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5 Symptoms Of High Humidity In Your Home

A shocked woman looking at mold on her wall. Find out 5 symptoms of excess moisture in the home.

Are you monitoring humidity levels in your home? Maintaining an ideal humidity range inside your home is more important than you may think. The amount of moisture in the air (humidity) in your home can mean the difference between a healthy home or a home that’s making you sick.

Even without a humidity gauge—known as a hygrometer— to measure the amount of moisture in your air, it can be fairly obvious when you have a humidity issue.

At least, it is if you know what to look for.

5 Symptoms of High Humidity in Your Home

These five issues can be directly tied back to excess humidity or a water leak in your home.

1. Mold

A mold problem in your home always originates from a moisture


Tumore prostatico: la prognosi in base a stadio, grado e rischio

Tumore prostatico: la prognosi in base a stadio, grado e rischio

problem.

Anywhere from 30% to 50% of homes globally have issues with dampness and mold, according to a World Health Organization (WHO) Report on Indoor Air Quality – Dampness and Mold.

Mold spores, which are like microscopic reproductive seeds, are found in the dust and surfaces of every house, including those that don’t have issues with dampness, says WHO.

Mold spores are ubiquitous.

Spores make their way into your home through open windows and doors or by hitching a ride on shoes, clothing, and even pets. And then they wait for the right conditions to thrive.

“Once fungi are indoors,” says the WHO report, “growth can occur only in the presence of moisture.”

Like all living things, mold also needs nutrients to survive. However, your house offers plenty of those in the form of household dust, construction materials, wallpaper, wood, paint, glue, books, and other paper products (to name a few). Modern buildings are made of materials that most molds find delicious, such as drywall, so there’s no shortage of nutrition.

Since removing all fungi food sources from your home is nearly impossible, maintaining ideal humidity levels is critical for preventing mold growth.

2. Insects, Pests, and Arachnids

Spiders, dust mites, and rats, oh my! The second sign of excess moisture and humidity in your home is an increase in uninvited critters and creepy crawlies.

Critters need moisture to survive, and damp homes offer plenty of water for insects, arachnids, and rodents to drink up.

Not to mention the miniature “circle of life” that occurs once mold becomes a food source for small bugs, which then become a food source for larger bugs and spiders, which, in turn, become a food source for rodents, and so on.

Dust mites in particular love to eat mold! (Researchers have found mold spores in their feces and attribute much of the allergenicity to the unique qualities of this lovely combination.)

They’re not the only critters that like to make mold a meal, either.

Booklice (small, soft-bodied insects) usually eat mold, fungi, and glue from book bindings. In homes, booklice are often found in damp areas and are a clear signal that your home has a mold problem.

And then the spiders come along and eat the booklice. And the rodents eat the spiders. It’s like the nursey rhyme, the Old Lady Who Swallowed a Fly.

The longer the moisture problem, the larger the critters, and the more of them you’ll find. Take away the water and they find somewhere else to party. It’s that simple.

3. Respiratory Health Issues

Could respiratory health issues have more to do with poor indoor air quality, due to dampness and mold in your home, than viruses or bacteria? any kind of viral or bacterial infections? Emerging medical research supports this notion.

A pair of studies from the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) and the U.S. Environmental Protection Agency (EPA) estimates that 21 percent of current asthma cases in the U.S. are attributable to dampness and mold exposure.

Of the 21.8 million people reported to have asthma in the U.S., approximately 4.6 million cases are estimated to be attributable to dampness and mold exposure in the home, reports study researchers.

When it comes to predicting asthma, dampness and mold in the home are ranked second only to family history of asthma as a risk factor.

Did you know? Kids who live in a house with a musty “moldy” odor are 2 times more likely to get asthma than kids who don’t. 

How does dampness contribute to asthma?

Researchers suggest that it’s not the excess moisture itself that causes asthma issues, rather, it’s that the moisture influences the growth of various microorganisms that leads to respiratory health issues.

In another study on indoor dampness and asthma, researchers suggest that dampness may lead to the development of asthma, exacerbate existing asthma, and that the factors related to dampness that lead to asthma were most likely attributed to the fungi and dust mite allergens.

