In addition, this dust acts as a fertilizer for molds and bacteria to grow in your system. Dust mites thrive in this environment as well, and when they die . . . they add more fertilizer for contaminants and the next generation of dust mites! In this dirty environment, molds may begin to grow in your HVAC system.

The dangers of breathing mold of mold toxins from your HVAC system are real:

Asthma: Molds just like the kind that are found in HVAC systems can trigger asthma attacks in persons who are allergic (sensitized) to molds. The irritants produced by molds may also worsen asthma in non-allergic (non-sensitized) people.

Hypersensitivity Pneumonitis: Hypersensitivity Pneumonitis may develop following either short-term (acute) or long-term (chronic) exposure to molds. The disease resembles bacterial pneumonia and is uncommon.

Irritant Effects : Exposure to mold like the types commonly found in HVAC systems can cause irritation of the eyes, skin, nose, throat and lungs and sometimes can create a burning sensation in these areas.

Opportunistic Infections: People with weakened immune systems may be more vulnerable to infection by molds. Aspergillus Fumigatus, for example, has been known to infect the lungs of immune-compromised individuals. These individuals inhale the mold spores that start growing in their lungs. Thrichoderma has also been known to infect immune-compromised children.

Healthy individuals are usually not vulnerable to opportunistic infections from airborne mold exposure. However, molds can cause common skin infections such as Athlete's Foot and Yeast infections.

The level of some hazardous
pollutants in indoor air has been
found to be up to 70 times greater
than in outdoor air.

(U.S. Environmental
Protection Agency)