There are tens of thousands of mold spores in the air at all times, but that’s just one reason why mold is so difficult to control

Not all mold is bad. Molds produce the antibiotic penicillin, the immunosuppressive drug cyclosporine, and much of the world’s supply of citric acid. And that’s to say nothing of cheese.
But some molds, like black mold, release harmful mycotoxins or trigger allergies or asthma. The problem is that all molds – good or bad – are really difficult to control.
For one, molds produce tens of thousands of spores, which are invisible to the naked eye. They’re around you all the time. In some cities, mold counts have been as high as 125,000 spores per cubic meter.
Plus, molds have incredibly broad diets. They love your bread and cheese, but they’ll also eat paper in your walls – and even soap.