Indoor air quality (IAQ) refers to the air quality in our homes and buildings. The average person spends more than 90% of their time indoors breathing air that is potentially bad for their health. In fact, the EPA estimates that concentrations of some pollutants in an indoor environment are often 4-5 times higher (in some cases as much as 100 times higher) than outdoor levels. Many of these pollutants are odorless, colorless, and invisible to the naked eye, making them difficult to identify and remove. As a result, they are often overlooked as potential triggers for a wide range of health issues. 

Simply put, the air in our homes and buildings can either protect our health or make us sick. 

For a more thorough analysis of the health effects that occur from exposure to mold and water-damaged buildings, please visit our "Research" tab . 

Even though the air in our homes or buildings may look or even smell clean, it can be filled with a wide range of pollutants. These can include mold, bacteria, dust mites, dander, carbon monoxide, carbon dioxide, radon, formaldehyde, lead, asbestos, and volatile organic compounds (VOCs). These pollutants enter our homes through various methods, such as through windows, doors, ventilation systems, the furniture we buy, the paints we use, and the appliances we run. It’s important to note that many of these pollutants may have no color or discernable odor. A good Indoor Environmental Professional (IEP) or other appropriate professional may be required to determine the presence or absence of these pollutants.

To learn more about how to find a good IEP, please visit Step 1 of our Mold in the Home feature or watch "Mold Remediation Part 1: Hiring the Right Time & Order of Events."

While it’s not always possible to fully avoid all indoor pollutants, there are important steps that can be taken to eliminate and reduce exposure to these substances. Those steps may include:

Source control and removal: This is often the best way to limit exposure. The goal should always be removal when possible. For example, it is better to safely remove mold and water damage as opposed to trying to kill it or cover it up. Some pollutants cannot be removed, and mitigation or abatement may be necessary, such as is the case with radon and even lead.  Be intentional and mindful when selecting and using building materials, furniture, cleaning and personal care products so as to limit exposure to problematic VOCs. Be sure to maintain appliances such as stoves, ovens, water heaters, etc., to decrease the risk of accidental emissions. 

To learn more about effective mold remediation, please watch our interview, "Mold Remediation 101" and download our free, consumer friendly guide "Mold Remediation At a Glance."

Increased ventilation: This involves increasing the amount of outdoor air that is brought into the home or building. At its simplest, opening doors and windows for 10 minutes a day, as climate and weather allow, can bring in fresh air to dilute concentrations of these indoor pollutants. Always use kitchen and bathroom fans during cooking and bathing in order to exhaust moisture and pollutants outdoors. Newer and more energy efficient homes may require mechanical assistance from energy recovery ventilators (ERVs) which are designed to bring fresh air from outside into your home or building.

To learn more about improving ventilation, please watch our interview, "Ventilation Designs for Healthy Homes," "Learn About the V in HVAC: Ventilation Basics," and "The CO2 Connection: A Hidden Clue to Indoor Air Quality."

Air cleaners/purifiers/filters: This involves using filtration to remove certain pollutants from the air. Upgrading the filter on your heating and cooling systems to the highest rated MERV filter your unit will allow will help reduce contaminants that circulate throughout the home. Additionally, there are a variety of air purifiers and air cleaners available today that can be used to reduce these indoor pollutants. The effectiveness and cost of these types of machines vary greatly, so do your research before purchasing. 

To learn more about air purifiers, cleaners, and filters watch "Understanding Air Purifiers and Cleaners" and "The Nitty Gritty of Good and Bad HVAC Filtration."

Mold growth in nature is a healthy and normal part of the ecosystem; however, mold growth in your home is not. Unlike in nature, our homes lack the natural forces to keep mold in check. In fact, many of our buildings have excess humidity, stagnant air, minimal air flow, and are constructed with building materials made of organic matter (like drywall!), which is an ideal food source for mold. 

So, while it’s true that there is always some level of mold spores in the air (both indoors and outside), it’s important to take steps to safely remove any mold growth and water damage that occurs indoors. This includes removing any byproducts created by that mold growth such as microbial volatile organic compounds (mVOCs), mold fragments, and mycotoxins. Don’t forget to address the moisture source, or the problem is likely to return. 

For step-by-step support navigating the inspection and remediation process, visit our Mold in the Home feature or download our free, consumer friendly guide "Mold Remediation at a Glance."

