We have only recently begun to understand the health hazards of fungal exposure. I hope to provide enough information here so that you may identify and correct the problem.

There are over 100,000 types of molds in the world. In Canada alone there are over 270 indoor varieties.
Some molds produce secondary metabolites that produce toxins called mycotoxins which are very dangerous to your health. We usually are unaware we are breathing mold spores and mycotoxins until we develop health problems ... some as severe as chronic bronchitis, heart problems, cancer, multiple sclerosis and much more.

I'm not trying to educate anyone as to which mold is toxic and which is not. I'm not a mold expert. The fact remains that regardless of the toxicity of mold in your home your health may be at risk. Unfortunately we are not effectively being protected by any level of our government or by the building codes used to set guidelines and regulations for building our homes. We are basically left in the dark to deal with this all on our own.

Moisture left within any structure will allow mold to grow and live there indefinitely. The spores grow and may become airborne and circulate within your home. Common areas for mold to grow are basements, showers, behind and under bathtubs, under sinks and in the drywall where plumbing is located. If there's moisture in any material for over 24 hours at a time can cause mold to develop. Keep things dry and you will most likely never have a problem.

Mold can be killed using bleach but if mold has contaminated absorbent materials such as carpet, drywall, or insulation, that material may have to be completely removed. All remaining areas need to be dry and free of any moisture before repairs are conducted to damaged areas. Also if you are tearing things apart to get at the mold you'll need to protect yourself and the rest of your home from the airborne spores caused by your disturbance, so masks, gloves, barriers and ventilation is important.