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7 Statements from the CDC about Mold Exposure

The CDC has a webpage entitled Basic Facts about Mold and Dampness. This brief page provides information about managing a damp building and mold growth, along with potential health risks caused by indoor air pollution. In this article, I provide commentary on seven statements.

For reference, the CDC page is set up in a question-and-answer format. In some cases, where I felt it would be essential for context, I included the prompt question. Also, for the purposes of brevity, I have included only excerpts of some of the statements. I encourage anyone interested to study the CDC webpage (5 minute read).

“Mold growing in homes and buildings indicates that there is a problem with water or moisture. This is the first problem to address.”

Moisture begets mold, along with other hazardous microbial growth. Sources of excess moisture may include roof leaks, uncontrolled humidity, and condensation within air conditioning ductwork. Eliminating this moisture is the first priority according to the CDC—even before removing the mold itself. If mold is removed before the moisture source is eliminated, then any ongoing dampness will simply drive more mold to grow on the building.

“How do you know if you have a mold problem?”  “Large mold infestations can usually be seen or smelled.”

The CDC standard for establishing the presence of a mold problem is based upon visible mold and musty odors. What is remarkable about this statement is the standard that the CDC set for establishing a “mold problem” does not necessarily depend upon commercial mold testing, such as air sampling. Yet in the medical legal arena, overt visual evidence of mold—in the form of pictures and videos—and reports of moldy smells are often treated as inconclusive evidence.

In its position paper, the American Industrial Hygiene Society supports this assertion, noting that “health assessment is primarily based on the nature and extent of the mold and water/moisture damage and the type of reservoirs present” and that “semi-quantitative estimates of the extent of visible mold/dampness has been identified as being the best predictor of long and short-term health outcomes.”

“If you can see or smell mold, a health risk may be present. You do not need to know the type of mold growing in your home, and CDC does not recommend or perform routine sampling for molds. No matter what type of mold is present, you should remove it.”

Mold, along with other microbial growth, should be removed. The CDC minimizes the value of routine sampling, reasoning that the mold needs to be removed regardless of the type anyway. According to the American Industrial Hygiene Association, this dismissal of routine sampling may leave out key information: “Investigation and remediation of mold and moisture damage in buildings must be based on an informed inspection augmented by the judicious use of existing sampling methods, primarily for the purpose of detecting any hidden damage.

“Since the effect of mold on people can vary greatly, either because of the amount or type of mold, you cannot rely on sampling and culturing to know your health risk.”

The effect of mold on people does indeed vary greatly. In some households, only one member of the family might be substantially affected by the damp conditions. But that’s often the case in medicine. Not everyone who smokes a pack a day gets lung cancer. Not everyone exposed to asbestos develops mesothelioma. The risk of an adverse health outcome from a chronic respiratory exposure, including of indoor biological pollutants, is variable and influenced by factors such as genetics and immune sensitivity.

“A link between other adverse health effects, such as acute idiopathic pulmonary hemmorhage among infants, memory loss, or lethargy, and molds, including the mold Stacybotrys chartarum has not been proven. Further studies are needed to find out what causes acute idiopathic hemorrhage and other adverse health effects.”

Here the CDC is denying certain significant health links. Consider acute idiopathic pulmonary hemmorhage among infants, a devastating condition that involves lung bleeding. A geographic cluster of cases occurred in Cleveland, Ohio in the 1990s in infants under one year of age. Researchers found that the infants who developed this condition were more likely to live in homes where Stachybotryswas present. (Etzel)

The counterargument is association is not necessarily causation—just because the infants with the bleeding lungs lived in the moldier homes doesn’t mean that the high levels of Stachybotrys (or other molds) is to blame. But researchers determined that the same health effects also occurred in infant mice who were exposed to mycotoxins produced by Stachybotrys. (Yike) As the researchers somberly reported: “All dead pups had extensively hemorrhagic lungs.”

Point is: The CDC recognizes only a small subset of the full range of symptoms and injuries caused by indoor air pollution.

The CDC’s dismissal of common symptoms of memory loss and malaise is at odds with the preponderance of clinical and scientific evidence of the mold-injured. I will cover this oversight in another article in fuller detail, but will leave you with the position of the World Health Organization’s on the neurological effects of mold exposure: “Such health effects as fatigue, headache and difficulties in concentration indicate that microbes or other agents present in damp buildings have neurological effects.”

“Are there any circumstances where people should vacate a home or other building because of mold?” These decisions have to be made individually. If you believe you are ill because of exposure to mold in a building, you should consult your physician to determine the appropriate action to take.

The CDC defers to the physician for determining environmental health risk. CDC places clinical judgement at the center of the decision-making process about the decision to vacate a unit—not the opinion of a landlord or the result of a commercial mold test.

“Standards for judging what is an acceptable, tolerable or normal quantity of mold have not been established. Sampling for mold can be expensive, and standards for judging what is and what is not an acceptable quantity of mold have not been set.”

As with the World Health Organization, the CDC can’t reasonably establish a safe level for mold exposure. Commercial testing, such as air sampling, does not provide a definitive indication of health risk because of its methodological limitations and because it depends on heath factors of the occupant. An elevated level of indoor air pollution that produces minimal symptoms in one occupant may cause disabling injury in another—since injury from mold-exposure is not necessarily a dose-dependent effect, a safe level of exposure cannot be absolutely defined for the general population.


Etzel RA, Montaña E, Sorenson WG, Kullman GJ, Allan TM, Dearborn DG. Acute Pulmonary Hemorrhage in Infants Associated With Exposure to Stachybotrys atra and Other Fungi. Arch Pediatr Adolesc Med. 1998;152(8):757–762. doi:10.1001/archpedi.152.8.757

Heseltine, Elisabeth, and Jerome Rosen, eds. “WHO guidelines for indoor air quality: dampness and mould.” (2009).

Yike, Iwona, et al. “Infant animal model of pulmonary mycotoxicosis induced by Stachybotrys chartarum.” Mycopathologia 154 (2002): 139-152.