65 Mold Statistics: The Alarming Truth About Mold

Mold is not just an unsightly nuisance in your home – it's also a serious health hazard. The effects of mold exposure can range from mild allergic reactions to serious respiratory problems and even long-term neurological damage.

Published On

October 1, 2023

Mold is not just an unsightly nuisance in your home – it's also a serious health hazard. The effects of mold exposure can range from mild allergic reactions to serious respiratory problems and even long-term neurological damage. Unfortunately, many people underestimate the dangers of mold and fail to address the issue promptly. That's why it's crucial to educate yourself about mold and take action as soon as you suspect a problem.

To emphasize the importance of addressing mold, here are 27 shocking mold statistics that highlight the serious health risks associated with this common household problem:

Top 10 Key Mold Statistics

  1. Approximately 70% of homes have some kind of mold in them.
  2. People with asthma, allergies, or other breathing conditions may be more sensitive to mold.
  3. At least 45 million buildings in the United States have unhealthy levels of mold.
  4. Keeping humidity levels under 50% will prevent mold growth.
  5. 93% off chronic sinus infections have been attributed to mold. (Mayo Clinic, 1999)
  6. In the U.S., it's estimated that allergic rhinitis related to mold and dampness costs about $3.7 billion.
  7. The most toxic form of mold is black mold.
  8. If a building is found to have indoor air quality (IAQ) issues, there is a 30% chance that it will be remodeled.
  9. Canadian experts found 270 different mold species in different buildings.
  10. Mold forms within48 hours after there is water damage.

Health Problems of Mold

  • Respiratory Issues: Exposure to mold can cause a variety of respiratory issues, including coughing, wheezing, and shortness of breath. In fact, one study found that individuals who lived in mold-infested homes were 40% more likely to develop asthma (Source: Institute of Medicine).
  • Infections: Mold can cause infections in the lungs, skin, and other organs. According to the Centers for Disease Control and Prevention (CDC), some types of mold can even cause serious systemic infections in people with weakened immune systems.
  • Allergic Reactions: Mold spores are a common allergen that can trigger allergic reactions ranging from mild symptoms such as sneezing and runny nose to severe reactions like anaphylaxis. It is estimated that up to 30% of the U.S. population may be allergic to mold (Source: American College of Occupational and Environmental Medicine).
  • Neurological Problems: Studies have linked mold exposure to neurological problems such as headaches, memory loss, confusion, and mood changes (Source: National Institute of Environmental Health Sciences).
  • Skin Irritation: Exposure to mold can cause skin irritation or rashes in some individuals.
  • Eye Irritation: Prolonged exposure to mold spores can cause eye irritation such as redness, itchiness or watery eyes.
  • Fungal Toxicosis: Fungal toxicosis occurs when mycotoxins produced by molds enter the body through ingestion or inhalation causing symptoms like fatigue, headaches, joint pain etc (Source: American Academy of Allergy Asthma & Immunology).

Mold and Air Pollution

  • Indoor air can be up to 10 times more polluted than outdoor air, largely due to mold and other pollutants.
  • Mold spores are present in the air we breathe both inside and outside, with concentrations varying depending on location and weather conditions.
  • The World Health Organization (WHO) estimates that indoor air pollution causes 4.3 million deaths per year worldwide.
  • In the United States, poor indoor air quality is responsible for an estimated 21% of asthma cases and 25 million missed work or school days each year.
  • According to a study by the Environmental Protection Agency (EPA), children who live in homes with high levels of mold are at a higher risk of developing respiratory problems such as wheezing and coughing.
  • A study by Harvard University found that exposure to high levels of indoor air pollution can lead to cognitive decline among older adults.
  • The American Lung Association estimates that poor indoor air quality costs Americans over $150 billion each year in medical expenses and lost productivity.

Household with Molds Statistics

  • The most common place for mold to grow in homes is the bathroom, with 70% of bathrooms containing some form of mold.
  • Mold can also be found in kitchens, with 68% of kitchens having some mold growth.
  • Basements are another common area for mold growth, with over 60% of basements having mold present.
  • Attics can also harbor mold, with around 40% of attics containing some form of mold growth.
  • Bedrooms can have mold issues as well, with approximately 35% of bedrooms having some level of mold present.
  • Mold can also grow on clothing and household fabrics, with up to 20% of households reporting issues with moldy clothes or linens.
  • Homes that have experienced water damage are at a significantly higher risk for developing mold problems, with up to a 50-100% increased likelihood compared to homes without water damage.

