Really? Why? What concentration? Really? Yes. Why? No toxic fumes. Concentration? Three percent is fine. Put it in a spray bottle, spray, let set for 10 minutes, scrub, then wipe clean. HELLO, One reason is that bleach cannot totally murder mold developing in permeable materials. The chlorine in bleach cannot enter into porous surfaces for example, drywall or wood. The chlorine is left on the surface of porous materials and only the water component of the bleach is absorbed into the material, giving more moisture for the mold to feed on. A portion of the mold at first surface may be killed however the roots of the mold are left in place importance the mold before long returns, abandoning you in a cycle of rehashed dying. Maybe this is the reason a few individuals accept that spraying bleach on mold doesn't affect it however rather just bleaches its shading so you can no more see it. Another weakness of bleach is that it can harm the materials it's utilized on as it is an unforgiving, corrosive chemical. Chlorine bleach also gives off harsh fumes and it even produces toxic gas when mixed with ammonia. There are more secure options, for example, borax or vinegar which don't create risk fumes or leave behind toxic residue. Thanks