Mold Questions

Do I Have a Mold or Moisture Problem?

You have a mold or moisture problem if you see discolored patches (could be dark or many other colors) or cottony or speckled growth on walls or furniture, or evidence of water-damaged surfaces, or if you smell an earthy or musty odor.  You also may suspect mold growth or a moisture problem if people have upper or lower respiratory symptoms when in the house, classroom, or workplace (see the health effects of mold).

If you see mold or current water damage in your building, you should look for the source of moisture.  You may find mold growth underneath water-damaged surfaces (for example, wallpaper or carpet) or behind furniture, walls, floors, or ceilings.

How Do I Know if Mold Is Affecting My Family's Health?

Basically, if you see indoor water damage, dampness, or mold, or smell mold, the chances are higher that people in the building will have or may develop respiratory health problems.  So whether or not you know of a respiratory health problem associated with being in the building, you should identify and eliminate excess moisture sources, and cleanup and remove water-damaged materials and mold.  This will help prevent future problems, especially for infants and children.  Both allergic and non-allergic people can become sick from dampness and mold.  The best time to solve a health problem is before it happens.


Should I Test for Mold, or Have a Professional Test for Mold?

It is not necessary to know how many mold spores or what type of mold is present to determine if a mold problem needs to be fixed.  If you observe visible mold growth or water-damaged surfaces, or smell moldy or musty odors, there is an underlying moisture problem that must be first identified and fixed.  All moldy materials must also be removed or, if they are not porous, they can be cleaned.  Removing or cleaning mold without fixing the underlying moisture problem is not enough to protect health.


What Should I Do if I Have a Mold or Moisture Problem?

Identify the location in your building with evident dampness or mold.  If the source of the problem is visible, eliminate the source of moisture and clean mold from moldy surfaces.  If the mold is on porous materials such as carpet or upholstered furniture, you may need to discard and replace them.

You may need professional help if you cannot find the source of mold or moisture or if you cannot fix the problem.  It can be difficult in some cases to identify the source or design an effective solution.  Mold may be growing behind wallpaper, above ceiling tiles, under carpets, or inside the ventilation system.  Moisture meters may help you to identify hidden moisture inside walls, ceilings, and building surfaces.

How Do Professionals Test for Mold?

The US EPA and the CDC do not recommend testing for mold to decide if there is a dampness or mold problem that needs to be fixed.  The presence of dampness, water damage, or mold, or of moldy odors is all the evidence you need to know that the dampness or mold problem needs to be fixed.  Results of sampling for mold are not scientifically interpretable yet for making decisions about health effects.


Are There Biological Tests for Mold?

No blood, urine, or other clinical tests have been documented as valid methods to determine if a person has been exposed to mold or mold toxin, the amount of mold to which someone was exposed, or if mold has made him/her ill.  Skin-prick and blood tests can identify if a person is hypersensitive (allergic) to mold; however, molds also have health effects that are not allergic, so such a test may not be very informative.

Click here to read more about airborne allergens including mold spores.
Click here to read the CDPH statement on the misinterpretation of stachybotrys serology (black mold).
Click here to read the CDC statement on the state of the science on molds and human health.

When I Clean Up Mold, Do I Need Protection, or Should I Hire a Professional?

A homeowner or building maintenance personnel generally can handle small mold problems—total area less than 10 square feet—by using personal protective equipment.  Large contamination problems—areas greater than 100 square feet—may require an experienced, professional contractor.  However, the size criteria are based on professional judgment and practicality because we have limited information in this area.  Solving moisture problems may require professional help.

Click here to read the "NIOSH Interim Guidance on Personal Protective Equipment and Clothing for Flood Response Workers."  This document includes advice that under some work conditions, NIOSH-approved respirators may be necessary if there is a chance for exposure to mold-contaminated materials or environments.

Is There Guidance on Hiring a Contractor to Fix Mold or Moisture Problems?

A good place to start is the AIHA "Guidelines for Selecting an Indoor Air Quality Consultant," the North Carolina "Hiring a Mold Consultant or Contractor," or the California "Guidance for Hiring IAQ Consultants."

Some companies specialize in water damage restoration and can advise on cleaning homes after a flood (for example, the Association of Specialists in Cleaning and Restoration (ASCR) and the Institute of Inspection, Cleaning, and Restoration Certification (IICRC)).


logo cdph1 California Indoor Air Quality is a program of the California Department of Public Health. It is our mission to investigate indoor air pollution, develop solutions, and promote healthy indoor environments. Read more about our work.

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