Excess indoor humidity can make life miserable. People who suffer through humid air in their homes can experience a wide range of problems—anything from frizzy hair, to sleeplessness, to respiratory system illnesses. There are many potential causes for indoor humidity, but they can be remedied rather simply. You can, and should, gain control over the humidity level in your home. Doing so could save you and your family from any number of adverse reactions caused by unwanted moisture in the air.
The first step in effectively combating any recurring problem is to determine the underlying cause. What is humidity in the first place, and why is it in your home? In the most general sense, humidity is the presence of water vapor in the air. Water vapor enters the Earth’s air, or atmosphere, in two main ways: 1) heat from the sun evaporates water from oceans, lakes, and ice, and 2) plants sweat water out in the process of transpiration. Water vapor usually doesn’t stay in the atmosphere very long. It accumulates and then returns to the Earth as precipitation.
Humidity can get inside your home in a number of ways. Typically there exists a certain level of moisture in the air that enters a home from the outdoor environment. This level can vary according to regional weather patterns. Your home also contains several areas where water vapor is produced. In the kitchen, steam can be issued from cooking, running the dishwasher, and using hot water in the sink. Showers, laundry machines, damp basements, and even some aquariums can raise the humidity level inside a home. Indoor gardening and the water in house plants can also contribute to moisture in the air. Indoor swimming pools, hot tubs, and saunas, as well as actual humidifiers, will make the air in your home more humid. Newer homes, with more modern construction techniques that prevent air drafts and water intrusion, can sometimes trap moist air inside.
How much of the air is water vapor? Outdoors, near the surface of the Earth, water vapor makes up very little actual mass, anywhere between 1%-4% of the total volume of matter in the air. The rest is mostly nitrogen and oxygen, with trace amounts of about a dozen other gasses. However, the humidity percentage we are most familiar with, the one used by weather reports, is a statistic referred to as “relative humidity.” Relative humidity is the percentage of water vapor compared to how much the air will hold before it condenses (in rain or fog). So, at 0% humidity the air is completely devoid of water vapor and at 100% the air is totally saturated. A 25% humidity level will feel like Las Vegas, Nevada in the middle of the summer, whereas 90% humidity will feel like the Brazilian rainforest during the monsoon season.
Now that we know what humidity is and how it’s measured, we can discuss the implications of high humidity in indoor environments. The U.S. Environmental Protection Agency recommends that, for human health and comfort, humidity levels should be between 30% and 60%. Low humidity levels can lead to dry, irritated skin and a feeling of thirst. High humidity levels can lead to even more adverse health effects. On the less hazardous end of the spectrum, human hair can dry out, twist, and tangle when it soaks up the water vapor. Also, high humidity can lead to a general feeling of discomfort. This is because high humidity disrupts one of the main ways your body regulates its temperature: sweat. When you’re too hot, your body secretes water on the skin’s surface. The water cools in the breeze and lowers the temperature of your skin. But when the humidity level is close enough to the condensation point, sweating loses its cooling effect. When experienced for an extended period of time, this uncomfortable feeling can lead to sleep disruption, anxiety, fever, light-headedness, dehydration, and exhaustion.
High humidity can affect the respiratory system in several ways. First, unusually high humidity makes the air denser or heavier, thus forcing the lungs to work harder to get the same amount of oxygen from breathing. Also, dust mites multiply much faster in humid climates. Dust mite populations thrive in relative humidity levels of about 75% – 80%, but decrease significantly in conditions below 50%. Although dust mites need water to live, they don’t actually drink water. They absorb it from the air. When they air is too dry, they die of thirst. Additionally, moisture can cause rotting in building materials, which in turn attracts pests. Bugs can damage the structural integrity of your home, and the waste they leave can produce allergens in the air, triggering asthma attacks and allergic reactions.
Humidity can also intensify allergens and other pollutants in the air, especially mold spores. While it is true that rain will oftentimes clean the air of allergens , humidity that doesn’t condense can help keep allergy-inducing pollen and dust in the air. Since mold grows quickly in moisture-rich environments, overly humid homes are susceptible to mold growth. Mold and mildew release tiny particles, called spores, into the air, which can cause allergies when inhaled. Exposure to mold can cause any number of reactions, the most common of which include flu-like symptoms: irritated eyes, headaches, sneezing, coughing, wheezing, sinus pressure, drowsiness, and fever. Certain kinds of molds, such as the “toxic black mold,” Stachybotrys, have also been linked to more adverse, long-term health problems. Exaggerated allergic reactions, bleeding in the lungs, and dizziness can result from black mold exposure, especially in young children, the elderly, and people with weakened immune systems.
What can you do when you suspect that high humidity in your home is causing breathing problems or other health concerns? How can you control and lower your indoor humidity? Here are three ways to make sure that humidity in your home does not lead to health problems for you and your family:
- Prevent humidity from indoor sources—washing machines, dryers, showers—by properly ventilating areas where water vapor is likely to accumulate. Open windows, turn on any exhaust fans, and leave doors throughout the home open for proper air circulation. Especially in areas of the country where the outside conditions are relatively dry, humidity control can be as simple as letting in some fresh air through an open window.
- If the low-tech solutions of opening windows and turning on vents are out of the question, consider using air conditioners, heaters, or dehumidifiers to regulate moisture in your home. If you have an existing air conditioning or heating system in your home, you can retrofit it with de-humidifiers. You can use a humidity detector, or hygrometer, to verify how humid your home is. Somewhere near 50% relative humidity is ideal. If it’s above 65%, you may need to take steps towards dehumidification.
- If it’s too late to prevent humidity problems, and you suspect that indoor moisture has caused rot, mold, mildew, dust, or allergens, you can hire an indoor environmental professional to test the air quality of your home. This kind of service will provide analysis from a digital moisture reader, which will locate the areas of your home that may be causing excess humidity. Certain tests can also determine if dangerous mold spores are present in your home’s air.
Indoor humidity can come from a variety of sources, and moisture can become trapped easily, especially in newer homes. When high humidity levels threaten your health and safety, you need to take steps to combat the problem. When left unchecked, moisture in your home can lead to breathing trouble, dust mites, mold, rot, and pest infestations. Properly addressing a humidity issue could be as simple as opening your windows and turning on your heater. If the problem progresses, you may need to call in the pros to make certain indoor humidity isn’t going to be drenching you in medical bills and home repair costs.