Air Sampling for Mold

Taking air samples during a mold inspection can be important for several reasons.  Mold spores are not visible , and the types of mold present can often be determined through laboratory analysis of the air samples.  Having samples analyzed can also help provide evidence of the scope and severity of a mold problem, as well as aid in assessing human exposure to mold spores.  After remediation, new samples are typically taken to help ensure that all mold has been successfully removed.

When and When Not to Sample

Samples are generally best taken if visual, non-invasive examination reveals apparent mold growth or conditions that could lead to growth, such as moisture intrusion or water damage.  Musty odors can also be a sign of mold growth.  If no sign of mold or potential for mold is apparent, one or two indoor air samples can still be taken, at the discretion of the inspector and client.

Outdoor air samples are always taken as a control for comparison to indoor samples.  Two samples — one from the windward side and one from the leeward side of the house — will help provide a more complete picture of what is in the air that may be entering the house through windows and doors at times when they are open.

Taking samples is always advisable if a resident of the house is under a physician’s care for mold exposure, if there is litigation in progress related to mold on the premises.

Where to Sample and Ideal Conditions

In any areas of a house suspected or confirmed to have mold growth, air samples can be taken to help verify and gather more information.  Moisture intrusion, water damage, musty odors, apparent mold growth, or conditions conducive to mold growth are all common reasons to gather an air sample. .

Sampling should take place in livable spaces within the house under closed conditions in order to help stabilize the air and allow for reproducibility of the sampling and measurement.  While the sample is being collected, windows and exterior doors should be kept shut other than for normal entry and exit from the home.

Difficulties and Practicality of Air Sampling

It is helpful to think of air sampling as just one tool in the tool belt when inspecting a house for mold problems.  An air sample alone is not enough to confirm or refute the existence of a problem, and such testing needs to be accompanied by visual inspection and other methods of data collection, such as a surface sample.  Indoor airborne spore levels can vary according to several factors, and this can lead to skewed results if care is not taken to set up the sampling correctly.  Also, since only spores are collected with an air sample and may actually be damaged during collection, identification of the mold type can be more difficult than with a sample collected with tape or a cultured sample.

Air samples are good for use as a background screen to ensure that there isn’t a large source of mold not yet found somewhere in a home.  This is because they can detect long chains of spores that are still intact.