Mold and Biological Contamination

Maintaining a healthy indoor environment is important in workplaces, buildings, and homes. Biological contaminants in workplaces include; bacteria, molds, mildew, fungi, viruses, dust mites, pollen, spores, insect frass, and rodent dander. In homes, pets contribute to indoor contaminants with their dander and other biological excretions.


Maintaining a healthy environment includes minimizing the amount of biological contamination. These "bioaerosols" are extremely small living organisms or fragments of living things suspended in the air. Most commonly these bioaerosols and their sources are:


  • Pollens originating from plants

  • Viruses transmitted by people and animals

  • Bacteria carried by people, animals, soil, and plant debris

  • Bacteria and fungus growing in air conditioning equipment, humidifier reservoirs, dehumidifier drip pans, toilets, ice machines, showerheads, traps, water-damaged building materials, and crawl spaces

  • Dust mites (one of the most powerful biological allergens) living in carpets, bedding, and upholstered furniture

  • Animal dander and excretions (saliva, urine, feces) introduced by household pets


All of these aerosols can be easily transported and circulated by building or home ventilation systems. Additionally, ductwork and air handling systems can easily become breeding grounds and distribution pathways for bacteria, mold, fungi, mildew, and other biological contaminants.




Mold and mildew originate from spores, which exist in the air around you. Under the right conditions, spores settle and form colonies. The right conditions are moisture, warmth, and a source of nutrition (such as wood or paper). The classic example is cardboard boxes, books, or wood stored in a damp basement.


Eliminating moisture sources and reducing humidity are the primary methods to control mold. Water-damaged materials, wet surfaces, or standing water serve as breeding grounds for molds, mildews, bacteria, and insects. In the event of flooding or water intrusion, quick drying or disposal of all “food source” materials is important.


Mold Prevention and Small Scale Cleanup 

  • Identify and correct moisture problems or water leaks.

  • Store materials in sealed moisture-resistant containers (sealed plastic storage containers).

  • Elevate all storage and containers to keep from direct contact with concrete floors.

  • Maintain relative humidity below 50%.

  • Clean small areas (a few square feet) by scrubbing non-porous surfaces with either detergent and water or dilute 10% bleach/ 90% water solution.

  • Dispose of porous mold-contaminated materials, such as carpet, drywall, or wood.

  • Routinely inspect heating and cooling system duct work for dirt, signs of mold/mildew, loose insulation, leaks, and signs of condensation.

  • Change air filters on a regular basis (quarterly or as indicated by system manufacturer).

  • If you continue to have mold problems, consult an indoor air quality professional for indoor air quality testing and remediation.



Contact Eagle to discuss your assessment and remediation needs. ​​​