Indoor air pollutants have increased over the past few decades for variety of reasons. Contributing to indoor air quality issues in homes are construction of more tightly sealed buildings, reduced ventilation rates to save energy, the use of synthetic building materials and furnishings, and increased use of chemical products such as pesticides, housekeeping supplies, and personal care products. The four basic factors affecting indoor air quality (IAQ) are indoor air pollutant sources; the heating, ventilation, and air-conditioning (HVAC) system; pollutant pathways; and occupants.
Moisture and Biologicals:
Moisture problems in homes can result in the growth or amplification of biological and microbial organisms like mold, mildew, dust mites and pet dander. Exposure to these organisms can increase the risk of allergic illness, trigger asthma, cause respiratory infections, or have other health effects. Common sources of moisture include high indoor humidity, plumbing leaks, and water leaks. Poorly maintained heating, ventilation and air-conditioning systems can also contribute to moisture problems. To remedy the problem, the source of excess moisture must be found and fixed, and contaminated materials must be removed and discarded if they cannot be thoroughly cleaned.