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Mold & Microbial: General Information


The following general information is from the California Department of Health Services booklet.

California Department of Health Services


 Indoor Air Quality Info Sheet


 Mold in My Home: What Do I do?

water damaged mold

This fact sheet provides information to people who have experienced water damage to their home and presents the health concerns related to mold exposure. It also provides general guidelines on mold detection, cleanup & removal of mold contaminated materials.

[editorial comment: This information from CDHS is designed for the general population of normally healthy adults. Effects of exposure to molds on the young, elderly, ill, or persons with suppressed or compromised immune systems may be significantly greater than are presented in this data sheet.]


What is it?

Molds are simple, microscopic organisms, found virtually everywhere, indoors and outdoors. Molds can be found on plants, foods, dry leaves, and other organic material. Molds are needed for breaking down dead material. Mold spores are very tiny and lightweight, and this allows them to travel through the air. Mold growths can often be seen in the form of discoloration, ranging from white to orange and from green to brown and
black. When molds are present in large quantities, they can cause allergic symptoms similar to those caused by plant pollen.

Should I be concerned about mold in my home?

Yes, if the contamination is extensive. When airborne mold spores are present in large numbers, they can cause allergic reactions, asthma episodes, infections, and other respiratory problems for people. Exposure to high spore levels can cause the development of an allergy to the mold. Mold can also cause structural damage to your home. Similarly, when wood goes through a period of wetting, then drying, it can eventually warp and cause walls to crack or become structurally weak.


What does mold need to grow?

For mold to grow, it needs:

  • food sources - such as leaves, wood, paper, or dirt

  • a source of moisture

  • a place to grow                                  

Can mold become a problem in my home?Yes, if there is moisture available to allow mold to thrive and multiply. The following are sources of indoor moisture that may cause problems:


  • flooding

  • backed-up sewers

  • leaky roofs

  • humidifiers

  • mud or ice dams

  • damp basement or crawl spaces

  • constant plumbing leaks

  • house plants - watering can generate large amounts of moisture

  • steam from cooking

  • shower/bath steam and leaks

  • wet clothes on indoor drying lines

  • clothes dryers vented indoors

  • combustion appliances (e.g. stoves) not exhausted to the outdoors.



Are all molds hazardous?

No. Most molds are relatively harmless to humans. Of the thousands of types of molds, only a relatively few have been associated with harm to humans. These include:

  • Cladosporium

  • Alternaria

  • Penicillium

  • Stachybotrys

  • Aspergillus

  • Fusarium

  • Coccidioldes



If you see moisture condensation on the windows or walls, it is also possible that you have a combustion problem in your home. It is important to have sufficient fresh air available for fuel burning appliances, such as the furnace, water heater, stove/range, clothes dryer, as well as a fireplace. A shortage of air for these appliances can result in back drafting of dangerous gases such as carbon monoxide into the home. To prevent back drafting of air, you need either open vents or a ventilation system that brings fresh air into the home to replace air that is exhausted out. Have your local utility company or a professional heating contractor inspect your fuel-burning appliances annually.

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