What is Air Sampling for Mold in a Home?

South End Plumbing, Heating, & Air Expert Tips

What is Air Sampling for Mold in a Home

Air sampling in a home or building can be part of a mold inspection. If you’re thinking you may have mold, it could be difficult or not impossible to tell visually. Mold spores aren’t visible to the eye. For many types of mold, an air sample, then a lab, is needed to get an accurate reading. Getting a sample scientifically analyzed lets owners and technicians know about the type, level, and remediation plan for mold in a structure. An air sampling can even be important medically if someone is suffering from ill symptoms or a condition due to mold. Once mold has been removed, an air sampling might be needed to know the mold isn’t reoccurring.

How Does it Work?

Doing an air sampling in an interior area is a pretty simple procedure. Air samples are taken by a pump. The sample goes to a lab where everything in the air, including mold spores, can be analyzed.

There are different devices used for air samplings, each with a little different purpose and method. Some examples of these methods are:

  • Airborne particles – These collection devices gather spores onto a culture dish. This is efficient for identifying the species of mold – often it’s more than one if there’s a mold problem – in a sample.
  • Cassette – This is typically a one-time or disposable sampling device. It is an air pump that takes in an air sample.
  • Impaction – This is a calibrated air pump that takes in air and spores, putting them onto a slide which is then used in a microscope.

When Should There Be an Air Sample?

Air sampling for mold is usually a good idea after an initial, visual inspection for mold. If an expert finds mold or conditions where mold is likely, then it’s likely smart to go to an air sampling. Mold is likely where there’s water damage, too much moisture, or dark and musty areas in, or under, a home or building.

If an initial exam doesn’t find mold, but there could be mold, with there being an odor or possible conditions, then an air sample can be done. You can have a sample done in a home, for example, in a high-traffic area of the home. A sample can also be done in a space in an HVAC system. This will give a reading about the air quality and airflow in a property.

Air samples from outside the home, but in the same immediate area, should be gathered. This is done as a control sample compared to the indoor sample. Having indoor and outdoor samples gives more information about the air entering a home, for example through the HVAC system. Some conditions may be mold. Some air quality factors may not be mold, but due to the climate and environment contributing to the air in the home or building. Even if doors and windows aren’t open often, the local air quality may be a big factor in a home’s air.

Where to Sample

Air samples can be collected from any area in, or outside of, a house. Any room or space which is likely to have mold growth should be tested. Rooms or spaces with bad odors, water damage, frequent moisture, or other signs of mold growth can have samples taken. A sample should be taken from the center of a room, in the open, with the sampling device about 3-6 feet high.

For many types of mold, an air sample, then a lab, is needed to get an accurate reading.How Long to Sample

An air test should take 5-10 minutes. A pump or device should run for about 10 minutes for a usual test. The sample time may be cut down for some reasons. If there’s a great deal of air movement, the sample time may be shortened so samples aren’t altered by too much airflow. Another example is in an area with a great deal of dust, such as from a construction site. In this case, a sampling might collect too much dust so it should be shortened.

Testing should be carried out in a room with closed conditions so airflow is as calm and stable as possible. Windows and doors should be kept closed. Fans and HVAC units are usually off during an air sampling collection.

Weather conditions can be an important consideration for collecting exact mold samples. Severe thunderstorms or high winds can influence the sampling. High winds or quick rises or falls in barometric pressure may change air pressure from inside to outside. This may enhance the irregularity of airborne mold spores. Big differences in air pressure from an interior space to outside it can cause more airborne spores to be gathered in a test, skewing the outcomes of the test.

Problems With Air Sampling

Air sampling is a useful part of finding, then eliminating, a mold problem. It is just one part of a tool kit, though. It should be only part of an overall inspection and process. Visual inspections, other methods, and doing a surface sample are other parts of a thorough inspection.

Interior airborne mold spore levels can vary according to numerous factors, and this can cause skewed results if care is not exercised to set up the sampling correctly. Also, because only spores are collected with an air sample and a sample may actually be damaged during collection, recognition of the mold and mildew type can be harder than with a sample gathered by tape or a cultured sample.

Air samples are good to use as a screening tool for finding, or ruling out, a large or hidden mold growth which hadn’t been detected yet in a structure. This is because an air sample test can detect long chains of spores that are still undamaged. These chains usually break apart rapidly as they travel with the air, so a sample that exposes intact chains can indicate there is mold nearby, and possibly not found during other tests or assessments.


In summary, when taken correctly and properly analyzed, air samplings for mold are effective in testing interior air. They can be quite important for finding mold levels and testing air quality in an area before and after mold remediation.


At South End Heating and Air, we are Charlotte’s affordable AC experts. Call us anytime for a free consult and free estimate. We’ll evaluate your system and help make recommendations for optimum value. After all, we want to keep you cool all summer long and warm in the winter. Just schedule a visit with one of our technicians to talk about how we can help. Would you like to learn more options our techs can help you with? Give us a call 704-684-5339.

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