Beyond comfort, humidity can seriously impact the health of your home and its inhabitants.
Everyone has experienced the fatigue-inducing combination of high temperatures and high humidity outside, but the humidity indoors often escapes our notice. Though humidity in the home typically is not as noticeable as outdoor humidity, long term chronic exposure to unhealthy levels of air moisture (or lack thereof) can have a surprisingly large effect on the health of inhabitants as well as the home itself. The Environmental Protection Agency lists indoor air quality as a top environmental health threat, yet many are unaware of the quality of air inside the home.
Excessive indoor humidity leads to persistent dampness, which can, in turn, encourage the formation of dust mites and mould. A concentration of mould and dust has the potential to not only exacerbate any existing respiratory problems but has also been directly linked to the development of conditions such as COPD and asthma in otherwise healthy individuals, and can worsen allergies. Overly dry air can be just as harmful to your health, as it dries out the upper respiratory system and greatly increases the body’s susceptibility to airborne infection, hence why you are more likely to catch a cold or flu during the winter.
Ideally, relative humidity levels in the home should be higher than 30% during colder, dry months, and between 40–60% during the summer. Microorganisms typically require a relative humidity exceeding 60% in order to grow and spread throughout the home, though they can remain dormant indefinitely in drier conditions. humidity, though they can remain dormant is unable to grow in this environment, and usually requires a relative humidity higher than 60% to flourish and spread. Most people will feel comfortable with humidity between 35–50%, but this number may be slightly higher for infants and the elderly. is the range at which most people tend to be comfortable, but this number can change slightly for babies and the elderly, who require slightly moister air.
While the relative humidity inside is related to moisture in the outside air, many day-to-day activities from showering to boiling water on the stove release moisture into the air inside, and without proper ventilation to allow this moisture to escape, humidity can increase to an unhealthy level quite quickly.
Many issues with dampness in the home have been linked to building practices popularised by the post-war housing boom, and the global oil shortage of the 1970s. The economic boom of the 50s resulted in an unprecedented demand for housing, and in an effort to meet this demand, builders moved away from traditional brick, mortar and plaster in favour of inexpensive, more easily-installed drywall. Ironically drywall is incredibly difficult to dry once exposed to moisture, and the cellulose found inside the material makes it an ideal incubator for black mould growth.
Two decades on, the global oil shortage of the 1970s resulted in the first push for constructing energy-efficient homes. In an effort to reduce energy expenditures related to heating and cooling, homes built in this era were insulated so thoroughly that they are almost hermetically sealed to the outside air. Unfortunately, this had the corresponding effect of trapping damp air in homes with no ventilation to allow moisture to escape. Homes constructed from the 1970s onward have been known to have particular issues with mould growth and persistent dampness, particularly as these homes age.
Homes with crawl spaces or basements are also particularly susceptible to high humidity. These areas are naturally humid as they draw moisture from the ground which then seeps through the foundation, floors, and walls and spreads through the rest of the home. 40% of inside air originates in the crawl space, so remedying dampness here can seriously improve air quality throughout the rest of your home.
For an environmental factor that is so often overlooked, the quality and moisture of air inside the home have been directly linked to a surprisingly extensive number of medical issues. The Environmental Protection Agency cites indoor air quality as a top environmental health risk that is far more likely to affect personal health than pollution found outdoors.
Though often overlooked, humidity could be the underlying factor behind difficulty sleeping, fatigue, allergies, persistent upper respiratory issues, and a host of other symptoms. High humidity in the home has been associated with upper respiratory issues, including increased susceptibility to infection, wheezing, development or worsening of allergies, sinus problems, as well as exacerbation of asthma and COPD symptoms. High humidity levels are also commonly linked to feelings of dizziness, fatigue, nausea, frequent headaches, and muscle pain and cramps. In extreme cases, high humidity combined with high temperatures can even lead to heatstroke and heart failure, especially in more susceptible children and older people.
Low humidity may be less noticeable in terms of comfort, but inadequate moisture in the home can be just as detrimental to health as overly humid environments. The symptoms of dry air in the home are usually manifested in the skin and upper respiratory system. Moisture deficient air leads to dry skin, chapped lips, and irritated lungs, throat, and nose. The drying out of mucous membranes makes the body much more susceptible to cold, flu, and cough, hence why the height of cold and flu season occurs during the coldest, driest portion of the year.
Our bodies naturally decrease internal core temperature, which combined with circadian rhythm signals its time for bed, but when humidity is elevated the body’s ability to cool itself is diminished. This not only makes it incredibly difficult to fall asleep but can also disrupt the quality and duration of sleep. Low humidity is also a common culprit behind snoring and nighttime wheezing, which occur as a result of dry sinuses and throat, and can lead to long-term respiratory issues with sustained exposure to overly dry air.
Children and older people are much more susceptible to the ill effects of humidity, as their bodies are not as well-equipped to adjust to changes in temperature and humidity, and their respiratory systems are more susceptible to damage caused by breathing low-quality air. The very old and very young also have more difficulty with temperature regulation, which can result in difficulty staying warm. For this reason, doctors recommend maintaining indoor humidity at the upper end of the healthy humidity range (around 55–60%) to ensure the comfort of children and older people in the home. This can easily be achieved by strategically placing a humidifier in nurseries and bedrooms, particularly during colder months.
Beyond the health of inhabitants, sustained dampness inside can cause serious damage to your home and belongings. Moisture is especially damaging to woods in the home and can cause moisture pockets to form within walls, which not only causes the paint to peel away from the walls but if enough forms the drywall can become compromised and have to be replaced entirely. Hardwood flooring is also susceptible to moisture damage in the form of shrinking and warping. Carpets are known to be an ideal environment for mould and mildew if exposed to access moisture, and once contaminated, carpets will emit a foul, musty odour and usually have to be replaced entirely. Humidity can also shorten the life of electronic devices in your home, and damage your clothing and furniture.