Well, that was easy enough. The answer is no, I don’t appear to have any problem with airborne mold in my house.
Briefly:
Recall from Post #1895, I decided to buy ten Petri dishes pre-filled with growing medium, to do a simple test for airborne mold in my house. As discussed in that post, Petri dishes with growing medium provide a crude test for mold. Open up the sterile dish, expose it for an hour, and count the number of mold colonies that form over the next two days. More than four, on any one plate, and that’s cause for concern and further testing.
It’s not great, it’s not foolproof, it’s not very quantitative. But if there’s a lot of mold spores floating around my house, something will end up growing on these plates.
I could have bought various forms of “mold test kits”, but as far as I could tell, all the cheap ones boiled down to Petri dishes, plus the option to have a lab “read” the results. It seemed cheaper and faster just to buy a few sterile Petri dishes filled with growth medium, and count the resulting mold colonies myself.
My only hesitation was based on many of the pictures I saw, of moldy Petri dished (“plates”). Seems like whenever household mold is discussed, people seem obliged to show Petri dishes swarming with mold. That made it look like it was going to be hard to count the number of distinct mold colonies that formed.
Turns out, that’s not true. Or, at least, not true unless you’ve got one heck of a mold problem. If you don’t have a problem, counting the colonies is easy.
So here are pictures of my “plates”, that is, Petri dishes with agar-gel growth medium, exposed to the air for one hour, then incubated for two days. In total, out of six plates, two of them had a single easily-identified mold colony, each.
My point is that reading these was trivial. Beyond just looking at them with the tops of the Petri dishes removed, I held them up to the light and looked through, and so on. But it’s just as simple as it looks above. Shine a light on them and have a look.
Two dishes (from the same part of the house) had a single, obvious mold colony each. The other four were completely mold-free.
Bottom line: For $30 (for 10 sterile Petri dishes with gel growth medium), and maybe ten minutes’ time, I think I have pretty well ruled out the presence of a significant airborne mold problem in my home.
