Molds are microscopic organisms that live on plant or animal matter. Present virtually everywhere, they can be found growing on organic material such as soil, foods, and plant matter. In order to reproduce, molds produce spores, which spread through air or water.
These spores act like seeds and can form new mold growth if the conditions are right. When mold spores land on a damp spot indoors, they may begin growing. There are molds that can grow on wood, paper, carpet, and foods.
Exposure to mold can cause health effects in some people. The most common effects are allergic responses from breathing mold spores. These allergic responses include hay fever or asthma and irritation of the eyes, nose, throat or lungs.
We usually cannot say how much mold is too much as our reactions to allergens can vary greatly depending on individual sensitivity. Allergic responses can come from exposure to dead as well as to living mold spores. Therefore, killing mold with bleach and or other disinfectants may not prevent allergic responses.
Less common effects of mold exposure include infections and toxic effects. Serious infections from living molds are relatively rare and occur mainly in people with severely suppressed immune systems. Many types of molds may produce toxins but only under certain growth conditions. Toxic effects have been reported from eating moldy grain, but evidence is weak that breathing mold spores in buildings causes toxic effects.
When excessive moisture or water accumulates indoors, mold growth inside the home will often occur, particularly if the moisture problem remains undiscovered or un-addressed. The best way to control indoor mold growth is to control moisture.
Controlling Moisture in Your Home
Water in your home can come from many sources. Water can enter your home by seeping through basement floors or from leaks in the roof or windows. Showers, or even cooking, can add moisture to the air in your home.
The amount of moisture that the air in your home can hold depends on the temperature of the air. As the temperature goes down, the air is able to hold less moisture. This is why, in cold weather, moisture condenses on cold surfaces (e.g. drops of water on the inside of a window). This moisture can encourage mold to grow.
Ways to control moisture in your home:
- Fix leaks and seepage. If water is entering the house from the outside, your options range from simple landscaping to extensive excavating and waterproofing. The ground surface surrounding the house should slope away from the house. Water in the basement can result from the lack of gutters, or from water flow towards the house. Water leaks from pipes or around tubs and sinks can provide a place for mold to grow.
- Use exhaust fans in bathrooms and kitchens to remove moisture (as well as odors and grease) from the home.
- Keep heating, ventilation, and air-conditioning (HVAC) drip pans clean, flowing properly, and unobstructed.
- Vent moisture-generating appliances, such as dryers, to the outdoors.
- Maintain low indoor humidity, below 60% relative humidity, ideally 30-50%.
- Watch for condensation and wet spots. Clean and dry wet or damp spots within 48 hours. Repair sources of moisture problems.