When the conditions are right (time, moisture, food source, and spores), mold can begin to grow in as little as 24-48 hours. Unfortunately, it’s not the only thing that can grow and flourish. The environment created by water-damaged environments is complex. In these types of environments mold spores, fungal fragments, mycotoxins, bacteria, and microbial volatile organic compounds (mVOCs) are just a few of the pollutants that can fill the air and affect our health. 

To learn more about this complex ecosystem, check out Dr. Jack Thrasher and Sandra Crawley's  paper here, and Dr. Janette Hope's paper here.

According to the EPA, “dead” or “dormant” mold is still a health hazard.  Additionally, many of the byproducts created by mold such as mycotoxins, microbial volatile organic compounds (mVOCs), and fungal fragments are not alive and can’t be killed. Further, a dried or dormant mold colony may pose a larger health hazard as it’s more likely to break apart into smaller fragments if disturbed. These tiny fragments are then more easily able to bypass our body’s natural defenses and get into our lungs and bloodstream. Mold remediation should always focus on removal.

To learn more, watch "The Truth About Dormant Mold."

To learn more about the inspection and remediation process, visit our Mold in the Home feature and download our free, consumer friendly guide "Mold Remediation At a Glance."

No. Killing is often ineffective for a number of reasons and the goal should always be removal. For starters, dead mold is still a health hazard according to the EPA. Further many byproducts created by mold, such as mycotoxins and microbial volatile organic compounds (mVOCs), are not living, so they can’t be killed. 

More recently, government agencies like OSHA and the EPA have stopped recommending the routine use of bleach for cleaning up mold for good reason. While bleach may be effective on nonporous materials like glass and tile, it is not as effective on semi porous and porous materials like drywall or wood. Often, bleach will remove the appearance and color of mold from these building materials but leave behind the root-like structures that have grown into the surface. Additionally, commercial bleach is over 90% water. Once the chlorine evaporates, it leaves behind water that can create additional problems and foster more growth. 

Finally, painting over and encapsulating mold growth is often not very effective. Not only can encapsulants fail, but many popular mold-killing paints and encapsulants state in the fine print that they need to be used on clean and dry material, or it voids the warranty. These chemicals can also add additional VOCs to the air that may be problematic for some individuals.

To learn more, read "Why Can't I Just Spray the Mold Away."

Potentially. Most people are familiar with the traditional “musty” smell associated with mold growth. If you smell mold, you are likely smelling microbial volatile organic compounds (mVOCs), which are gasses produced when mold and bacteria is actively feeding. However, mold doesn’t eat all the time. It goes in and out of feeding cycles depending on various conditions such as available moisture and food source. This can explain why people only notice an occasional odor, such as after a shower or storm. It is also important to note that you can have actively growing mold with no detectable odor. Unfortunately, you can’t rely on the “sniff” test alone to tell you if you have a problem.

According to the EPA, if you have a musty odor, it’s a sign of a current problem and should be promptly investigated.

To learn more, watch "What's That Smell: MVOCs and Mold" or "The Hidden Dangers of Moldy Smells."

Yes, mold behind walls, ceilings, and floors can affect the air in your home, and as a result, your health. This is because walls, ceilings, and floors are not hermetically sealed, meaning there are gaps and cracks present.  These openings can be from light outlets, electrical switches, recessed lights, and other penetrations. Even the gap where your drywall meets the floor can allow for movement of these particles. While these openings may seem small to us, they are big enough to allow particles such as spores, fragments, and mycotoxins out and into your living spaces. 

To learn more, watch our Ask Change the Air episode "Can Mold Behind a Wall Impact Your Living Space." 

Yes, mold in your basement, crawlspace, or attic can affect the rest of your home. This is because air currents are constantly moving throughout your home due to factors like wind, HVAC systems, and stack effect. 

Stack effect is an often-overlooked factor when we think about the way air moves throughout our home. The tiny cracks and openings in our homes and buildings allow for pressure differences to occur between inside and outdoors. In the winter, warm air rises, and the pressure pushes that warm air out the top level of the home and sucks in cool air from lower levels like the basement, crawlspace, or first floor. Stack effect is greatest in the winter due to the larger temperature differences, but it still occurs in the summer. However, in the summer, the reverse occurs with hot air being pulled in through the upper level, and cool air being pushed out the lower levels. This can be one reason an upper floor is warmer in the summer. 

Due to stack effect and other factors that influence air currents, the air in your home (and any pollutants within it) is constantly being moved throughout the building. The simplest way to illustrate how easily air moves throughout our homes is to imagine that someone burnt toast in your kitchen. It doesn’t take long for the odor to find its way into other rooms and floors in your home as a result of these air currents.

