Environmental Medicine

Molds in the Environment

What is Mold?

A mold is a microscopic fungus that grows and lives on plant or animal matter or on non-organic objects. Most molds are made up of filaments and reproduce through the production of spores, which spread by air, water, or insects.

There are many thousands of species of fungi. Common indoor molds include:

Alternaria
Aspergillus
Cladosporium
Mucor
Penicillium

Molds are found everywhere in the environment, both indoors and outdoors, and throughout the year.

Reactions to Mold

Molds cause allergic symptoms in many people. Common reactions to molds include:

Nasal stuffiness
Eye irritation
Wheezing when breathing

More severe reactions may occur among workers, such as farmers, who are exposed to large amounts of molds in occupational settings, including fever or shortness of breath. Mold infections may occur in the lungs of persons with obstructive lung disease.

How to Decrease Mold Exposure

When outside, avoid areas that are likely to have mold, such as:

Compost piles
Cut grass
Wooded areas
Damp, mossy areas
Greenhouses
Antique shops

When inside, try to:

Keep humidity levels below 40 percent
Ventilate showers and cooking areas with exhaust fans
Use an air conditioner or a dehumidifier during humid months
Do not use carpet in susceptible areas such as bathrooms or basements
Dispose of, or thoroughly dry and clean, objects that accidentally become wet such as carpets or upholstery

This page was last updated on: December 17, 2009.

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