Would you be surprised to know that an estimated 70% of houses have mold?
Today, we will be peeking into other startling statistics.
Mold is a subject that homeowners should know more about since it comes with many challenges.
That’s why we made this list of interesting mold statistics for 2025 everyone should know.
Mold isn’t only detrimental to a home’s structural integrity.
It’s associated with several types of health conditions and illnesses, such as allergies and infections.
What is mold?
Mold is categorized as a group of fungi that generate in damp places, like a basement.
It can give off a foul odor, trigger asthma attacks, athlete’s foot, and a plethora of other health complications.
Conversely, without the discovery of mold, we wouldn’t have penicillin or blue cheese without this fungus.
Let’s address some important statistics and facts that may surprise you while informing you what you really should know about it.
Key Mold Statistics
- Mold and Black mold can be kept at bay by keeping humidity levels under 50%.
- $3.7 billion is the average cost of allergic rhinitis associated with indoor mold and dampness.
- Black mold is often categorized as a toxic mold.
- Nearly 600,000 children under 5 years old die from air pollution each year.
- Slime mold lives in the soil as an amoeba.
- 30% of new and remodeled buildings are potentially affected by indoor air quality (IAQ) concerns.
- Mold forms within 24 to 48 hours after water damage occurs.
- 270 species of mold have been found on buildings in Canada.
- Food-related molds are ideally suited for making Camembert, Brie, and Gorgonzola cheeses.
- It’s estimated that 25% of the world’s crops are afflicted by toxic substances referred to as mycotoxins.
Air Pollution and Mold Statistics for 2025
Statistics say that about 70% of homes have mold. Also, around 28% of individuals are genetically susceptible to health conditions related to mold.
These are the kinds of statistics you can expect in this section.
1. About 70% of Homes Have Mold.
If you’re a homeowner, this statistic alone should alarm you. While the exact stats on how many homes have mold has yet to be proven, 70% is an educated estimate from studies performed. Worldwide, most homes have Stachybotrys spores.
Additionally, mold can be found in up to 9% of homes with a terrace, 26% of medical facilities like outpatient clinics, hospitals, and retirement homes, and 18% of elementary to high school facilities.
2. Nearly 600,000 Children Under 5 Years Old Die from Air Pollution Each Year.
Respiratory illnesses among children not only affect their physical development and cognition but also worsens mold-related illnesses.
One in ten children under the age of five dies because of respiratory illnesses connected to mold and air pollution.
Death from mold exposure is immensely frightening for people with weakened immune systems.
Mold spores are responsible for some poor indoor air quality concerns, which can result in mold sickness and other mold-related illnesses.
While anyone with a weakened immune system is vulnerable to mold, children with respiratory conditions, allergies, asthma, or weakened immune systems are especially at risk for dire or fatal mold illnesses.
3. 50% or More Homes in America Are Affected by Mold
Environmental experts claim that environmental mold carries more risk to individuals than asbestos or lead paint.
Hidden mold statistics say that it often skulks around in crawl spaces, behind the walls of showers, and in leaky roofs.
4. 28% of America’s Population Carries Genes that Make Them More Susceptible to Mold-Related Health Conditions.
While not everyone in America will experience a mold-related illness, people who are predisposed genetically carry the highest risk for mold-related chronic and acute health problems.
28% may seem like a small percentage, but considering the population of America, it accounts for about 92,260,000 people.
5. $3.7 Billion Is the Average Cost of Allergic Rhinitis Associated with Indoor Mold and Dampness.
Based on research, the costs associated with allergic rhinitis, asthma, and acute bronchitis that is triggered by mold total $3.7 billion.
$1.9 billion accounts for acute bronchitis, and asthma mortality accounts for $1.9 billion. The cost calculations for this statistic included the cost of the illness (COI) plus the willingness to pay (WTP).
6. Cladosporium, Penicillium, and Aspergillus Account for The Three Most Prevalent Indoor Types of Molds.
These are the top three types of mold that appear inside the home. Homeowners should be aware and consider having regular inspections for mold.
The exact data on how recurrent these molds are is unknown. These molds can live on pipes, windows, ceiling tiles, paint, cardboard, and wood.
Black Mold Statistics & Facts
This section will discuss some alarming facts about black mold.
7. Black Mold Also Goes by The Name, Toxic Mold.
Because of the mycotoxins in black mold, it can cause several kinds of serious adverse side effects like nosebleeds, achiness, memory loss, and can even be fatal.
Stachybotrys chartarum, the species name for black mold is linked to allergy, infection, irritation, and mycotoxicosis.
