Deciding if mold is present in sufficient quantities to cause property or health problems involves first gathering information about past and present moisture issues, as well as evidence of obvious mold growth (like visible mold colonies and/or odors). Chronic elevated moisture or humidity will eventually result in mold growth and greatly increases the likelihood that mold is already present, even if it can’t yet be seen.

Regardless of the initial findings, it may be desirable to take samples in order to determine the types and concentrations of mold present. Pre-treatment sampling, when combined with post-treatment sampling, is also useful in confirming the effectiveness of treatment.


There are many ways to collect and analyze samples. Each type of collection and each type of analysis tells you a little bit of the story. No individual sampling technique will give you the whole story. Remediators who understand this should only suggest the sampling that is needed to understand enough of the story to successfully correct your problem.

If sampling is recommended, it should only be performed by a Certified Mold Inspector. This individual is trained in sampling techniques and analysis report interpretation. Sampling should be conducted according to standards and protocols required by the Certifying Entity and the Independent Laboratory performing the analysis.

Testing is usually done to compare the levels and types of mold spores found inside the building with those found outside of the building, or for comparison with another location in the building. In addition, air sampling may provide tangible evidence supporting a hypothesis that investigators have formulated. For example, air sampling may show a higher concentration of the same species of mold when the HVAC is operating than when it has been turned off. This finding may convince the Investigator that the mold is growing within, and being disseminated by, the HVAC system. Conversely, negative results may persuade the Investigator to abandon this hypothesis and to consider other sources of mold growth or dissemination.

If you know you have a mold problem, it is more important to spend time and resources removing the mold and solving the moisture problem that causes the moldy conditions, than to undertake extensive testing for the type and quantity of mold.

If you are in doubt about sampling, consult with G&C Environmental to help you decide if sampling for mold is necessary or useful.