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18+ Mold Statistics You Should Know [2023]

Written by, Jalluri

Updated March, 14, 2023

Mold seems to be a huge problem for many households worldwide. Why is that? What are we doing wrong? And why is it so difficult to get rid of it?

Let’s get to the core of this problem and learn more about it. To do so, we’ve gathered some good-to-know mold statistics.

Fascinating Facts of Mold (Editor’s Pick)

  • A stunning number of seven million deaths are connected to indoor and outdoor air-related issues.
  • Over 3 bn people around the world are directly affected by home pollution.
  • Exactly twenty-five percent of the food crops worldwide are mold affected.
  • The worldwide mold growth rate is roughly seventy percent.
  • If the mold size goes up to 10-square feet or more, give a call to a mold remediation specialist.
  • Precisely, 28 percent of American citizens carry the mold gene, which is equivalent to over 80 million people.

What is mold?

Mold is, in fact, a fungus that you can find anywhere where there’s a presence of moisture and oxygen. Mold growth most commonly happens on:

  • Wood
  • Paper
  • Carpet
  • Foods
  • Insulation
  • Inside the house (sink, toilet, basements, microwave, bathtub, etc.)

How do mold spores affect people?

Mold spores affect people that happen to have overly sensitive immune system responses. The body identifies mold spores as a sort of invader; hence it automatically produces antibodies to fight it.

The symptoms of mold allergy include:

  • Sneezing
  • Runny/stuffy nose
  • Cough and watery eyes
  • Scaly skin
  • Itchy eyes
  • Skin rash
  • Throat irritation

What are the three most common types of indoor molds?

The three most common types of indoor molds include:

Aspergillus: a kind of mold that causes Aspergillosis infection. It is a harmless (for the most part) mold that is present both indoors and outdoors. The fungus doesn’t affect healthy people. On the other hand, people with a weakened immune system can get sinus and lung infections after inhaling Aspergillosis spores.

Cladosporium: This type of mold is held responsible for triggering allergies and asthma in people. However, in rare cases, the mold can also cause serious lung infections. This type of mold, too, grows both indoors and outdoors.

Stachybotrys: black mold or toxic black mold. Stachybotrys are not more dangerous than other types of molds. They grow in warm and moist environments, such as the kitchen, basement, and toilets. This type of mold can also grow on paper, wood, and dirt.

General Statistics

1. What percentage of houses have mold?

(Sources: Wilson Web Psychics, This Old House, FindAnyAnswer, ComfyLiving)

No less than seventy percent of homes, on a global level, are mold-infested.

Though there is no official data to give a precise number to how many homes are mold invaded, there is still a pretty good estimation to round up the numbers. Following the latest mold statistics, the most rational analysis points to a minimum of 70 percent of the houses have mold.

The Moldy experts unveiled the fact that just in the USA, over 50 percent of the houses have mold. And shockingly, as much as 28 percent of people (or 100+ million American citizens) carry the gene that makes them vulnerable to mold-related health issues.

2. How many deaths occur due to mold?

(Sources: World Health Organization, ABC News, Realtime Labs)

A stunning number of seven million deaths are connected to indoor and outdoor air-related issues.

The World Health Organization (2014) published reports stating as many as seven million deaths a year are caused by polluted air. Among the others, they said even though mold sometimes may be invisible to the eye, it still can take a deadly toll on health.

Can mold kill you? It seems like it can. For instance, let’s take the Seattle Children’s Hospital mold-related incident. In 2019, the Seattle Hospital’s CEO admitted to 6 mold-related infections that ultimately led to deaths, in a period of twenty years. Apparently, the hospital’s central air conditioning systems spread mold throughout the operating rooms. When mold combines with a fragile immune system or open wounds, it can be a deadly combination, especially for children.

It comes as no surprise that one in ten children (under the age of five) loses life because of mold illnesses and respiratory diseases.

3. How many people are affected by black mold?

(Sources: Realtime Labs, healthline, Air Things, Moldman)

A relatively small percentage of people are affected by black mold.

A report published by Moldman states that there are no confirmed cases of black mold death. On the contrary, many reports say that black mold or Stachybotrys is unlikely to make healthy people sick. The two groups that it affects are the elderly and very young children. Also, following research (2017), we understand that there is no whatsoever verification that black mold exposure (in particular) is the sole reason to blame for people’s specific health problems.

Here are some black mold symptoms you should know: throat irritation, coughing, runny nose, itchy eyes, etc.

4. How much does it cost to fix it?

(Sources: HomeAdvisor, HomeServe, houselogic)

Generally speaking, mold remediation costs anywhere between $500 and $4.000.

