Mold spores occur in the indoor and outdoor environments. Mold spores may enter buildings from the outside through open doorways, windows, and heating, ventilation, and air conditioning systems with outdoor air intakes. Spores in the air outside also attach themselves to people making them convenient vehicles for carrying mold indoors. When mold spores drop on places where there is excessive moisture, such as pipes, walls, plant pots, or where there has been flooding, they will grow. Many building materials provide suitable nutrients that encourage mold to grow. Wet cellulose materials, including paper and paper products, cardboard, ceiling tiles, wood, and wood products, are particularly conducive for the growth of some molds. Other materials such as dust, paints, wallpaper, insulation materials, drywall, carpet, fabric, and upholstery, commonly support mold growth.
The common health concerns from molds include hay fever-like allergic symptoms. Certain individuals with chronic respiratory disease (chronic obstructive pulmonary disorder, asthma) may experience difficulty breathing. Individuals with immune suppression may be at increased risk for infection from molds. Routine measures should be taken to prevent mold growth in buildings.
In most cases mold can be removed from hard surfaces by a thorough cleaning with commercial 1 to 10 diluted bleach or a 5% hydrogen peroxide. If you have an extensive amount of mold and you do not think you can manage the cleanup on your own, you may want to contact a professional who has experience in cleaning mold in buildings. It is important to properly clean and dry the area as you can still have an allergic reaction to parts of the dead mold and mold contamination may recur if there is still a source of moisture.
Facts about Stachybotrys Chartarum and Other Molds, CDC Website