Why Use Air-Sampling?
Air samples can be used to gather data about mold spores present in the interior of a house. Taking air samples during a mold inspection is important for several reasons. First of all, mold spores are not visible to the naked eye, so you need an air sample to even know whether mold spores are present. Furthermore, the types of mold present can often be determined through laboratory analysis of the air samples. An air sample analysis also provides evidence of the scope and severity of a mold problem. This analysis even helps us assess human exposure to mold spores. After remediation, new samples are typically taken to verify that all mold has been successfully removed.
In all cases, air samples are taken by using a pump that forces air through a collection device, which catches mold spores. The samples are then sent off to a laboratory to be analyzed.
When and When Not to Sample
Samples are generally best taken when 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, in the most lived-in room of the house and at the HVAC unit.
Outdoor air samples are also typically taken as a control for comparison to indoor samples. It is best to take the outdoor samples as close in time as possible to the indoor samples that they will be compared with.
Ideal Conditions for Air-Sampling
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. Common reasons to gather an air sample include: moisture intrusion, water damage, musty odors, apparent mold growth, and conditions conducive to mold growth. Samples should be taken near the center of the room, with the collection device positioned 3 to 6 feet off the ground.
Air-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.
Weather conditions can be an important factor in gathering accurate data. Severe thunderstorms or unusually high winds can affect the sampling and analysis results. High winds or rapid changes in barometric pressure increase the difference in air pressure between the interior and exterior, which can increase the variability of airborne mold-spore concentration. Large differences in air pressure between the interior and exterior can cause more airborne spores to be sucked inside, skewing the results of the sample.