Does Your Crawl Space Affect The Air Quality In Your Home?

Does Your Crawl Space Affect The Air Quality In Your Home? - Image 1

When you think about air pollution, what typically comes to mind?

cows chatting

It's true. Cows generate 15% of global greenhouse gas emissions every year.

Vehicle emissions? Manufacturing plants? Cow farts, even?

Well, you're not far off the mark. Those factors do in fact contribute to air pollution, but have you ever considered what causes indoor air pollution?

You should be concerned about your indoor air quality, and if you've stumbled upon this blog, there's a high chance you have a crawl space (we might have a knack for understanding Google keywords, or maybe we're just a little psychic – who's to say?).

Here's the deal. Approximately 60% of the air in your home originates from the crawl space, and according to the United States Environmental Protection Agency (EPA), the average American spends around 90% of their time indoors.

While I'm no mathematician (actually, I'm a writer specializing in air quality – hi nice to meet you), it's clear that those stats point to the obvious: it's crucial to maintain good air quality in your crawl space for the well-being of your home. 

As experts in foundation and crawl space repair, we get asked a lot of questions about crawl spaces, indoor air quality, and everything in between. So we put this blog together to answer your most burning questions. We'll dive into the impact of indoor air quality on your health, how your crawl space air moves through your home, how to identify bad air quality, and how to know if it's coming from the crawl space. Let's dive right in.

What is air quality and how does it affect you?

Before we get into the nitty-gritty, let's first define the basics so we're all on the same page. 

Indoor air quality defined

Indoor air quality (IAQ, for short) refers to the condition of the air inside enclosed spaces, such as homes, workplaces, and public buildings, including the presence of various pollutants and allergens.

Dust in the air

Particulate matter often looks like this. Dust dancing in the air right after you lift up your favorite blanket.

Your indoor air can be polluted with a wide variety of substances including:

  1. Particulate matter: These microscopic particles float in the air and come from things like dust, pet dander, and cooking.
  2. Volatile organic compounds (VOCs): Organic chemicals that vaporize into the air, often released by common household products like paints, cleaning supplies, and building materials. 
  3. Mold and mildew: Microorganisms that live in damp environments (like that crawl space of yours) and release airborne spores, that when breathed in can cause respiratory issues. 
  4. Carbon monoxide (CO): A colorless, odorless gas produced whenever fuel burns, which can be deadly in high concentrations. 
  5. Radon gas: A naturally occurring, radioactive gas that comes from the natural decay of uranium in soil. It often seeps into buildings and can increase the risk of lung cancer.

Okay, now that we know what indoor air quality is, let's discuss how these pollutants affect your health if you breathe them in for an extended period of time. 

How does indoor air quality impact your health?

The quality of the air we breathe has a huge impact on our health. Here's the thing, though. If you breathe these pollutants in once, you're fine. Even twice, you're good. Thrice (Is that a thing)? Don't sweat it. But if these pollutants are in your home, they're coming from somewhere and most likely won't go away on their own, which means you are continuously breathing in bad air. And that's what affects your health.

Poor indoor air quality is linked to a range of health problems, including:

  • Respiratory issues.

  • Headaches and fatigue.

  • Skin irritations.

  • Long-term health risks, including heart disease and lung cancer.

Stack effect rendering with crawl space

This is the stack effect, a process in which hot, humid air leaves the home through your attic, and new air is pulled upwards through the crawl space. If your crawl space air is filled with musty odors and allergens such as mold spores, dust mite waste, animal dander, and others, these elements will enter your living space and affect your quality of life.

How does the crawl space affect indoor air quality?

Now that we are all on the same page about IAQ, let's talk about your crawl space. The crawl space is not a hot spot to hang out in, but it is a hot spot for your overall indoor air quality.

There are a few ways the crawl space influences the air you breathe, including: 

1. Air exchange and ventilation.

One of the primary ways crawl spaces affect indoor air quality is through air exchange and ventilation. Crawl spaces are often connected to the rest of the house through several openings and vents. This connection allows air to flow between the crawl space and the living areas. If the crawl space air is contaminated with mold spores, dust, or radon gas, these pollutants can be drawn into your home through the ventilation system. 

