People do not typically see dust mites as they are extremely tiny with an average size of around 0.011 inches. However, hundreds and thousands of these creatures can be found in every home. They feed on the dead cells released from the topmost layer of the skin of people and house pets. These creatures are not parasites as they do not affect the human body through direct contact. However, they can trigger allergies and make asthma symptoms worse. That is why each and every homeowner must take effort to reduce their number as much as possible. In order for you to take the right action, you must be well familiar with the life cycle of dust mites. You have to know that it is perfectly possible for viruses to accumulate in your air vent. The more serious problem is that they can easily spread to the rest of the house via the heating, ventilation and air conditioning system and affect the people and any pets inside. You feel that dust is everywhere around your house. No matter how hard and how frequently you clean it, it keeps building up on surfaces. The issue may be due to dust accumulation in the air vents. When considerable dust deposits are present in the heating, ventilation and air conditioning system, the fine particles are simply circulated around the house and cannot be removed with regular house cleaning. The HVAC system uses a set of filters which capture dust particles and fine debris. These generally do a good job, but their efficiency is reduced with time. As the filters get filled with dust and dirt, their capacity falls down. As a result, a good amount of the particles get deposited inside the air vents.