Most people spend little to no time in their garages, however if it is attached to your home, it is essentially part of your home.
Mold that develops within the garage may float into your home as a mold spore each and every time you open the door.
Let's face it your garage door, many times a 16 foot wide wall of your home opens several times a day allowing a huge amount of outside air to enter. This exchange of air can be humid air in or cold air in to a warmer area generating moisture that is then trapped in the garage.
Not to mention but does anyone have a garage door that seals properly with no gaps?
You don't have to spend much time in your garage looking around to become keenly aware of the hundreds of potential areas mold may be growing as you read this information.