8. Mold and Black Mold Can Be Kept at Bay by Keeping Humidity Levels Under 50%.
Mold can only thrive where it’s humid and damp. If you have high humidity and damp conditions in your home, or where you live, it’s wise to consider getting a dehumidifier to decrease the humidity levels in your home to below 50%.
Daily cleaning your home surfaces (counters, floors, tables, walls, etc.) can also deter the risk of mold development.
Additionally, avoid putting carpet or rugs in damp rooms in the house like the basement or the bathrooms.
9. Dallas, Texas in The United States Tops the List of Most Allergy Patients with Mold and Mildew Sensitivities at 21%
Riverside-San Bernardino, California comes in a close second at 20%, and Phoenix, Arizona takes third place at 19%, and in fourth place is taken by Los Angeles, California at 17%.
This data is from studies on patients who sought medical care for mold allergies.
Mold on Buildings Statistics
The next few statistics will address mold on buildings all over the globe.
10. 270 Species of Mold Have Been Found on Buildings in Canada.
While mold has thousands of known species all over the world, 270 of them have been found on Canadian structures, including houses and commercial buildings.
Training facilities and grocery stores are strongly recommended to use proper moisture management practices to prevent mold and protect people and the structures.
11. 30% of New and Remodeled Buildings Are Potentially Affected by Indoor Air Quality (iaq) Concerns.
It’s a fact that mold infestations in structures create poor air quality in the building. Poor indoor air quality, or IAQ, contributes to respiratory conditions and other types of health conditions.
One 10-year-old condominium complex had to shell out $4 million in repair and remediation costs due to mold.
12. If You Find a Mold Over an Area of More than Three Square Feet, Consult with A Professional.
Small, minor mold problems can be easily remedied by anyone. However, if the mold area is larger than three square feet, you need to seek professional cleaners.
Larger mold infestations pose more risk to your structure and the people who work or live there.
Therefore, that mold situation should be evaluated by an expert in the remediation field for removal.
13. Mold Forms Within 24 to 48 Hours After Water Damage Occurs.
Statistics confirm that immediate action is necessary after water damage occurs. Water damage can occur due to floods, leaky ceilings, plumbing accidents.
To avoid mold growth be sure to immediately clean carpet spills, stains, and spots. Using less water when cleaning surfaces and carpets will also reduce mold growth risk.
Slime Mold Statistics & Facts
14. One Type of Slime Mold Is Called Dog Vomit.
Slime mold takes on many forms and shapes from having the appearance of a berry to geometric lattices.
One type of mold resembles dog vomit, which is how it got its name. Slime mold is an obscure type of mold, that can be microscopic, or it can grow into a 10- to a 13-foot problem.
15. Slime Mold Is a Single-Cell Amoeba that Lives in Soil.
Slime mold isn’t a plant or an animal. Though it looks like fungus, it isn’t categorized as such. Slime mold has multiple nuclei and is a single-cell organism with no brain.
16. Slime Mold Can Be Any Color Except for Green.
You have probably seen green mold in places, but slime mold is never green. This is because slime mold has no chlorophyll, which is what gives other mold species and plants their green color.
17. Slime Mold Has More than 900 Species.
Slime mold shows up on every continent on the planet. It can be found living in forests, breaking down rotting vegetation, and feeding on bacteria, fungus, and yeast.
You may not even know that you have been around slime mold.
18. The Science-Fiction Movie, “The Blob” Was Probably Mold-Inspired.
If you have never watched “The Blob”, you are missing a story about a fast-growing, destructive amoeba-like alien monster that absorbs the people living in the made-up towns of Phoenixville and Downingtown.
It feeds on its victims, becoming bigger through the movie. In its plasmodial state, real slime mold spreads quickly and looks like a highway or interstate network.
Food Mold Statistics & Facts
19. Bread Mold Is Avoided Through Freezing.
Anyone who has ever eaten bread knows that it gets moldy. Usually, bread mold is white or green. This kind of fungus can be avoided if you freeze your bread.
If you put bread in the refrigerator, it will slow mold growth, but it can still develop, grow, and spread. It’s recommended to freeze bread and take out slices as you need them.
20. Bread Mold Is Hazardous and Can Cause Serious Infections.
While it’s not common in healthy people with strong immune systems, the statistics on bread mold reveal that bread mold can trigger allergies and cause serious infections for people with weakened immune systems.
If you see fuzzy mold on your bread throw it away and don’t eat it. Bread mold consists of Rhizopus, Aspergillus, and Fusarium molds.
Bread mold may not only trigger allergies, but it may also cause chronic respiratory problems like asthma.
