of their main meals is dead human skin, which has a high protein content. The dust mite is also related to spiders and ticks, therefore is part of the Arachnid family.

These microscopic insects prefer living in humid conditions where they can absorb water from the air and the environment. Ideal conditions in terms of food consumption and development of these mites are at relative humidity's of 70-80%, and when the temperatures are 20-25°C.

These ideal conditions are found in the one place where we probably spend more time than any where else, in our bed! The average person sleeps 8 hours a day and within this period would have been sleeping with anything up to 2 million dust mites.

The transformation from an egg to a full adult mite is under a month and therefore there could be a new generation of dust mites every 3-4 weeks. A female mite can lay between 25 to 50 eggs within 3 weeks and 40 to 80 within a period of 6 weeks. The actual lifespan of a dust mite is about 10 weeks.
The conditions in which we live in today's society makes perfect breeding grounds for dust mites.

Pre- 1950/60's the air in an average house changed 7.5 times a day, by natural means. Since the introduction of central heating, double-glazing, insulation and the fact we are more security conscious, the daily air-change in a house can be as little as 1.5 times a day. Hence causing a modern “greenhouse” living environment.