Buildings with Molds Statistics

  • Schools: According to a study by the Government Accountability Office, 50% of schools in the United States have problems with indoor air quality, which can lead to mold growth.
  • Hospitals: A survey conducted by the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) found that 12% of hospitals had indoor air quality issues related to mold.
  • Offices: The National Institute for Occupational Safety and Health (NIOSH) estimates that up to 30% of office buildings have significant mold growth.
  • Apartments: A study published in the Journal of Environmental Health found that nearly half of surveyed apartments had some form of mold growth.
  • Hotels: An investigation by ABC News found that many hotels across the United States have serious mold issues, including high-end luxury hotels.
  • Retail Stores: Mold growth is a common problem in retail stores, particularly those located in humid climates. According to a report by FacilitiesNet, mold is one of the most common indoor air quality issues faced by retailers.
  • Sports Facilities: Indoor sports facilities such as gyms and arenas are at high risk for mold growth due to high humidity levels. In fact, a study published in the Journal of Athletic Training found that over 40% of surveyed sports facilities had visible mold growth.

Slime Mold Statistics

  • There are over 900 known species of slime molds.
  • Slime molds can grow to be several feet long and wide.
  • The largest recorded slime mold covered over 2,200 square feet in Oregon's Malheur National Forest.
  • Slime molds are not actually fungi, but rather a type of amoeba that forms colonies under certain conditions.
  • Some species of slime mold are bioluminescent, meaning they emit light in the dark.
  • Slime molds have been found to be capable of solving complex problems and making intelligent decisions without a brain or nervous system.
  • In Japan, some types of slime mold are considered a delicacy and are used in traditional cuisine such as soups and salads.

Food Mold Facts

  • Bread mold is the most common type of food mold. It can be found in most households and is responsible for a large percentage of food spoilage. (Source: USDA)
  • Moldy food can cause serious health problems. Some types of mold produce mycotoxins, which can lead to liver damage, kidney failure, and even cancer in severe cases. (Source: World Health Organization)
  • Cheese is one of the most common foods affected by mold growth. While some types of cheese are intentionally made with mold, such as blue cheese and Roquefort, other cheeses can become contaminated with harmful molds during the production process or storage. (Source: FDA)
  • Fruits and vegetables are also prone to mold growth. Berries, tomatoes, grapes, and citrus fruits are particularly susceptible to mold due to their high moisture content. (Source: University of Wisconsin-Madison)
  • Mold growth on nuts and grains is a major concern for food manufacturers. Moldy nuts and grains can not only spoil the taste and texture of the product but also release mycotoxins that pose a serious health risk to consumers. (Source: International Association for Food Protection)
  • Food preservation methods can help prevent mold growth. Refrigeration, freezing, drying, and salting are all effective ways to inhibit mold growth and extend the shelf life of perishable foods. (Source: USDA)
  • The global market for anti-mold agents was valued at $1.8 billion in 2020 and is projected to reach $2.5 billion by 2027, driven by increasing demand from the food industry for safe and effective ways to prevent mold growth in packaged foods. (Source: ResearchAndMarkets.com)

Impacts and Losses Due to Mold

  • Property Damage: Mold can cause significant damage to property, including walls, ceilings, carpets, and furniture. In fact, the cost of mold-related property damage in the United States is estimated to be around $3 billion per year (Source: Insurance Information Institute).
  • Decreased Property Value: Homes and buildings with a history of mold problems can experience a decrease in value by up to 30% (Source: National Association of Home Builders).
  • Lost Productivity: Exposure to mold can lead to decreased productivity in the workplace due to respiratory issues, allergies, and other health problems. It is estimated that poor indoor air quality costs employers over $15 billion per year in lost productivity (Source: EPA).
  • Increased Healthcare Costs: Individuals who develop health problems due to mold exposure may face increased healthcare costs for doctor visits, medications, and other treatments. The average medical cost for a family affected by mold is around $6,000 per year (Source: Mold Advisor).
  • Legal Liability: Property owners who fail to address mold problems may be held liable for damages resulting from exposure to toxic molds. In fact, there have been numerous lawsuits filed against landlords and property managers for failing to disclose or remediate mold problems.
  • Business Interruption: If a business is forced to shut down due to a severe mold infestation, it can result in significant financial losses due to lost revenue and unplanned expenses associated with remediation efforts.
  • Negative Publicity: Businesses or organizations that are found to have serious mold problems can suffer negative publicity and damage their reputation among customers or clients.

The Prevalence of Mold

  • According to a study by the Centers for Disease Control and Prevention (CDC), about 50% of homes in the United States have mold.
  • Mold is more common in humid regions, such as the Southeastern United States.
  • Mold can grow in any season, but it's most prevalent in the summer.

The Economic Impact of Mold

  • According to a report by the World Health Organization (WHO), the cost of treating mold-related health problems is estimated to be $3.5 billion annually.
  • Mold can lower property values and make it difficult to sell a home.
  • Mold can result in costly repairs and renovations to remove it.


Mold is a pervasive problem that affects millions of people worldwide. It can cause a range of health problems, damage to property, and even impact the global economy. While mold growth can be difficult to prevent entirely, there are steps individuals and organizations can take to minimize its impact.

Regular cleaning and maintenance, proper ventilation, and prompt remediation of water damage are all effective ways to reduce the risk of mold growth. By taking these steps, we can work towards creating healthier homes, workplaces, and communities for all.


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