Air test and mold inspections
Taking air samples during a mold inspection is important for several reasons. Mold spores are not visible to the naked eye and only laboratory analysis can identify the type of mold in question. Having samples analyzed is also helpful in demonstrating the extent and severity of a mold problem, as well as in assessing human exposure to mold spores. After solving the problem, new samples are usually taken to ensure that all mold has been properly removed.
In addition, air samples can be used to collect data on mold spores inside a home. These samples are taken using a pump that forces air into a collection device in order to capture mold spores. The sample is then sent to a laboratory for analysis.
Air test: Air sampling devices
There are several types of devices used to collect air samples that can be analyzed for mold. Here are some examples :
impact samplers which use a calibrated air pump to impact the spores on a prepared microscope slide;
cassette samplers, either single use or disposable, which use forced air to impact the spores on a collection medium; and airborne particle collectors that trap spores directly on a culture dish. These can be used to identify the species of mold found.
When should we take a sample and do an air test?
It is generally best to take samples if a non-invasive visual examination reveals apparent mold growth or any conditions that may be causing it, such as moisture intrusion or water damage. Moldy odors can also be a sign that mold has spread. If no signs are apparent, one or two indoor air samples can still be taken each year to ensure good air quality at all times.
Outdoor air samples are generally used as a check for comparison with data from those inside. Two samples, one on the windward side and the other on the leeward side of the house, will help to establish a more complete picture of what is in the air and can enter the house through windows and doors. For an optimal comparison, it is strongly recommended that the indoor and outdoor samples be taken on the same day, or a few days apart at the latest.
What are the ideal conditions when collecting?
Air samples can be taken from any area of a house where mold is suspected to verify and gather more information. Intrusion of moisture, water damage, musty odors, apparent mold growth or favorable conditions for such growth are all common reasons for collecting an air sample. They must be collected near the center of the room, with the collection device placed 3 to 6 feet from the ground.
Ten minutes is enough for the air pump to run while taking samples, but this can be cut in half if you are concerned that the movement of air caused by intense indoor activity may affect the results. The sampling time can even be even shorter if there is an active source of dust, for example from a construction in progress.
Sampling must take place in habitable spaces of the house, which will be closed so that no one enters, in order to contribute to the stabilization of the air and to the reproducibility of sampling and measurements. While taking the sample, windows and exterior doors should remain closed, except during normal entry and exit from the home. It is preferable that air exchangers (other than a furnace) or fans that exchange indoor-outdoor air are turned off during sampling.
Difficulties and practical aspects of the air test
It is important to note that air sampling is just one of many tools when inspecting a home for mold problems. Indeed, an air sample is not enough to confirm or refute the existence of a problem. Such tests should be accompanied by visual inspection and other methods of data collection, such as a surface sample. The levels of spores suspended in indoor air can vary depending on several factors, which can skew the results if care is not taken to properly configure the sampling. It is highly recommended that you hire a professional indoor air sampling company to detect mold.
Air samples can be used to make sure there is not a significant source of mold not yet found somewhere in the house. In fact, they can detect long chains of spores that are still intact. Normally, these chains separate quickly as they move through the air. Thus, a sample revealing intact chains can indicate the presence of mold nearby, possibly not discovered during other tests and visual examinations.
In summary, when taken under controlled conditions and properly analyzed, air samples used to detect mold are useful for comparing the relative particle levels between a problem and a control area. They can also be crucial for comparing particle levels and air quality in an area before and after mold removal.
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