You are absolutely right on the use of a dehumidifier to keep the humidity around 40%. I should have included that. Most molds can not grow in under 50 % humidity. Of course the ones inside us have access to our body's moisture.
There is also a problem when the humidity gets too low. You will experience more static shocks due to atmospheric low humidity or bodily dehydration. This turns your body into a microbe magnet. Static electricity attracts elements including microbes.
Somewhere I saw computer monitors as a source of aspergillus mold spores. I found it curious at the time and made a mental note. I never did further research on it. But, having experienced static problems with my body and my computer monitor at the same time when the atmosphere is very dry and creating static electricity to shock me every time I touch certain surfaces, I would say the monitor could attract mold spores floating in the air.
When you do a mold test with petrie dish of potato dextrose you open up it up for 20 minutes. Whatever lands on it during that 20 minutes grows on it. They are floating through the air