Mold is a microscopic plant that is part of the fungi family naturally existing in nature. Visible mold is the result of colonization of the fungi,  for example 1 million mold spores in 1 square inch.  Visible mold growth may not become a risk to human health unless touched or eaten.   Since most people would not knowingling eat mold,   the greater risk is that when visible mold growth or invisible,  very aerodynamic mold spores & fungal fragments are disturbed and released into the breathing pathways of humans.   Humans are exposed to mold every day at home, at work, or outside.  Mold becomes an indoor health issue when humans are over exposed to mold spores and fragments.  Mold has two main effects on humans

1  Toxic

Toxic reactions are rare and are usually found in people who have compromised immune systems. Toxic reactions are usually associated with the species and less dependent on exposure levels.

2  Allergic

Allergic reactions are the most common and affects more than half the population.  Allergic reactions are mostly associated with exposure levels rather than the toxic nature.

MIS-UNDERSTANDING #1

Killing mold eliminates risk to mold exposure.  WRONG

Killing mold spores will reduce the potential number of viable colony forming spores

Dead spores & fungal growth can still cause toxic & allergic reactions.  Depending on the species the best way to reduce or eliminate the health risks is by complete removal or reduction to background levels

MIS-UNDERSTANDING #2

Removing visible mold growth eliminates risk to mold exposure.  WRONG

Once again removing mold growth reduces the potential number of viable colony forming spores,  displaced settled spores before removal or during poor removal procedures will result increased concentrations of spores and fungal fragments in the air

Mold grows on any surface when the right conbination of conditions occur which are, presence of mold spores,  organic material( even dust on impervious materials), water activity and temperature.