How to Test for Mold
Mold testing is an important step in the mold remediation process. It allows you to know what you are dealing with by saying conclusively if mold is present, identifying the types of molds in a given area, and even discover hidden mold growth. The two main types of mold testing are air sampling and surface sampling, but there are a variety of ways to accomplish both.
An important aspect of testing for mold is air sampling. A variety of measurement meters, spore collectors, and air pumps can be used to gather air samples. It is important to sample the air outside of the building as well as inside of it. The results between the two should show similar mold counts. The ideal place to position an air collector for mold testing is three to six feet above the ground. You should take the outdoor sample at the same height as the indoor sample.
Before turning on an air pump, you need to calibrate the flow of the pump. You can do this with the use of a rotameter. The rotameter is a user-friendly air flow meter often used by mold inspectors. It consists of a tapered glass tube with a weight inside that is raised from the pressure of the pumped air and drops from gravity. The air flow rate can be determined by the position of the float at the time of testing.
The air-flow rate through an air pump must align with the manufacturer’s instructions. It is important to follow these instructions. If the flow rate is too slow, the spores will float around the collector plate without sticking and if the flow rate is too fast, then the spores will bounce off without sticking and not give you an adequate test for mold. Samples are recorded in spores per cubic meter (spores/m3). The pump should be calibrated daily to ensure a quality reading.
Next, attach the tubing to the pump and begin sampling the air. Make sure to monitor the air flow rate during the sampling process as it should remain consistent throughout. If the air flow changes by a percentage of five or more than you must stop sampling and start over again when you can get a consistent flow. Make sure to record the start and stop time of your sampling period as well.
When the sampling is complete, your collector slide should have a thin film of particles on it. If a slide is heavily covered, that may make results impossible to read and you should take a new sample. To calculate the volume of your sample, take the number of liters pumped and multiply that by the number of minutes in the sampling period. For example if you had 15 liters of air pumping for ten minutes then you will have an equation of 15 L x 10 min. = 150L. All air samples must have the same volume for consistent mold testing readings.
You must protect your used collector slides so they are not accidentally touched or contaminated, which would then alter the results. If there is an accident, simply use a new slide and take another sample.
mVOC Canister Sampling
Microbial volatile organic compounds (mVOCs) can be a sign that mold is actively growing in the area so testing for mVOCs is a common way to track down mold. Canisters can be used to quickly gather an air sample of the contaminated area. These are then sent to a lab to determine the concentration of mVOCs inside the space and whether there is cause for concern. Testing has shown that some people have allergic reactions at just 8 ug/L of total mVOCs.