The price is determined per square foot, and it varies highly from one company to another. For instance, a mold cleaning solution goes from $1 to $9 per square foot, while mold removal costs $1.25. And, if you include a HEPA vacuum, you’ll get charged 90¢ per square foot.

However, some reports say the price for complete mold removal can reach up to $6.000 if the problem is highly severe since a contributing factor is also where the mold formation takes place.

The price primarily depends on the amount of mold and whether you’ll opt for professional help or a DIY solution. Furthermore, if you choose a professional mold removal, the price will probably vary from one cleaning service to another.

If you have mold or fungus in-house, the removal can take anywhere between one to seven days, depending on the severity of the problem. You can also have a home warranty company do a thorough inspection of your home; for example, Choice Home Warranty can do a mold check-up for you.

5. How many are affected by home pollution?

(Sources: Our World in Data, Mana Medical Associates, World Health Organization, The Conversation)

Over 3 bn people around the world are directly affected by home pollution.

The latest reports on home pollution indicate that a terrifying number of three billion people are affected by home pollution. One would think that breathing polluted air into your home isn’t possible, but it is. The source of home pollution comes through cooking, heating, and lighting with traditional domestic fuels (open fire, charcoal, wheat straw, coal, etc.).

Furthermore, IHME (The Institute for Health Metrics and Evaluation) stats from 2017 indicate the lives of no less than 1.6 million people were cut short prematurely because of indoor pollution. This fact represents precisely three percent of the deaths on a global level. Moreover, these numbers confirm that as much as six percent of these deaths happen in countries with poor income.

It might come as a shock to you, but as per the EPA, the indoor polluted air is two to five times worse than the outdoor air.

6. Types of molds and their effect on people

(Sources: TheAllergyStore.com, AerIndustries, RestorationMaster, IndoorDoctor, CDC, ck-12)

There are over 100.000 distinctive kinds of mold.

And even with 100.000 different types of molds, no more than five of the most toxic molds can be usually found inside one’s home. Those are:

  • Cladosporium (causes asthma-like symptoms and fever)
  • Penicillium (extreme exposure can lead to severe infections, it can even affect the bone marrow)
  • Alternaria (causes allergy-like reactions and provokes asthmatic attacks)
  • Aspergillus (allergic reactions, respiratory-related issues, and infections, lung inflammation)
    and Stachybotrys (respiratory issues, asthmatic attacks, chronic sinus problems, depression).

While some of those mentioned above can cause mold allergy-like symptoms, others can lead to potentially deadly illnesses.

Sporothrix schenckii is another type of fungus that causes Sporotrichosis, a mold skin infection. The infection is not deadly. However, if you don’t get it treated, it can cause bumps for many years. There are outdoor molds as well that play a part in the natural surroundings. A water mold, known as Oomycota (Oomycetes), resembles fungi and is economically important as an aggressive plant pathogen.

7.  How much mold exposure is harmful?

(Sources: EnviroMed Clinic, CMA, Dry Effect Restoration Services)

Any amount of mold exposure is harmful to our health.

The mold itself is not dangerous, but the toxic substances it releases in the form of spores are considered unsafe. Additionally, the severity of the damage to human health depends on the level of mold exposure.

For most people, mold allergy provoked is what makes them sick. However, the intensity of mold allergy reactions varies from mold to mold and person-to-person.

Consequently, that is why some people experience no symptoms whatsoever, while some are at a higher risk of developing chronic asthma or other chronic illnesses. Nevertheless, mold allergies and mold poisoning are the two main concerns caused by invasive mold exposure.

Food Mold Stats

8. What percentage of food crops are affected by mold?

(Sources: FAO.org, healthline, IntechOpen)

Exactly twenty-five percent of the food crops worldwide are mold affected.

As per the Food and Agriculture Organization (FAO), as much as 25 percent of the food crops worldwide are affected by mycotoxins—toxic compositions, that specific kind of molds, are known to produce them naturally. This raises a red flag since agriculture is equally vital for humans and livestock. Additionally, recent reports speculate the mycotoxins to overtake roughly around 60% to 80%. Furthermore, this kind of agricultural threat will damage our economy too. Though, precise estimation of these damages would be hard to assess.

Whereas different estimations point out that aflatoxin contamination has done severe economic damage to the corn industry. In other words, the USA suffered losses of up to nearly 1.7 bn.

9. How dangerous is bread mold?

(Sources: Well+Good, GreenMatters, Business Insider, Thrillist, healthline)

Bread mold is so dangerous that there is no such thing as a ‘’clean.’’

