Mold is part of the natural environment. It is a form of fungus that is ubiquitous in character and reproduces by means of microscopic spores, which are invisible to the naked eye and drift through the air. Molds grow indoors when the spores come into contact with damp substances, whether it is wood, paper, carpets, or food. Toxic mold refers to sickness arising from exposure to certain molds.

Inhaling or touching toxic mold can cause allergic reactions in some people, as the molds produce a poisonous substance called mycotoxin. Common symptoms include headache, fatigue, and irritation in the eyes, nose, skin, and lungs. Contact with considerable quantities of toxic mold can also cause asthma attacks. Constant exposure to toxic mold is poisonous. In the 1930s, toxic mold caused the death of farm animals in Russia and other countries. Today, the agriculture industry keeps a vigil on mold in grains to prevent food supplies and animal feed from becoming infected.

Damp building equipment like drywall, wood, carpets, and carpet padding contribute to mold growth. Mold growth in an indoor environment is in general related to an indoor water or moisture problem. Leaky roofs, building maintenance problems, or plumbing issues can cause mold growth inside buildings.

Mold requires moisture to grow. Reduce indoor humidity to decrease mold growth by venting bathrooms, increasing ventilation, and using exhaust fans whenever cooking, dishwashing, and cleaning. Keep the place ventilated, and if there is an appliance that leaks or drips water, it should be fixed immediately. Repair any leaks or roofing problems within a day, as mold can grow on virtually any surface. However, cleaning up mold without taking care of the root problem, i.e. moisture, will not be of any use, as the mold will most likely come back.