Do dehumidifiers help with allergies?

Dehumidifiers can help improve air quality at home, but do dehumidifiers help with allergies? We do know that reducing humidity in our homes can significantly protect our health, including reducing asthma symptoms and irritation. It's also been observed that dehumidifiers help with snoring.

Dehumidifiers achieve this by ensuring humidity levels remain healthy, stopping the spread of dust mites, mold, and more. In this article, we explore whether dehumidifiers help with allergies, and if they help to make a home happier and healthier for sufferers.

You'll also find plenty of other helpful articles on dehumidifiers here at Live Science, including Do basements need a dehumidifier? and how to clean a dehumidifier. You can also check out some of our top rated models in our guide to the best dehumidifiers. 

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Do dehumidifiers help with allergies?

The quality of the air we’re breathing is getting worse, scientists have warned. "The rate at which indoor air is exchanged for fresh air is now 10 times lower than it was 30 years ago," warned scientists in the BMJ in 1998. This leads to increases in humidity that are harmful to our health, particularly for those with allergies and chronic conditions such as asthma.

So do dehumidifiers help with allergies? Yes, and here’s how.

Dehumidifiers work by removing excessive moisture from the air and ensuring relative humidity remains at a stable level. The EPA advises that an optimum level for relative humidity is between 35-50%. At this point, they inhibit the growth of dust mites, a microscopic organism responsible for the majority of allergic reactions.

Dehumidifiers fitted with a high-quality HEPA filter or a filter with an anti-bacterial coating can impact seasonal allergies­­ (Urologic Nursing) caused by exposure to irritants, such as grasses and especially pollen in the air. As the air is drawn through the dehumidifier, particles are captured in the filter, purifying the air. As well as pollen, some dehumidifiers are also fitted with pet hair filters that can reduce – but not remove – the presence of pet hair in the environment, reducing allergies and irritation.

Do dehumidifiers help with dust mites?

Dust mites are the biggest cause of indoor allergies, scientists have found (the BMJ). Dogs and cats fill out the top three places. Populations of microscopic dust mites proliferate in humid environments and can lead to the tell-tale signs of an allergic reaction to dust mites, according to the Asthma and Allergy Foundation of America (AAFA), including a stuffy nose, itchy eyes or skin, or wheezing and coughing.

Dust mites grow best at high humidity levels, says the AAFA. So think your cooler home is safe? Think again. A 2003 PubMed survey of US homes found that "most US homes have detectable levels of dust mite allergen". A UK PubMed study found similar levels of infestation, noting that "factors such as older homes, carpets, and mattresses, damp and condensation are associated with higher mite allergen".

By stabilizing relative humidity at an optimum level of under 50%, dehumidifiers play a crucial role in reducing dust mite infection, PubMed research has established. The impact is massive, with researchers noting allergen levels were ten times lower in homes that used a dehumidifier.

If you have children, a dehumidifier could help reduce the risk of them developing a range of conditions, such as asthma, allergic rhinitis, atopic dermatitis, and abnormal lung functions, one World Allergy Organization Journal study found.

Do dehumidifiers help with asthma?

Dust mites are the main trigger for asthma, says the American Lung Association. So reducing them is, understandably, one of the main priorities, says the Nursing Clinics of North America.

The evidence is clear that dehumidifiers can reduce the risk of dust mite infection in your home, making the air better to breathe for those with asthma, but that’s not their only benefit.

High humidity can affect asthmatics in several ways, Healthline warns, causing trouble breathing or shortness of breath, coughing, tightness in the chest, and wheezing. These can cause your body temperature to increase, which can lead to dangerous symptoms such as dehydration. Together, this could lead to potentially hazardous asthma attacks, according to the AAFA. Dehumidifiers remove excess moisture from the air making breathing easier for everyone. Left on all night, they can also help improve sleep (whether you have asthma or not!).

Excessive moisture can also encourage mold growth, which can generate an allergic reaction and cause asthma attacks, says the NHS. Children are particularly susceptible to mold, with one PubMed study finding that children in moldy homes are three times more likely to develop asthma by the age of seven than others.

Mold can grow anywhere the humidity level exceeds 60%, says the EPA. So it’s important to limit moisture in the home, with a dehumidifier providing the first line of protection.

As well as dust mites and mold, humidity and air pollution are closely linked, says the AAFA. Whether you call it smog, ozone, or air pollution, a dehumidifier – specifically one fitted with a HEPA – can improve indoor conditions.

• Related: Does a dehumidifier cool a room?

Do dehumidifiers help with eczema?

Excessive sweating caused by high health and humidity can aggravate eczema, making skin feel itchy. So, do dehumidifiers help with eczema? Yes, but only in certain circumstances.

A dehumidifier can reduce moisture, making the indoor environment feel more comfortable. According to Everyday Health, less moisture means less irritation. To have the maximum impact, you should operate your dehumidifier alongside an air conditioning system to reduce the temperature and humidity.

Those with eczema can find that dry air with low humidity can make symptoms feel worse, according to the National Eczema Association. The problem can be exacerbated in winter, as we turn on heating systems, we dry out the air even further. In these situations, a dehumidifier could actually make things worse by removing further moisture from the air. If you suffer from eczema and recognize this as a trigger, consider investing in a humidifier to provide additional moisture to the air when it’s needed.