21. It’s Estimated that 25% of The World’s Crops Are Afflicted by Toxic Substances Referred to As Mycotoxins.
Nuts, grains, grape juice, celery, and apples can produce mycotoxins. One such mycotoxin found in field corn and peanuts is called Aflatoxin.
Aflatoxin is affiliated with illnesses like aflatoxicosis that can affect humans and domestic animals.
22. Food-Related Molds Are Ideally Suited for Making Camembert, Brie, and Gorgonzola Cheeses.
Not all mold is evil. Food mold is beneficial for making varieties of cheese. It can develop inside or outside the cheese.
Stilton, Gorgonzola, and Roquefort cheeses are referred to as blue-veined cheese created by adding Penicillium Roqueforti spores.
Remember, molds used for creating cheeses are safe for consumption.
Mold, Asthma and Health Statistics
23. Asthma Risk Ascends 30% to 50% from Mold Exposure.
Because mold adversely influences indoor air quality the risk of asthma is higher. 30 to 50% higher risk comes with mold exposure for asthma and other respiratory problems.
Long-term exposure to mold in the workplace where the IAQ is poor may worsen asthma or respiratory conditions.
24. The Most Common Molds that Trigger Allergies Are Stachybotrys, Chaetomium, Fusarium, Alternaria, Penicillium, Cladosporium, Mucor, and Aspergillus.
Like pollen, not all mold spores are allergenic. The most common allergenic indoor molds are Stachybotrys, Chaetomium, Fusarium, Alternaria, Penicillium, Cladosporium, Mucor, and Aspergillus.
25. Childhood Mold Exposure Increases Asthma Risk.
Dampness and mold exposure are common, resulting in an uptake of between 18% and 50% due to the number of buildings that are damp and have mold nowadays.
Childhood asthma is also more prevalent in boys than girls.
FAQs
How Much Mold Exposure Is Considered Harmful?
There is no minimum or maximum exposure when it comes to mold when you’re susceptible to certain health conditions.
Mold exposure can occur through touch, consumption, or inhaling mold spores.
Mold not only adversely affects buildings but can also be damaging to your health.
Whether you suffer from a weakened immune system, asthma, allergies, or any respiratory condition or not, it’s recommended that you thoroughly clean up mold before exposure can become hazardous.
You should not take chances with mold.
What Symptoms Can Present from Mold Exposure?
Depending on the mold species and amount, mold exposure, especially black mold exposure, can present with nasal stuffiness, coughing, sore throat, itching eyes, or skin rashes.
How Do You Treat Mold Allergies?
The best way to treat mold allergies is to eliminate the source.
You can also wear allergy masks like you see people wear when mowing their lawn.
If mold is growing inside your home, consider having your home inspected and remediated as soon as possible.
If you see or smell mold, it may already be harming your structure or your health.
Alternatively, you can consult with an allergist about immunotherapy and other treatments.
How Long until Mold Causes Side Effects?
Nothing is known about how long it takes to be affected by mold exposure.
Statistics show that mold may not affect you at all.
However, if you have preexisting health conditions you could have a severe asthma attack or reaction.
Currently, no test exists that detects if you have been affected by mold.
How Do You Know if You Have a Mold Problem?
To find out if you have mold in your home look for small, white, thready clusters or small clusters of black spots on your bathroom or basement walls.
If you see either of these growths, you have mold. You may not always see mold, but you may smell mold.
If your home smells musty then mold is growing in your walls.
When mold grows inside your walls it’s harder to detect without an expert. Some mold is hidden, so you will not detect it through smell or sight.
It’s recommended that if you suspect mold, consult with your local water remediation service.
Conclusion
Mold comes in a variety of species and types that can range from harmless to deadly.
Mold exposure for some people can cause chronic health conditions or other illnesses.
Not everyone is susceptible to mold, but for people who are a variety of symptoms can present.
Some symptoms of mold exposure include cough, throat irritation, and nasal stuffiness.
People who are not sensitive to mold are not likely to have any symptoms.
Some mold spores are deadly, like black mold, but mold is still something that homeowners need to keep their eyes on to protect their structure and family.
We hope that these mold statistics, facts and figures have given you some things to think about when thinking of mold.
Whether you work in construction or live in a humid area, mold is something you should learn more about and be watchful for it.
Sources
| AchooAllergy | Berkeley | BulbApp |
| CCOHS | CDC | EHA Group |
| Ferro Canada | Healthline | Healthline |
| Healthline | Medical News Today | Molekule |
| PBS | Servpro Potts Ville | This Old House |
| Truth About Mold | USDA | Harvard |
