Natural Born Mold Killers

A reader asks The Green Guide:

After a really rainy spring, I've had serious problems with mold inside my house. Is there an easy way to get rid of it without having to revert to chlorine-based cleaners?

The Green Guide responds:

Serious mold problems require professional expertise to correct, and for good reason: Mold can be dangerous to your health and damaging to your home. Molds actually release volatile organic compounds, called microbial VOCs or MVOCs, that can cause headaches, nasal irritation and even mood changes. A few indications that your mold problem might require professional help include mold that returns despite repeated efforts to clean it, mold that has a strong smell or is black-green in color (which indicates Stachybotrys atra, one of the most health-damaging strains of black mold), and mold that has lingered after a unique yet large moisture event, such as flooding.

If your problem is manageable enough to tackle yourself, it's important to determine the point of origin. Mold won't grow without moisture, so make sure to remove all sources of water, for instance a leaky pipe inside your wall or a crack in the foundation into which water might seep, and "food" on which it might grow, such as surrounding papers and fabrics.

For smaller problems, having some tried-and-true and environmentally safe ingredients that kill mold is invaluable. Here are the best of these:

1. Australian tea tree essential oil (also known as melaleuca) is a broad-spectrum fungicide that is often used medicinally. It has a very strong smell that is too strong for some people, and if this is the case, move on to other suggestions, below. Tea tree oil is expensive, but a little bit goes a long way.

To make a mold-killing spray, place 1 teaspoon of tea tree oil in a spray bottle with 2 cups of water. Shake to blend. Spray on moldy areas and don't rinse. The smell will dissipate in a couple of days.

2. Vinegar is a mainstay of traditional cleaners and effective against mold. Use the 5 percent white distilled solution so as not to stain fabric, and use it "straight up": just add it directly into a spray bottle. Don't rinse. Vinegar is the cheapest available method of killing mold, besides direct sunlight.

The trick with these three sprays is not to rinse so the ingredients have time to do their work, but in a few days, clean up the dead mold with some soap and water.

3. Borax will also reduce some mold spores and is useful for scrubbing walls, including cement walls found in basements. Cover such areas with a mixture of 1 cup borax to 1 quart of hot water (to dissolve the borax), and let dry without rinsing. Vacuum and dust off the borax a few days later.

If you're tempted to combine borax with vinegar to get more bang for your buck, hold off. Borax and vinegar neutralize each other, so you won't get the same cleaning power as if you used the ingredients individually.

For more homemade cleaner recipes, see "DIY Household Cleaners".