Environmental Public Health Division

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FAQ’s About Mold

The Harris County Public Health and Environmental Services (PHES) has summarized this fact sheet to address some of the most common questions and concerns regarding mold.

This document is not a legal mandate and should be used as a guideline. Currently there are no United States Federal, Texas State, or Harris County regulations for evaluating potential health effects of fungal contamination and remediation. These guidelines are subject to change as more information regarding fungal contaminants becomes available.

 What is mold and where is it found?

Molds (fungi) are present everywhere – indoors and outdoors. They serve an important, positive role, by helping to break down organic matter. There are more than 100,000 species of mold. At least 1,000 species of molds are common in the U.S. Some of the most common molds found are species of Aspergillus, Penicillium, and Cladosporium. Most often molds are confined to areas near a source of water. Removing the source of moisture – such as through repairs or dehumidification –is critical to preventing mold growth.

How can mold affect my health?

The most common types of mold are generally not hazardous to healthy individuals. However, people who have asthma, hay fever, or other allergies or have weakened immune systems are more likely to react to mold. The most common symptoms are running nose, eye irritation, cough, congestion, and aggravation of asthma. A small percentage of the population can develop more serious effects – such as fevers and breathing difficulties – but these effects are uncommon. Some types of mold can cause more serious health problems, but this is much more rare.

The presence of fungi on building materials as identified by a visual assessment or by bulk/surface sampling results does not necessitate that people will be exposed or exhibit health effects. In order for humans to be exposed indoors, fungal spores, fragments, or metabolites must be released into the air and inhaled, physically contacted (dermal exposure), or ingested. Whether or not symptoms develop in people exposed to fungi depends on the nature of the fungal material (e.g., allergenic, toxic, or infectious), the amount of exposure, and the susceptibility of exposed persons. Susceptibility varies with the genetic predisposition (e.g., allergic reactions do not always occur in all individuals), age, state of health, and concurrent exposures. For these reasons, and because measurements of exposure are not standardized and biological markers of exposure to fungi are largely unknown, it is not possible to determine "safe" or "unsafe" levels of exposure for people in general.

What about the toxic mold?

Some studies have suggested an association between Stachybotrys and pulmonary hemorrhage/hemosiderosis in infants, generally those less than six months old. Pulmonary hemosiderosis is an uncommon condition that results from bleeding in the lungs. The cause of this condition is unknown, but may result from a combination of environmental contaminants and conditions (e.g., smoking, fungal contaminants and other bioaerosols, and water-damaged homes), and currently its association with Stachybotrys is unproven.

This fungus or mold Stachybotrys, grows only on wood or papers that have gotten very wet for more than a few days or so. (It does NOT grow on plastic, vinyl, concrete products, or ceramic tiles). If the wood/paper gets wet and is not cleaned up and dried, the fungus may grow and spread. The fungus is black and slimy when wet. It is NOT found in the green mold on bread or the black mold on the shower tiles (but the shower tiles should be kept clean too). If you have had plumbing leaks, roof leaks, flooding, or sewer backup in the past year, look for mold or a musty odor. . Note: not all black mold is Stachybotrys , but moldy homes are not healthy homes.

How can you be exposed to mold?

When moldy material becomes damaged or disturbed, spores (reproductive bodies similar to seeds) can be released into the air. Exposure can occur if people inhale the spores or directly handle mold-containing material and accidentally ingest it. Some molds can produce chemicals called mycotoxins. Mycotoxins may cause illness in persons who are sensitive to them (for example, persons who are prone to allergies) or when persons are exposed to large amounts in the air (typically associated with certain occupations).

What should I do if I see mold in my home? Should I have it tested?

Mold should be cleaned as soon as it appears. Although any visible mold can be tested by an environmental consultant and/ or analyzed by a laboratory specializing in microbiology, these tests can be very expensive – from hundreds to thousands of dollars. There is no simple and cheap way to sample the air in your home to find out what types of mold are present and if they are airborne. Even if you had your home tested, it is difficult to say at what levels molds would cause health effects. Therefore, it is more important to get rid of the mold rather than find out more about it. The most effective way to treat mold is to correct underlying water damage and clean the affected area. How should mold be cleaned? . Persons cleaning mold should be free of symptoms and allergies. A person should also consider wearing gloves and a dust mask during cleaning. Use a common household bleach and water mix (1 part bleach to 10 parts water) to clean it. You can add a little dish soap to the bleach and water mix to cut any dirt and oil on the wall that can hold mold. Do not add ammonia to the bleach solution! This can result in dangerous vapors . Scrub the surface with a detergent and then apply the bleach solution and allow it to air dry. If the mold returns quickly or spreads, it may indicate an underlying problem such as a leak. Any underlying water problems must be fixed to successfully eliminate mold problems. If mold contamination is extensive, a professional abatement company may need to be consulted. Will your health or your child’s health be affected and should you see a physician? If you believe that you or your children have symptoms that you suspect are caused by exposure to mold, you should see a physician. Keep in mind that many symptoms associated with mold exposure may also be caused by many other illnesses. You should tell your physician about the symptoms and about when, how, and for how long you think you or your children were exposed. 

This document is in the public domain. An individual or organization without permission may reproduce it.  

Additional Resources

• http://www.epa.gov/iaq/molds
• http://www.cal-iaq.org/cal-iaq%20moldinformation.htm