To learn more, watch "Testing Your Home For Mold."

Check out other common misconceptions about mold by watching our interview "Myths and Misconceptions."

It is never a good idea to try and conclusively identify the type of mold simply by looking at it. The only way to know for sure is to have it tested. There are over 100,000 species of mold. Mold comes in a variety of colors and can be pink, green, brown, black, red, white, gray, and everything in between. A specific species of mold may be several different colors. Further, different species of mold can be the same color! For example, Stachybotrys (a.k.a. “black mold”) can be colors besides black. There are also many different species of mold that can be black, including Cladosporium, Alternaria, and of course, Stachybotrys. The color of mold can be affected by several things, including species, age, and its food sources. Finally, no one can look at a patch of  mold and tell you if it's producing mycotoxins, a poisonous substance produced by certain kinds of mold under certain conditions. So, it’s a red flag if someone tells you, “I can tell by looking at it that it's not a dangerous kind of mold,” or  “It's not black, so it's not harmful.” Unless that person has microscopes for eyes, it’s just not possible to conclusively determine the type of mold, or if the mold is a serious health hazard.

To learn more, check out our interview, "Mold Matters: Exploring the World of Fungi."

Check out other common misconceptions about mold by watching our interview "Myths and Misconceptions." 

Mildew refers to a certain type of fungus. The term mildew is often used generically to refer to mold. Unfortunately, some people downplay mold growth by calling it mildew. Don’t be fooled. If the conditions are right, mold and mildew can grow and cause health issues. If you see mold or mildew growing in your home, it's worth determining the extent of the problem and finding appropriate solutions. 

To learn more, watch our interviews ""Myths and Misconceptions" or "Moldy Misconceptions."

No. By definition, a toxigenic mold is one that is capable of producing mycotoxins, a secondary metabolite produced by certain kinds of mold under certain conditions. Not all molds are capable of producing mycotoxins, but that doesn’t mean those molds can’t cause health problems. Some molds can be allergenic and even pathogenic. There is no way to visually determine if a mold is toxigenic or if it is currently producing or has produced mycotoxins in the past. Testing is always needed to conclusively confirm the species of mold. Any mold growth in your home, regardless of species, should be safely removed and the water source corrected. 

To learn more, watch our interviews ""Myths and Misconceptions" or "Moldy Misconceptions."

Only certain molds under certain conditions produce secondary metabolites known as mycotoxins. Mycotoxins are a poisonous chemical whose primary purpose is self-defense. Similar to how thorns protect a plant or claws protect an animal, mycotoxins protect a mold colony. 

However, just because a mold can produce mycotoxins, doesn’t mean it always does. Creating mycotoxins is metabolically expensive for mold, meaning it takes a lot of energy for a mold to produce them. As a result, mycotoxins are made only under certain conditions, such as when certain other molds or bacteria invade the area. When mycotoxins are created, they ooze over the defending mold colony and even the immediate surrounding building material, much like lava oozes over a volcano.  

Contrary to popular belief, mycotoxins are not a gas. They are a liquid-like substance. Mycotoxins are molecules that absorb into particles as small as 0.01 microns. They travel on air currents while attached to mold spores, fragments, dust, etc. Exposure to mycotoxins can occur through eating contaminated foods, inhaling contaminated air, and through skin contact. It is not possible to tell if a mold is producing mycotoxins simply by looking at it. 

While scientists have discovered hundreds of different types of mycotoxins, there are likely many more to be identified as research progresses. It’s worth noting that the same mold species can produce more than one kind of mycotoxin, and different mold species can produce the same kind of mycotoxin.  

While the amount of research on mycotoxins has grown significantly over the past few decades, there is still a lot to learn. What we do know is that exposure to mycotoxins can cause a number of serious health conditions and even death. 

To learn more about mycotoxins, watch "Mold Matters: Exploring the World of Fungi."

To learn more about the health effects of mold and mycotoxins exposure, visit our Research Tab.

Yes, you can still have mold and other microbial growth even without a major leak or flood. Mold needs four things to grow: mold spores, moisture, a food source, and time. The moisture source can come from many other things besides leaks and floods. For example, relative humidity above 60% can provide enough moisture for certain species of mold to grow on your belongings and building materials. Condensation on windows, HVAC ducts, and other building materials can provide an ideal moisture source as well. Overflowed toilets, tubs, spills, along with improperly ventilated bathrooms and kitchens can add considerable moisture to the environment if not properly managed and addressed. Finally, exterior issues such as improperly installed windows, siding, roofs, and sprinkler systems, along with poor drainage and grading, can create moisture issues that impact the interior of the home.The bottom line is, moisture is moisture. Mold and other microbial growth doesn’t care where it comes from. 

