Professional Home Mold Testing

Professional home mold testing, exactly what does that mean? Allow me to back up for a second and explore what home mold testing is. You can purchase a home mold test kit at one of your local home improvement centers or on the internet. What you get is a sealed package that contains a petri dish with an agar (nutrient source) usually MEA (malt extract agar). You open the package, take out the petri dish and remove the lid and place it on a horizontal surface and wait. Mold spores in the air will land on the food (nutrient) source and start to grow. There are some pro’s and con’s to consider here. You look at your little science experiment and start to panic as you see this plethora of mold growing.


First thing you need to realize is that there are mold spores floating in the air all the time. Put down a piece of wet drywall and see how long it takes for mold to start colonizing provided you keep it moist. So, visually this home mold test kit is alarming, but it’s not yielding any useful data. You now have to send it away to a lab and pay an analysis fee, (that’s in the fine print). Now, if the lab finds certain indicator species that require a very high moisture content on the plate then you can use that information to assume you may have a mold problem. Consumer Reports did research on these mold test kits and sent them in for analysis. They found that when they sent in some plates that hadn’t even been opened the report indicated there was mold, yet the dish was never opened, so it was packaged with mold. Other samples that they submitted after exposing the plates to known mold came back with reports of no mold detected. Bottom line is, they’re not accurate.

Now, let’s talk about professional home mold testing. An experienced, knowledgeable environment consultant would first perform a comprehensive assessment of the property, but that’s another blog article on mold inspection for another day. There are many mold sampling protocol’s you can follow, but most companies are only familiar with one or two.  If we want to compare the home mold test kit with what a professional would do, then we would talk about sampling under a sterile, controlled environment. You need to start with an Andersen impactor that has an exact number of precision drilled holes designed to allow mold spores and little else to impact onto the petri dish. This impactor has to be connected to a precisely calibrated sampling pump. This mold sampling strategy can yield useful data, but it has it’s limitations (or cons). Only culturable mold spores will grow out. Culturable, being what the lay person would define as alive versus non-culturable, what would be defined as dead. Non-culturable (dormant) spores would go undetected with this type of sampling.

This is part of a continuing educational series on mold testing and sampling protocols. Please stay tuned.

Craig Camel

Advanced Mold Diagnostics