Moldy bread is nothing but bad news. Meaning, you shouldn’t consume it – the visible spots should be your warning sign. Not only can it cause an allergic reaction, but it goes as far as causing serious infections.

If you notice some spots on the bread, do yourself a favor and throw the whole loaf. Because, if there’s mold spreading on one side of the slice, there must be mold throughout the whole loaf of bread.

Slime Mold Stats

10. How many species of slime mold are found?

(Sources: PBS NewsHour, Quanta Magazine, Britannica, New Forest National Park Authority, TX Plant Clinic)

There are 900+ species of slime mold around the world.

Interestingly enough, this type of mold isn’t regarded as a fungus. Instead, it is an amoeba (a one-cell organism). And, they have not been considered a danger to humans or animals.

However, the dusty mold spore can irritate allergies and asthma in some people. It looks like an animal (mainly because it moves), but it is just a soil-dwelling amoeba. It’s a one-cell organism and consists of an acellular mass of creeping gelatinous protoplasm.

Here’s a fun fact, there’s a slime mold known as ‘dog vomit’ (because of the similarities in appearance of the actual dog vomit and the amoeba).

Building Mold Stats

11. What percentage of houses with mold?

(Sources: GOV.UK, Wilson Web Physics, Comfy Living, Envirovent, Water Damage Advisor)

The worldwide mold growth rate is roughly seventy percent.

Though there is no way to establish an actual mold growth rate, the latest known reports indicate around 70 percent of mold-infested houses on a world level. Mold affects both undeveloped and developed countries.

For example, just in 2019, the UK Ministry of Housing published a report stating that three percent of British households are facing damp-related issues. At the same time, another report said that one in five British homes suffers from mold. Hence, these are a bit less than fifty million homes and buildings

Nonetheless, it seems like the situation in America is worse than in the UK—as twenty to fifty percent of houses in America have some type of mold issue.

12. What is the impact of building molds in the US?

(Sources: Realtime Labs, OCCU-TEC)

Nearly forty-five million buildings in the USA have dangerous mold levels.

Let’s take, for instance, the case with the well-reputed local builder in Cincinnati, Ohio. He was forced to reconstruct and rebuild as many as a hundred brand new homes because of mold. Consequently, the owners of these new homes demanded thousands of dollars for renovation.

Whereas another similar case took place in New York. Where owners of two apartment buildings have 125 lawsuits coming to get them, and more or less an 8 bn damage to repay the people living in those buildings.

Here is a helpful tip that you shouldn’t ignore: cleaning your bathroom walls regularly and sanitizing humidifiers can help keep commercial properties safe from molds.

Mold not only causes damage in structures to buildings but is also associated with wood destruction. One of the most shocking mold statistics to note is that mold destroys more wood every year than fires and termites together.

And if you have appliances that may be destroyed by mold, contact Clinch Home Warranty and schedule an appliance repair (keep in mind that their warranty doesn’t cover mold-related issues).

13. How many kinds of building molds are there?

(Sources: Comfy Living, b-air.com, FindLaw, Ideal)

The number of different kinds of mold found inside buildings is no more than 270.

According to a report by FerroCanada, experts were able to find 270 different mold species in buildings. And these are the five most common building molds: Cladosporium, Penicillium, Aspergillus, Alternaria, and Stachybotrys.

Molds present in the buildings can be both hidden or visible. However, they are often caused by flooding, leaky roofs, rising dampness, water leaks, bridging, condensation, and other indoor-plumbing problems.

Additionally, here’s a tip, you can contact Select Home Warranty (one of the best home warranty companies in the US) to fix any roof leaks and other plumbing problems and reduce the risk of mold formation.

14. What percentage of buildings is remodeled with IAQ issues?

(Sources: Ferro Canada, Manko Gold, Parliament NSW.GOV, US EPA)

More or less, thirty percent of buildings with IAQ (Indoor Air Quality) issues are remodeled.

Of course, bad indoor air quality is associated with mold. When the level of mold spores increases, the indoor air quality gets affected, thus, transmits people asthma, allergies, and causes respiratory problems.

This shouldn’t be a surprise since more than 70% of commissioning pros say buildings have serious duct leakage. Furthermore, other common reasons for IAQ problems are indoor air contaminants such as bacteria, dust, gases, vapors, odors, and poor indoor environments (humidity and poor air circulation).

Nonetheless, these issues have a significant negative impact on the economy—loss of productivity and medical expenses altogether are damaging the economy for up to eight billion a year.