The most recent evidence from epidemiologic studies and meta-analyses also show indoor dampness or mold to be consistently associated with increased asthma development and exacerbation, dyspnea, wheeze, cough, respiratory infections, bronchitis, allergic rhinitis, eczema, and upper respiratory tract symptoms—in allergic and nonallergic individuals.

4. Rot and Decay

A building’s longevity is directly connected to its ability to shed water.

In a Building Moisture and Durability report prepared for the U.S. Department of Housing and Urban Development (HUD), moisture is named as the “single greatest threat to the durability and long-term performance” of homes and buildings.

Excessive exposure to moisture is not only a common cause of significant damage to many types of building components and materials, states the report, but it also can lead to unhealthy indoor living environments.

Some of the more serious effects resulting from moisture problems in houses include:

  • decay of wood and corrosion of metals
  • infestation by termites, carpenter ants, and other insects
  • negative impacts on indoor air quality
  • the growth of mold, mildew, and other biological contaminants
  • reduced strength in building materials
  • expansion/contraction damage to materials
  • reduced thermal resistance of wet insulation
  • premature failures of paints and coatings
  • damage to building contents
  • negative effects on building aesthetics

Why is moisture public enemy #1 when it comes to the durability of your home?

Consider the materials used to build a single-family or multi-family residence.

Most building structures begin with a concrete slab foundation that sits in the surrounding soil. Concrete is made from a mixture of crushed stone and a paste made from water and cement. During the drying and curing process, most of the water from inside the concrete works its way out through tiny highways called capillaries. Unfortunately, these tiny moisture highways are two-way streets. Not only can water work its way out of the concrete, but water can also work its way back in via excess humidity, water leaks, and even excess moisture in the soil around the house. (This is known as capillary action.)

It’s like a giant sponge sitting at the base of your home.

Now consider typical building materials that go on top of that concrete slab foundation, such as wood, gypsum wallboard, fluffy insulating materials, carpet, and carpet padding, to name a few. Like concrete, these materials also act like sponges when it comes to moisture, but, unlike concrete, they also do double-duty as nutrient sources for fungi.

This is why we recommend you don’t finish your basement…until you read this.

Fungi cause considerable damage to buildings, according to the WHO Guidelines for Indoor Air Quality.

5. Structural Issues

Not even the dumbest of the three little pigs ventured to make a home out of paper, yet with drywall at the center of our modern construction process, it is much like building houses out of paper maché.

We essentially build ourselves self-composting homes; just add water. The wood we build with is often young wood, and loaded with sap—it’s a tasty treat to wood-eating bugs such as termites and wood-rotting fungi, to name a few.

And, as we covered above, our building materials are prone to rapid degradation when exposed to moisture.

Too much dampness in a building can erode away building materials, corroding metals, decaying timber, softening and crumbling plaster, and disintegrating bricks, stones, tiles, and flooring.

As damp building materials degrade, they release emissions of volatile organic compounds (VOCs)—including formaldehyde—which can lead to increased indoor air pollution and negative health effects for occupants. The use of potentially hazardous chemicals such as pesticides to target termites and pests or chemical biocides meant to “kill” mold can add even more VOCs to the indoor air, and also leave a toxic residue on surfaces, which can become easily airborne and inhaled.

Nasty stuff.

Worse, structural damage from a moisture problem at home most likely isn’t covered by your insurance policy, either. Most homeowners’ policies are designed to cover structural damage that occurs as a result of a specific event (like a hurricane or explosion), NOT from chronic dampness in your home. Damage that happens gradually—like the settling, shrinking, and cracking of your foundation—is typically excluded by homeowners insurance.

Which means you could be left holding the bill for your structural damage caused by dampness, mold, and termites.

Now What?

Now that you know that mold, pests, respiratory illnesses, rot, decay, and structural issues are all signs that you have a moisture problem at home, what comes next? Check out our Complete Guide to Moisture and Humidity in the Home to discover what your ideal household humidity level should be and what steps to take to address the moisture problem for a healthier home.

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What Is The Ideal Humidity Level In A Home?

A humidifier running inside a home. Discover what is the ideal humidity level in a home.

Do you know how humid your home is?

Humidity isn’t an issue reserved only for people living in hot, tropical environments. Even if you live in a cold or dry climate, you could still have household humidity issues to worry about. Too much (or too little) humidity can lead to problems, from mold growth to health issues for occupants.

