A musty odor in your microwave can serve as a surefire sign of mold growth. You may also notice the physical signs of mold, such as velvety or fuzzy patches of green or black. Under the right conditions, mold can grow almost anywhere, including the inside of a microwave.
Conditions for Growth
Mold cannot grow inside of a clean, dry microwave. Like all living organisms, mold spores require a source of food. Food particles left behind after microwaving can provide sufficient sustenance for mold, and so can layers of dirt in a microwave that has not been cleaned in some time. In addition to nutrients, mold needs moisture to grow. If moisture is collecting in a dirty microwave, it can develop a mold problem.
Not the Ideal Environment
Even in a dirty microwave, mold will have a very difficult time growing under most circumstances. First of all, mold spores cannot germinate instantaneously, meaning that moisture must linger for a prolonged time to allow for sufficient growth. Since microwaves function as enclosed spaces, they do not collect humidity or water damage as easily as other household surfaces. Still, if you allow water to settle at the bottom of your microwave, it may remain present long enough to allow for mold growth. For example, if you microwave a cup of noodles filled with water, some of the boiling water may spill over and remain inside the microwave. For this reason, you should always dry out your microwave if excess moisture collects.
Mold and Microwave Radiation
Microwave radiation does not effectively kill mold spores. While extreme heat from a microwave can neutralize some active colonies, you should not rely on microwave heat to kill mold. Proper mold elimination requires you to disinfect the microwave and remove the spores completely. Even if you neutralize an active colony, the mold spores may regenerate and create new colonies at a later time. You can spray the inside of your microwave with white vinegar, and thoroughly scrub the interior with a damp cloth. Rinse the microwave with water and dry it completely.
If you have mold growing inside of your microwave, do not microwave food until you have thoroughly cleaned and disinfected the inside. Once again, microwaving does not effectively kill mold, and if you allow mold spores to collect on the food you eat, you may become ill, suffer respiratory symptoms or allergic reactions.