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Put on protective gear first. Check the HVAC system for contamination. Recognize when a professional service is needed.
Wear old clothing and long gloves that extend to the middle of your forearms. Put on an N-95 respirator, and follow the instructions that came with it to ensure a proper fit. Wear goggles without ventilation holes.  You can purchase an N-95 respirator mask online or from a hardware store for about $12 to $25. Inspecting for mold can stir up airborne spores, so it’s important to wear protective gear. Look for mold near the intake of your heating/ventilation/air conditioning system. Inspect inside the air ducts for a musty smell or noticeable mold growth. If all you find is dust in the return registers, that’s normal and you can vacuum or remove the registers to clean them.  If you don’t find any signs of mold, and no one in your household has unexplained illness, symptoms or allergies, your air ducts are most likely not contaminated. If you suspect contamination in your HVAC system, turn it off and don’t run it until you have the air ducts cleaned. Contact a professional mold removal service if you find a strong odor, damage from contaminated water, and/or areas of mold larger than ten square feet (three meters), approximately three feet by three feet (91 cm by 91 cm). Read online reviews or obtain a referral for a qualified mold remediation contractor. Check their references and ask what EPA recommendations or other professional guidelines they’ll follow.  For large areas of mold, the basement and HVAC may need to be sealed off with plastic sheeting.  Contaminated water can occur from flooding or sewage backup. A strong, moldy odor may indicate unseen mold growth behind walls, under flooring or beneath baseboards. You may be able to obtain a free estimate detailing what services are needed. The average cost for mold remediation is about $7,500.