1. Dehumidifiers. Dehumidifiers are a great tool for preventing mold growth. Mold grows when there is a water source, which could be a leak, a flood, or high humidity. Dehumidifiers do a great job of keeping the relative humidity in your home at a low enough level (below 50% is best) to deter mold growth. Be sure to have good ventilation in your home (and closets) for the dehumidifier to work best. You can also purchase an inexpensive hygrometer, an instrument used to measure relative humidity, at most hardware stores.
2. HEPA Air Purifiers. HEPA air purifiers often claim to trap 99% of dust, mold spores and pollen in the air. I have found this to be true, in my experience. These devices do a good job of filtering the air you breathe in your home, which can be invaluable to people with allergies. Drawbacks: a bit pricey (usually over $100) and they usually only cover the area of one or two rooms. If you decide to purchase one, make sure it has a HEPA filter. Only HEPA filters can trap mold spores.
3. HEPA Vacuums. There are some pretty fancy vacuums out there these days, and the expensive ones usually offer HEPA filtration. This means that they filter out the smallest dust, dander, mold spores, etc that are in your carpet, instead of just kicking them up into the air when they clean the bigger dirt particles. Like HEPA air purifiers, I find HEPA vacuums to work well. (If you are purchasing a vacuum and want to trap mold spores, make sure it has a HEPA filter for the same reasons you need a HEPA filter for your air purifier as described above.). In fact, I recommend anything using HEPA media when it comes to improving indoor air quality.
4. MoldTough Drywall. This is a relatively new drywall product out there that advertises itself as mold resistant. While it is definitely more mold resistant than plain drywall, it still doesn’t prevent water from getting behind the drywall and soaking the insulation and 2x4s, causing mold growth. I recommend using this product in kitchens and bathrooms, where you know there will be an extra amount of water present, but not throughout the whole house.

The first three products can definitely help those of us with allergies. But if you don’t suffer from severe allergies, none of these products are really necessary if you keep your house clean and dry, with lots of ventilation and fresh air exchange. Dormant mold spores are everywhere in our environment – in the air we breathe and the carpet we walk on. These dormant spores are just waiting for a damp food source to germinate on. But if you ventilate your home well, stop leaks right away, and dry out flooding right away, you shouldn’t ever have to worry about a mold problem in your home.