Find A DoctorDust mites and humidity
Humidity is one of the most important factors affecting dust mite populations. Dust mites absorb moisture from the air to stay hydrated. Without it they die. That’s why you won’t usually find them as much, causing allergies, in places with low humidity such as deserts and at high altitudes.
Studies show that house dust mites tend to prefer living in bedrooms over other areas of the home. This is partly due to the abundant food supply – dust mites feed on dead skin cells. But also because the humidity conditions are just right, especially as beds are warm and moist.
Read on to learn more about the relationship between dust mites, humidity and allergy symptoms.
What is humidity?
Humidity is the amount of moisture (water vapor) in the air. It varies depending on the season, weather and your location. Generally, humidity levels are higher in summer and lower in winter.
Even your breathing can contribute to humidity in the home. The human body is nearly 70% water and the air in our lungs is almost completely saturated with water vapor. This vapor is the same temperature as the body (98.6°F).
In winter you might see your breath, or the water vapor in it, when it’s cold outside. But your breath always contains this moisture, you just don’t see it. We constantly breathe out moisture as we move about our homes or sleep at night.
Absolute vs relative humidity
You may come across both phrases on weather websites and apps. But with regards to allergies and dust mite control, we’re most interested in relative humidity.
What are seasonal allergies?
Absolute humidity is a measure of the actual amount of moisture in the air, regardless of air temperature. The higher the amount of moisture, the higher the absolute humidity.
Relative humidity is a measure of the amount of moisture in the air compared with the total amount that can exist in the air at its current temperature. Warm air can contain more moisture than cold air.
What level of humidity do dust mites thrive at?
Dust mites like it tropical. They love relative humidity levels of around 70–80%. Anything below 50% isn’t enough and they’ll gradually dry out and die. Temperature wise, 68–77°F degrees is the perfect range for growth and reproduction. When it gets too hot for them, they die (we’ll look at this later). When it’s too cold they slow down and become inactive.
Humidity risk factors
Humidity problems at home are caused by excess moisture in the air. Let's look at what could be causing this moisture.
Everyday living activities
Activities such as cooking and showering creates condensation on surfaces – in addition to indoor clothes drying, which also puts moisture into the air. Over time, these activities can lead to higher humidity levels. That could mean an increased risk of exposure to allergenic mold spores as well as dust mites and their waste.
Building moisture
If you live in a new build property or have recently finished a big renovation project, your home may still be drying out. The process of mixing up concrete, screed and plaster uses lots of water, which creates indoor moisture – though much of it eventually escapes directly to the outdoor air. Rainwater can also damage parts of your roof and gutters, causing leaks.
Dust mites can make you sneeze…but do they bite?
What are the effects of dust mites and humidity on health?
High relative humidity indoors attracts dust mites. And the more dust mites in your home, the more dust mite waste or allergens. That can increase the risk of people developing dust mite allergies and lower respiratory symptoms.
Generally, a dust mite allergen may cause the following symptoms:
- Congested, stuffy nose
- Runny nose
- Sneezing
- Itchy nose
- Postnasal drip (the feeling of mucus moving down the back of your throat)
- Itchy, red or watery eyes
- Coughing
- Tight chest or wheezing
- Sinus inflammation and/or pain
- Skin reactions including eczema
You can read more about dust mite allergy signs and symptoms here.
Does a dehumidifier get rid of dust mites?
A dehumidifier can help kill dust mites by creating an unfriendly environment for them. Dust mite numbers are minimized when the relative humidity is below 50% and they peak at 80%.
Keep in mind, the size of an indoor dust mite population is directly dependent on relative humidity, which is affected by the climate in your home or the part of the world you live. In fact, different dust mite species thrive in slightly different environments depending on the temperature.
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Dehumidifier maintenance
Follow these tips to improve the performance of your dehumidifier:
- Set the relative humidity level between 30–50%
- Pick the best spot – make sure there is free space all around the unit
- Close all windows and doors – enclosing the space maximizes its efficiency
- Regularly change the water – left to stagnate in the tank, it can become contaminated
- Keep the filter clean to allow air to flow through it
What happens if my home is too humid and becomes damp?
The environment may become very welcoming for dust mites. And dirty reservoirs and filters may expel mold spores and bacteria into the air. This could worsen allergies or lower respiratory symptoms.
You can measure the humidity in your home with a hygrometer. They look a bit like a thermometer and measure the amount of moisture in the air.
What temperature gets rid of dust mites?
Dust mites are sensitive to heat. To get rid of the bugs and wash away allergens, change your bed linen at least once a week and use the hot cycle on your machine (120°F - 130°F).
Drapes and curtains can be dry cleaned, or you can use a carpet steam cleaner to help keep dust mite populations low. But ideally, consider replacing all carpets with hard wood flooring.
Read more tips you can follow to get rid of dust mite allergens here.
Summary
Humidity is one of the most important factors for determining how many dust mites live in your home, as dust mite populations thrive at 70–80% humidity. Cooking, showering and indoor clothes drying can all increase humidity levels. You can monitor humidity levels in your home using a hygrometer and reduce them with a dehumidifier. It can help reduce dust mite allergy symptoms.
Last medically reviewed on 27/11/2022