15. When to contact a professional in case of mold?

(Sources: Restoration Master Finder, The Family Handyman, US EPA GOV)

If the mold size goes up to 10-square feet or more, give a call to a mold remediation specialist.

There are many reasons to consider calling a professional mold removal service. For instance, a musty smell, black spots, large mold-infested indoor/outdoor surfaces, decaying wood covered in mold, etc. The best thing to do is call a remediation professional if someone at your home has asthma, or a weakened immune system caused by HIV, transplant, or any terminal disease.

Mold Impact Stats

16. The annual cost of allergies caused by molds in the US

(Sources: ACAAI Public Website, AAFA.org)

Recent reports state the annual cost of allergies caused by molds in the US is precisely eighteen billion.
Apart from the reports on allergies caused by annual costs, we look into the food allergy costs too, which are estimated to be a shocking $25 bn yearly.

Allergy is one of the leading and most overlooked diseases in the United States. Every year, 50+ million Americans put up with allergies, making it the sixth leading cause of illness in the country.

Further data show that more than 8% of kids in the USA under the age of 18 suffer from hay fever, while no more than 10% are greatly troubled by respiratory allergies. Over 5% of kids suffer from food-related allergies, and almost 12% are affected by skin allergies.

17. What percentage of the population is susceptible to mold illness?

(Sources: The Mold Guy, Surviving Mold)

Precisely, 28 percent of American citizens carry the mold gene, which is equivalent to over 80 million people.

People with the HLA-DR gene are generally susceptible to biotoxin illnesses. The most common mold biotoxin symptoms include headache, fatigue, cognitive impairments, cough, shortness of breath, chest pain, sexual dysfunction, unusual muscle aches, etc.

According to Dr. Scott McMohan, MD, almost all the doctors in the US are treating mold illness. The only difference is that they don’t realize it as they don’t have the training to identify mold death and disease.

Interesting Facts

18. How many people have mold-related asthma in the US?

(Sources: Wiley Online Library, Realtime Labs, Truth About Mold, HealthDay, AAFA)

Nearly 5 million asthma cases are directly linked with humidity and household mold exposure.
The Center For American Progress (2016) published that roughly 40 percent of asthma attacks are caused due to the presence of dust miles, rats, and mold in the house. Additionally, a report by Michael Pinto states that infants exposed to mold in their surroundings have three times higher chances of developing asthma than those who haven’t been exposed to mold.

A report published by the EPA and Berkeley National Laboratory (2007) stated 4.6 million out of almost 22 million cases of asthma were linked to humidity, and mold exposure in the house.

Ultimately, mold statistics show that asthma and mold are closely related.

19. How many people have mold-related sinus infections?

(Sources: EverydayHealth, ScienceDaily, Medscape, North Atlanta Ent & Allergy, Realtime Labs)

One out of seven adults in the US suffers from sinus infections.

Every year, over thirty million American citizens are diagnosed with sinusitis. Interestingly enough, in 1999, Mayo Clinic researchers found that more than 90% of persistent sinus infections were linked to mold rather than any other causes, like allergies.

They conducted a study on more than 200 patients experiencing sinus and found fungus in 93 percent of the mucus. The research pointed to mold-infested homes and work surroundings where mold is found to be responsible for up to nine out of ten sinus cases.

20. How many infants/children are affected?

(Sources: WHO, Water Moldfire)

A total of 600.000 children worldwide lost their lives because of acute respiratory infections.

Following the WHO reports from 2016, as many as 600.000 children lost lives because of the complications caused by acute respiratory infections. Further reports from WHO revealed some shocking numbers. Among some is the fact that roughly around a billion children on a global level are in direct exposure to indoor polluted air; This is primarily due to cooking with unhealthy fuels and unsafe technology. Indoor and outdoor air pollution is responsible for over 50 percent of lower respiratory infections in children under the age of five.

Looking further back, a 2015 study on Allergy, Asthma, and Immunology Research unveiled the fact that almost 10 percent of the overall population, children as well, are sensitive to mold—Thus, making them more prone to mold allergy reactions.

Final Verdict

As per later and more recent mold statistics, molds are found anywhere.

All that is needed for mold formation is moisture and oxygen. To avoid it, make sure you keep the house dry at all times and often ventilate it. Make moisture management practices a must and gets mold testing done at least once a year.

However, if you do believe that there is a hidden mold threat (weird smell or black spots in unusual places/furniture), or you have a family member who can easily manifest its symptoms, don’t waste any time, get your home tested and professionally cleaned ASAP.

To wrap it up. Mold triggers respiratory illnesses that can sometimes turn deadly, and there are numbers and research that support this statement