No wonder you're looking at this title twice. Mold on concrete is something you probably don't expect to see. But there it is, on a concrete floor, wall, patio or walkway. Concrete itself does not promote the growth of fungi; it crops up when moisture from a leaking pipe, humidity or condensation interacts with organic material on the concrete, such as carpet padding, drywall or paper. So put first things first: Clean up the area and then fix the water problem so the mold doesn't return. The steps to prevent mold are straightforward -- you won't have to look twice.

Step 1

Get into high gear if you see a water leak or pool of water. Clean up and dry the area immediately and thoroughly to prevent further mold growth.

Step 2

Inspect your home's water sources and channels to see if they're contributing to mold growth. Focus on your downspouts and your air conditioner's drain lines. If you're perplexed about where a puddle of water or condensation is coming from, call a licensed home inspector to help pinpoint the problem.

Step 3

Keep indoor humidity levels below 60 percent – even better, between 30 percent and 50 percent. You can measure relative humidity with a humidity meter, a nifty instrument available at most home improvement stores. While you're at it, check appliances that produce moisture – such as your dryer and stove – to ensure that they're vented properly.

Step 4

Encourage air flow by opening doors and windows when possible. Use floor or table fans to help keep the concrete dry.

Step 5

Installing a whole-house dehumidifier or portable dehumidifier might be the final step for stubborn moisture problems indoors. Consult a licensed heating, ventilation and air conditioning technician to ensure that you purchase the correct size for the area you are trying to treat.