Uploaded August 2025 | Updated September 2026, 2 weeks ago
Exposure to elevated levels of mold indoors can cause allergies, act as a respiratory irritant, trigger an asthma attack in some asthmatics, and some types of mold can even lead to infections in people with a weakened immune system. Indoor mold can also cause unpleasant odors.
Many types of mold thrive at normal to slightly elevated room temperatures. But, for mold to grow indoors, it also needs moisture, a food source, and oxygen. Moisture is the key factor influencing mold growth indoors, so controlling moisture and relative humidity in the built environment can dramatically help to prevent its growth. This is crucial as mold can begin to grow indoors in as short as 24 to 48 hours when conditions are right.
Mold does not need a lot of water to grow. For example, a little condensation can sometimes be enough. Common sites for indoor mold growth include bathrooms, basement walls, areas around windows, near leaky plumbing, and around sinks. Sources of moisture include roof leaks, condensation due to high humidity or cold spots, plumbing leaks, sanitary sewer overflows, malfunctioning humidification systems, and floods. Keep in mind, some types of water may also contain bacteria, viruses, and chemical contaminants.
Besides moisture, mold also needs nutrients, or food, to grow. Mold can grow on virtually any organic substance. Most buildings are full of these organic materials and include many building materials, furnishings, and personal belongings. While mold cannot get nutrients from inorganic materials, such as concrete, it can grow on dust or dirt on the surface.
These are just a few of the many things to know about what mold needs to grow in the built environment. To learn more about this or other indoor air quality, industrial hygiene, environmental, health, or safety issues, please visit the websites shown below.
Clark Seif Clark csceng.com
EMSL Analytical, Inc. emsl.com
LA Testing latesting.com
Zimmetry Environmental zimmetry.com
Healthy Indoors Magazine healthyindoors.com
Exposure to elevated levels of mold indoors can cause allergies, act as a respiratory irritant, trigger an asthma attack in some asthmatics, and some types of mold can even lead to infections in people with a weakened immune system. Indoor mold can also cause unpleasant odors.
Many types of mold thrive at normal to slightly elevated room temperatures. But, for mold to grow indoors, it also needs moisture, a food source, and oxygen. Moisture is the key factor influencing mold growth indoors, so controlling moisture and relative humidity in the built environment can dramatically help to prevent its growth. This is crucial as mold can begin to grow indoors in as short as 24 to 48 hours when conditions are right.
Mold does not need a lot of water to grow. For example, a little condensation can sometimes be enough. Common sites for indoor mold growth include bathrooms, basement walls, areas around windows, near leaky plumbing, and around sinks. Sources of moisture include roof leaks, condensation due to high humidity or cold spots, plumbing leaks, sanitary sewer overflows, malfunctioning humidification systems, and floods. Keep in mind, some types of water may also contain bacteria, viruses, and chemical contaminants.
Besides moisture, mold also needs nutrients, or food, to grow. Mold can grow on virtually any organic substance. Most buildings are full of these organic materials and include many building materials, furnishings, and personal belongings. While mold cannot get nutrients from inorganic materials, such as concrete, it can grow on dust or dirt on the surface.
These are just a few of the many things to know about what mold needs to grow in the built environment. To learn more about this or other indoor air quality, industrial hygiene, environmental, health, or safety issues, please visit the websites shown below.
Clark Seif Clark csceng.com
EMSL Analytical, Inc. emsl.com
LA Testing latesting.com
Zimmetry Environmental zimmetry.com
Healthy Indoors Magazine healthyindoors.com
