Mold, Testing, and Remediation

What is Mold?

closeup of mold on wall above tile

Mold is a fungal growth that forms and spreads on various kinds of damp or decaying organic matter. There are many different mold species that come in many different colors. Molds are sometimes referred to as mildew. They are found both indoors and outdoors in all climates, during all seasons of the year. Outdoors, molds survive by using plants and decaying organic matter such as fallen leaves as a source of nutrition. Indoors, molds need moisture and a carbon source from building materials or building contents to grow.

Excess moisture is generally the cause of indoor mold growth. Molds reproduce by releasing tiny spores that float through the air until landing in other locations. When they settle on wet or moist surfaces, the spores can form new mold colonies. Moderate temperatures and available nutrient sources make most office buildings ideal for mold growth.

Exposure to molds has occurred throughout history. The types of molds found in office buildings are not rare or even unusual. It is important to understand that no indoor space is completely free from mold spores – not even a surgical operating room. Molds are everywhere, making our exposure to molds unavoidable, whether indoors or outdoors, at home or at work.

“Toxic Mold” & Stachybotrys chartarum

Certain molds are toxigenic, meaning they can produce toxins (mycotoxins). However, the molds themselves are not toxic or poisonous. Hazards presented by molds that may produce mycotoxins, such as Stachybotrys chartarum, should be considered the same as other common molds which can grow in your house or workplace. There is contradicting research on whether toxigenic mold found indoors causes rare health conditions such as bleeding in the lungs. Research is ongoing in this area.

Mold growing in buildings, whether it is Stachybotrys chartarum (Stachybotrys atra) or another mold, indicates that there is a problem with water or moisture. This is the first problem to address. For further information on Stachybotrys chartarum, go to CDC’s webpage Facts about Stachybotrys chartarum and Other Molds

rusty pipes and a water-damaged wall

Testing and Remediation of Dampness and Mold Contamination


There are no health-based standards for acceptable levels of biological agents in indoor air. We do not recommend routine air sampling for mold with building air quality evaluations. This is because mold concentrations in the air cannot be interpreted in relation to health risks.

In many cases, very short-term sampling for mold spores is performed. However, the results may not represent actual exposures. Spore counts and culture results are often included in indoor air quality reports. These do not capture the full range of exposures.

What building occupants react to is unknown. It may be:

  • Mold.
  • A compound produced by mold.
  • Something related to bacteria.
  • Compounds released into the air when wet building materials break down.

We have found thorough visual inspections and/or detection of problem areas via musty odors are more reliable. NIOSH uses these methods, which have shown association with health risks in buildings that have indoor environmental complaints.


Appropriate remediation includes:

  • Drying wetted materials within 48 hours of getting wet or remove the materials.
  • Making necessary repairs to prevent further water entry into the building.
  • Following appropriate remediation guidelines with proper containment when identifying mold on materials.

Inappropriate remediation (e.g., painting over water-damaged materials or moldy surfaces) can cause further problems with building degradation and symptoms in occupants.

For complete remediation guidelines, go to the New York City Department of Health and Hygiene’s Guidelines on Assessment and Remediation of Fungi in Indoor Environments site.