system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Is fungi in the air everywhere? How does mold just on appear out of nowhere on something that sits in your house if there's moisture? How does mold and fungi work?
gpt
Mold spores are ubiquitous - they are pretty much everywhere.  Normal indoor spore count ranges from 500 to 5,000 spores per cubic meter, and outdoor spore counts can be as much as 50,000 spores per cubic meter in summer and fall in many areas.  Moldy buildings can have much higher spore counts, sometimes as high as 500,000 spores per cubic meter.  Since they're nearly everywhere, all it takes is the right environment for spores to sprout and become mold - just some water and organic material (like paper or wood or drywall).