This is a simple question that has a rather complicated answer. If you see or smell mold and water damage, the problem is more obvious and warrants proper investigation. More often than not though, the problem is not so obvious. This is because mold and water damage is often hidden under floors and behind walls and other building materials such as tile. Further, places like attics, crawlspaces, basements, and HVAC systems are prone to water damage and mold but are often overlooked, dismissed, and rarely monitored on a regular basis. Finding hidden mold and water damage requires a bit of detective work. In fact, one of the secrets to looking for mold is not to look for mold, but for the 5 signs of water damage.  

With a little effort and armed with the right information, a homeowner or renter may be able to find many of the problem areas within their home on their own. However, it can be wise to hire a knowledgeable Indoor Environmental Professional (IEP) to conduct a multipronged approach when investigating a home for mold, water damage, and other indoor pollutants. Generally speaking, there are four key parts to any good investigation: a thorough investigation of the entire home (including hard-to-reach areas like attics and crawl spaces), a comprehensive analysis of the history of the home (including past or current water events), strategic use of testing and tools, and a thorough inventory of the health symptoms and complaints of the people in the home. 

Word of caution: do not rely on any single test (petri dish, air, dust, etc.) to tell you if your home has a problem. Each test has specific strengths and limitations, and relying only on a single test or series of tests is likely to give you an incomplete and inaccurate understanding of your home. Any testing should be combined with a thorough investigation of the rest of the home. 

To more about  how to find  a knowledgeable IEP to conduct a thorough inspection, please visit Step 1 of our "Mold in the Home"  feature or watch "Order of Events & Hiring the Right Team."

An Indoor Environmental Professional (IEP) is a general term (not a specific certification) used to describe someone who performs indoor environmental inspections and assessments of a building. This is the person you hire before hiring a remediation company. They provide an independent assessment of what might be going on in the home. Their investigation should include four key areas: a thorough investigation of the entire home (including hard-to-reach areas like attics and crawl spaces), a comprehensive analysis of the history of the home (including past or current water events), strategic use of testing and tools, and a thorough inventory of the health symptoms and complaints of the people in the home. 

Unfortunately, too many IEPs do not use a multipronged approach to their investigation and instead rely only on taking ambient air samples from the center of various rooms. It’s best not to hire this kind of IEP as this type of investigation is likely to provide an inaccurate and incomplete picture of what might be going on in the home.

If remediation is needed, the IEP can write a remediation plan that is based on what is best for you and your home, not what is fastest, easiest, or cheapest for a remediation company. After remediation is completed, an IEP can perform post-remediation verification, or clearance testing, to confirm that any microbial growth is gone. 

Unfortunately, because the requirements, qualifications, and skill sets vary greatly among IEPs, it’s important to take time to thoroughly vet any IEP you hire. You cannot assume that because a person is an IEP that they are bound by certain requirements, standards, laws, or operating procedures.  

To help you find a knowledgeable IEP, we highly recommend you visit Step 1 of our "Mold in the Home" feature, watch "Mold Remediation Part 1: Order Of Events & Hiring the Right Team," and download your free copy of "Questions to Ask When Hiring an Indoor Environmental Professional.:

Testing is merely one piece of the puzzle. Unfortunately, there are no perfect tests, nor is there a single test that will tell you everything you need to know about your home. Each test has specific purposes and limitations. Before you or your Indoor Environmental Professional (IEP) run any tests, be clear about what the test can and can’t tell you. Be sure the tests you are running can answer the questions you have about your home and influence your next steps. Testing alone should never be used to determine if a home has a problem. 

Similarly, the tools used by your IEP, such as moisture meters, thermal imaging cameras, particle counters, etc., all have specific strengths and weaknesses. Any testing or tools should be combined with the other elements of a thorough investigation. Sadly, too many professionals “investigate” a home for mold and indoor air quality issues by only taking ambient air samples from the center of various rooms. This approach is flawed for many reasons and is unlikely to provide enough valuable data for the homeowner or renter. It's best to avoid this type of professional and hire someone who will perform a multipronged investigation of your entire home.  

To learn more about testing options for your home, download our free guide, "A Guide to Testing Your Home for Mold & Water Damage" or watch "Testing Your Home for Mold."