Discover what the ideal humidity level should be in your home—and why it matters for the health and safety of your family.

What is Humidity?

Before we get into the ideal humidity levels for your home, let’s take a moment to understand better what humidity is and what can impact it in indoor and outdoor environments.

Humidity is the measure of the amount of water vapor in the air.

Remember when you were a kid and learned about the different forms of water? It can be liquid, like the water pouring out of your kitchen sink, solid, like the ice cubes in your freezer, or gaseous, like the water vapor found in the air.

If there is a lot of water vapor in the air, the humidity levels are high.

If you’ve ever been to someplace with high humidity, you’ll recognize the feeling: like you’ve stepped into a steamy shower room and can’t get dry, no matter what. You also likely felt hot and sticky; when the humidity is high, the air gets so clogged with water vapor that there isn’t much room for anything else. Even your sweat can’t evaporate off your body to cool you down because there’s no room in the air for any excess moisture to evaporate off you! You might also notice that cool surfaces, like cold water pipes and tile floors, are damp due to condensation.

If there is minimal water vapor in the air, the humidity levels are low.

If you’ve ever been someplace cold and dry, you’ll know how too little humidity feels. Without enough moisture in the air, your skin and mucous membranes dry out and feel chapped, cracked, and uncomfortable. Too little moisture in the air can also impact immune health, which we’ll learn more about in a minute.

When talking about humidity, what we usually reference is relative humidity or RH, or how much moisture is in the air compared to the maximum amount of moisture that can be contained in the air at a certain temperature. This is expressed as a percentage, as in 50% humidity, or 50% RH.

Another measurement of humidity is called absolute humidity. This represents the weight ratio of vaporized water to 1 kg of dry (moisture-free) air. This measurement is expressed as kg/kg, as in 0.008 kg/kg. This is mostly the measure used by nerds like us who study these things.

When we are measuring humidity levels and discussing the ideal humidity levels in a home, relative humidity is more commonly used.

So let’s focus on relative humidity and the percentages that make up a healthy, comfortable home!

What Impacts Humidity Levels?

Temperature is one of the more prominent factors when it comes to influencing humidity levels.

  • As temperatures rise, the amount of moisture the air can hold increases.
  • As temperatures drop, the amount of moisture the air can hold decreases.

Imagine a sponge. As the temperatures increase, that sponge gets larger and can absorb more water (or water vapor, to be more precise). But as the temperatures drop, that sponge gets squeezed smaller and tighter, resulting in less room for water.

Temperature isn’t the only factor that impacts humidity levels, either.

Your everyday household activities can release more water vapor into the air, such as:

  • cooking
  • showering/ bathing
  • watering plants
  • hanging laundry to dry inside the home

Plus, spills and water leaks can also release more water vapor into your home.

Even something as simple as opening a window can impact indoor humidity levels by letting in more water vapor from outside.

If your indoor air becomes too humid, it can result in a myriad of issues, including these five symptoms of excess humidity in the home.

What is the Ideal Humidity Level in a Home?

So what is the ideal humidity level for optimal comfort, health, and safety?

According to ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers), the ideal indoor humidity range is between 40% and 60%.

Dry indoor air (between 0-40%) becomes a physical health hazard. It can impair the respiratory immune system defenses, allowing viruses to infect us more easily. Plus, evaporation of moisture leads to airborne viruses that can float through the air easier and survive longer, which increases our chance of catching viral illnesses.

Overly-moist indoor air (from 60% to 100%) can also feel uncomfortable to our bodies. But the big concern of overly humid air comes as it creates a water-rich environment for unfriendly organisms to grow and thrive. Mold is just one example of an organism that needs moisture to grow and spread. Another is dust mites, which thrive in humid environments. Between 40% and 50% humidity is ideal for controlling dust mites. Above 50% humidity and dust mites can go from bothersome to out of control.

“Relative humidity of 40-60% in buildings will reduce respiratory infections and save lives,” says Dr. Stephanie Taylor, Infection Control Consultant at Harvard Medical School.

Want to learn more about how moisture can impact the health and safety of your home and what tools can best help you measure, monitor, and control your humidity levels? Check out our Complete Guide to Humidity and Moisture in the Home.