2. Moisture and humidity 

Crawl spaces are often damp due to the exposed dirt floor. This damp dirt releases moisture into the air, which moves upward through your home, making it more humid. This excess moisture and humidity can lead to mold and mildew growth, releasing spores that can trigger allergies and respiratory issues in your home.

Crawl space with dirt floor

Additionally, high humidity in the crawl space creates a thriving environment for dust mites and pests, which can introduce even more allergens and pollutants into your home.

3. Insulation and air sealing

Unfortunately, crawl spaces often lack proper insulation and are typically separated from the conditioned living space. This contributes to significant temperature fluctuations in the crawl space, allowing moisture and external air to infiltrate the home. 

When warm, humid air enters a cool crawl space, condensation forms. This excess moisture creates an environment for mold and mildew to grow. As these microorganisms live in your crawl space, they release spores into the air, which can move upward into your home.

Temperature fluctuations in a poorly insulated crawl space affect the airflow and ventilation. During extreme temperatures, this change in ventilation can impact the distribution of contaminants and pollutants in your home. 

How do you know if you have poor indoor air quality?

There are a few ways to figure out if your home has poor indoor air quality and the good news is, you can determine it yourself without having to call an expert. 


Set the hygrometer in a common area for at least 24 hours. Try to avoid setting it in bathrooms or kitchens as the humidity tends to fluctuate when you cook or shower.

  1. The sniff test: If your home smells musty, mildewy, or anything of that nature, it's safe to say you have an issue.
  2. Hygrometer: A hygrometer is a tool that measures the amount of humidity in the air. They're inexpensive and easy to use. Just place it in a room in your house, like a living room or bedroom (try to avoid kitchens or bathrooms, as the moisture levels in the air can fluctuate in those areas). If the levels come back high, then you know you have an air quality issue. 
  3. Radon test kits or radon monitor: This inexpensive tool will test the radon levels in your house and indicate if your home has high radon levels.



How to improve your home's indoor air quality

If you suspect that your indoor air quality at home is not good, there are a few different ways to fix this issue.

  • Air filtration. The first step is to make sure you have good air filtration. Some airborne compounds, like radon, are incredibly small and can easily pass through traditional filters. Consider an air filter specifically designed to handle smaller compounds. 
  • Crawl space encapsulation. The best thing you can do for your crawl space is to encapsulate it (and no, we're not just saying that because we're a crawl space company). Crawl space encapsulation is the process of sealing the crawl space from the outside. It involves installing thick, overlapping sheets of polyethylene plastic on the crawl space walls and exposed dirt floors. It reduces humidity, prevents leaks, pest infestations, and mold.

crawl space and indoor air quality - Image 6

  • Dehumidifier. A dehumidifier is designed to remove excess moisture from the air. It draws in air from the crawl space, passing it over a cooling coil, and condensing the moisture into water. The collected water is then typically pumped out of the crawl space to an exterior drainage area. This, in turn, reduces mold and mildew growth, minimizing allergen exposure, and lowering humidity levels in your crawl space (and thus, your entire home).
  • Depressurization. When it comes to reducing radon levels in your home, depressurization is the best solution. This method involves creating a pathway for radon gas to exit your home safely and ensure it's vented outside. These systems are designed to maintain a lower air pressure beneath the foundation compared to indoors, preventing radon gas from entering living spaces. Make sure to use a professional radon mitigation contractor for this type of work, though. They will be able to assess the specific conditions of your home and determine the most suitable depressurization method for your situation.

The most important thing to do now is to take action

If you're noticing signs of poor indoor air quality, and you think it's coming from your crawl space, it's time to take action. Ignoring these issues won't lead to them going away (no matter how much you want that), and instead, will only make them get worse. Here at Thrasher, we offer services to improve indoor air quality, including crawl space encapsulation and dehumidifier installation.

If you are in our service area and would like to chat about your indoor air quality, our team at Thrasher Foundation Repair is here to help. Contact us today by starting a chat in the bottom right corner, filling out this form, or calling us at 1-844-948-3306

Now that you know about how crawl spaces affects your indoor air quality, don't you wanna know everything there is to know about crawl space encapsulation? We thought so... check out, "What is crawl space encapsulation? Everything you need to know."

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