To help you find a knowledgeable IEP, we highly recommend you visit Step 1 of our "Mold in the Home" feature, watch "Mold Remediation Part 1: Order Of Events & Hiring the Right Team," and download your free copy of "Questions to Ask When Hiring an Indoor Environmental Professional.:

Mold remediation is not really regulated in the U.S. In fact, it’s a bit like the wild west. Call five different companies and you will receive five possible solutions to your problem. In most states, the person who is remediating your home is not bound by any legal or professional licenses, certifications, or requirements. For example, in the state of Virginia, someone could go to bed one night and wake up the next day and call themselves a mold remediator! That’s why it’s critical for you to thoroughly vet any remediation company before you hire them. This point cannot be stressed enough. Do not hire someone simply because they have a certain certification or good reviews online. It is important to receive the exact scope of the work in writing. At a minimum, we recommend that any remediation project follow the standards laid out by the IICRC S520.

To help you find a knowledgeable remediation company, we highly recommend you visit Step 2 of our "Mold in the Home" feature, watch "Mold Remediation Part 1: Order Of Events & Hiring the Right Team," and download your free copies of "Questions to Ask When Hiring a Remediation Company," "Mold Remediation Contracts," and "Mold Remediation at a Glance."

Buying or renting a home can be an overwhelming process. There is no perfect home, and compromises often have to be made based on each person’s unique situation. We’ve compiled several interviews from various professionals to help you navigate this process.

Additional Resources:

A Realtor’s Perspective: Tips for Buying & Renting a Healthier Home

An IEP’s Perspective Part 1: Tips for Buying & Renting a Healthier Home

An IEP’s Perspective Part 2: Tips for Buying & Renting a Healthier Home 

A Home Inspector’s Perspective: Tips for Buying & Renting a Healthier Home

A Builder’s Perspective: Tips for Buying & Renting a Healthier Home

A Renter’s Survival Guide to Mold

Every day, tens of millions of people just like Aria and AJ are suffering from a wide range of symptoms. They have no idea that their symptoms are being caused or exacerbated by sick buildings and harmful indoor air. While the effects of mold, mycotoxins, and water damage can affect each person differently, even among those living in the same home, exposure to mold and damp indoor spaces  is a major driver of chronic illness, causing more than just asthma and allergy type symptoms.

According to the World Health Organization, “Mycotoxins can cause a variety of adverse health effects and pose a serious health threat to both humans and livestock. The adverse health effects of mycotoxins range from acute poisoning to long-term effects such as immune deficiency and cancer.”

The National Institute of Environmental Health Sciences recent paper states that contact with certain molds may cause allergies, asthma, cognitive issues, mental health issues, immune effects, and even cancer.

In her paper, A Review of the Mechanism of Injury and Treatment Approaches for Illness Resulting from Exposure to Water-Damaged Buildings, Mold, and Mycotoxins, Dr. Janette Hope states,  “It has been estimated that up to 50% of illness results from exposure to indoor air pollution, with exposure to water-damaged indoor environments likely being a significant contributor to this [...] Symptoms and illness due to exposure result from varying mechanisms including infection, toxicity, allergy, irritant effects, and systemic inflammation.”

To learn more about how mold can affect our health from conception to grave, visit our “Research” tab.

Be sure to check out our numerous health-related interviews here.

It's not uncommon to find that people living in the same home are affected differently when exposed to mold and water damage even though they are living in the same space and breathing the same air. Mold-related illness comes with a wide range of symptoms. If and how someone experiences the effects from these unhealthy environments depends on several factors including: genetics, age, nutritional status, pre-existing conditions, individual susceptibility, as well as the dose, duration, and type of mold. Simply put, not everyone will react the same way when exposed to these sick buildings. In a recent interview with Dr. Jill Crista, she summed it up best when she said, “It’s more the rule than the exception that everyone in the same family reacts differently. That’s why it's getting missed.” 

Be sure to check out our numerous health-related interviews here.

Healing your body after exposure to mold, water damage, and poor indoor air quality should always start by prioritizing living and working in a healthier environment. Even then, some may still need to work with a doctor or healthcare practitioner who is familiar with treating those affected by environmentally acquired illnesses. At this time, this often means finding an integrative or functional medicine doctor familiar with treating those impacted by mold and poor indoor air quality. 

You can learn more about how to find a knowledgeable healthcare practitioner here.

Be sure to check out our numerous health-related interviews here.

Change the Air Foundation is dedicated to providing free, reliable, and actionable information. All of our resources can be found by going to our 'Resources" tab.

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