Does a Dehumidifier Help With Allergies?

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If you suffer allergy symptoms even while locked inside, there are options for finding relief. One of the best, surprisingly, is using a dehumidifier.

Yes, dehumidifiers do help with allergies. These practical home appliances help reduce the overall humidity inside your house. This not only makes the air feel more comfortable, but it actively reduces the activity of many common allergens found in the home, including the most likely culprit behind your sniffing and sneezing.

Keep reading to find out how a dehumidifier helps with allergies and the best ways to put these appliances to use.

person sitting next to a dehumidifier

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How a Dehumidifier Helps Fight Allergies and Asthma

diagram showing how a refrigerant dehumidifier works

Before you can understand how a dehumidifier works to reduce allergy symptoms, you first need to understand how a dehumidifier works.

By pulling air from your home into the machine and over cold metal tubing, a dehumidifier turns moisture in the air into liquid water. This water runs down the tubing into a collection reservoir or through a drain. The air that leaves the unit is drier than when it came in, effectively reducing the overall humidity in your home.

This process helps make the air feel more comfortable but can also impact the number of certain allergens floating in the air and thriving in your home. More specifically, reducing humidity can combat mold, mildew, and dust mite activity.

Helps Prevent Mold Growth

Mold requires a moist surface to grow. When the humidity in the air collects on drywall, grout, and other porous surfaces, it provides the perfect habitat for mold to thrive. Once mold has established, it will release spores into the air in an attempt to spread.

It’s these spores that trigger allergy symptoms. According to the Mayo Clinic, sneezing, coughing, running nose, and itchy eyes are the most common symptoms of a mold allergy.

If you suffer from a mold allergy or have obvious mold growth in your home, you can use a dehumidifier to help relieve the problem. By keeping relative humidity levels below 60%, you can greatly reduce mold activity. Consistent levels closer to 30% will kill mold and keep it from releasing spores altogether.

Reduces Mildew Growth

a dehumidifier next to a window with mildew

The term mildew refers to specific types of fungi that tend to grow on flat, very moist surfaces. Like other kinds of mold, mildew releases spores that can cause allergy symptoms in sensitive individuals. 

Note: Unlike mold, mildew does not penetrate the surface it grows on. This characteristic makes it easier to eradicate and less likely to spread without you noticing.

Mildew tends to grow in areas that are frequently exposed to high humidity, such as in the bathroom and on window sills. Symptoms of a mildew allergy are similar to that of mold allergies.

If you have a mildew allergy, then running a dehumidifier in your bathroom or in rooms that suffer condensation on the windows can make a huge difference in controlling mildew growth.

Keeps Dust Mites Under Control

Dust mites are one of the most common causes of indoor allergies. These microscopic pests feed on shed dead skin cells and commonly live in bedding and upholstery. People who are allergic to dust mites react to the proteins in the air that come from dust mite urine and feces.

Dust mites thrive in humid conditions. They are most active when humidity is above 70%, according to the Allergy and Asthma Foundation. When your indoor humidity level is below 50%, you can greatly decrease dust mite activity, which means fewer allergens in the air.

According to the American Lung Association, people sensitive to dust mites show symptoms such as runny nose, sneezing, watery eyes, and asthma attacks.

If you’re allergic to dust mites or have asthma, it is worth using a whole-house dehumidifier to keep levels below 50%. Or, at the very least, utilizing a bedroom humidifier to make your sleeping area less habitable for dust mites.

How to Use a Dehumidifier for Allergy Relief

There are many different ways to utilize a dehumidifier to fight allergies. If you are unfamiliar with these devices, start by reading our article on how to use a dehumidifier for some general pointers.

To keep allergens at bay, you’ll want to target your living spaces, pay special attention to humidity levels after floods or leaks, and keep humidity under control in your basement and crawlspace.

Dehumidify Your Living Spaces

a woman turning on a dehumidifier in the living room

In terms of comfort, the ideal relative humidity level inside your home is between 40% and 50%. If you want to combat mold and dust mites, you should keep the humidity level closer to 35%.

If your home is consistently hitting above this mark, it is worth investing in a large portable dehumidifier or a whole-house dehumidifier. By getting a dehumidifier rated for the size of your entire house, you can help reduce allergen activity in every room, including bathrooms, bedrooms, and living spaces.

If a unit this size is outside your budget, getting one or two smaller units can also work. Place these units in areas with the worst humidity problem, such as the bathroom. Or, to combat dust mites specifically, place the unit in your bedroom.

Note: It is important to take some time to measure the humidity levels in different areas of your house throughout the day before deciding what unit to get or where to place it. For this, you’ll need a quality hygrometer. With this tool, you may find that some rooms suffer from higher humidity than others.

You may also find that humidity is not, in fact, a problem in your home. If your humidity levels frequently fall below 35%, the cause of your stuffiness and respiratory issues might actually be from excessively dry air. In this case, you may consider investing in a humidifier.

After Leaks and Floods

mold growth after flooding

Water leaks and floods can instantly turn a low humidity home into an overly humid home. Not only does that spell disaster for your allergies, but it can also cause a lot of issues for your house.

Pooling water on the floor is quickly wicked up by drywall and wood framework. This creates the perfect environment for mold to grow. And, because much of the moisture from the leak will evaporate into the air, that mold can easily spread to other areas of your home.

By using a dehumidifier after the water from the leak or flood is cleaned up, you can help remove this excess moisture from the air. The dehumidifier will also help pull water from surfaces, thereby preventing mold from establishing in the first place.

If you’ve recently suffered water damage, don’t wait. Get a quality dehumidifier running in your home right away. Doing so can prevent months of aggravated allergies.

In Your Basement and Crawlspace

Homeowners often overlook the basement and crawlspace when trying to tackle humidity. These rooms are in direct contact with the soil, which is usually wetter than the outside air. So, they tend to be more humid than the rest of the house. 

The moisture in your basement and crawlspace rises and saturates the rest of your home. When you tackle the source of the humidity, you can avoid introducing this excess moisture into your living spaces. This means less chance for allergens to establish.

Basement dehumidifiers should be rated for large spaces and powerful enough to tackle consistent high humidity levels. Even units for crawl spaces should carry a higher room rating because they’ll need to run more or less constantly to counteract the moisture being introduced by the soil.

Find Relief With a Dehumidifier

Dehumidifiers are an often overlooked tool in fighting allergies. These powerful appliances don’t purify the air of allergens. Instead, they reduce humidity levels to make your home less hospitable to mold, mildew, and dust mites.

By reducing the activity of these common allergens, you can breathe easier and feel more comfortable inside your home.

Have more questions on dehumidifiers and their role in reducing allergy and asthma symptoms? Leave a comment below!

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Aaron is the founder of and Essential Home and Garden. With over 15 years of hands-on experience in home ownership, lawn care, and gardening, Aaron is a seasoned expert in areas like lawn care, DIY, HVAC, and pest control.

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