One of the questions I hear most in regards to cleaning up mold in the household is: "Should I just use some bleach on it?".
Here's an emphatic answer for you: No!
Household bleach is generally a solution containing 4-6% sodium hypochlorite and 0.01-0.05% sodium hydroxide. It is most frequently used as a disinfectant or a bleaching agent in our clothing. US Government regulations allow food processing equipment and surfaces to be sanitized with solutions containing bleach, provided that the solution is allowed to drain adequately before contact with food, and that the solutions do not exceed 200 ppm. If higher concentrations are used, the surface must be rinsed with potable water after sanitizing. A 1 in 5 dilution of household bleach with water (1 part bleach to 4 parts water) is also effective against many bacteria and some viruses, and is often the disinfectant of choice in cleaning surfaces in hospitals.
However, as a fungicide (or "mold killer") on porous surfaces such as walls, floors, ceilings, and cabinets, it is not effective – in fact, it can actually provide nutrients to the mold and make problems worse. The Clorox ® Company, OSHA, and the US EPA all have determined that bleach should not be used in mold remediation. While bleach appears to kill mold, just the surface mold is affected – the hidden mold underneath the surface remains alive and well.
Bleach can also be extremely dangerous, and in the shadow of the 'green' movement, is not environmentally friendly. Mixing bleach with other cleaning solutions or detergents that contain ammonia can produce highly toxic fumes including cyanide gas. A small percentage of the sodium hypochlorite will also break down into chloroform and carbon tetrachloride. It was estimated in 1992 using market data, that stored household products would have contributed to 12 tons of chloroform and 28 tons of carbon tetrachloride. Chloroform breaks down in the troposphere and it was estimated that about 96,000 tons of carbon tetrachloride are released annually.
So what do you use? The object of mold removal is to clean the surface and remove loose moldy material, not to try to sterilize the surface. Certain mold-contaminated materials that cannot be suitably cleaned (drywall, carpeting, and curtains) should simply be discarded. Clothing and bedding linens or towels can be washed or dry-cleaned. For hard, non-porous surfaces, any cleaning method that removes surface mold is fine: warm water and soap are your best choice. Stains that are left behind, such as on framing lumber, are generally harmless, provided that you keep the areas properly dry. If you don't keep the area dry, new mold growth will readily occur on many surfaces regardless of the old stains that were left from the prior mold cleanup.
Remember to always hire a professional when you are unsure, are dealing with a large area, or if anyone in the home is experiencing symptoms. Simply killing mold is not always the answer. Dead airborne mold material can be as equally bothersome as living mold!