Life requires a delicate balance against the elements. Not too cold, not too hot. Not too moist, not too dry. Existence within those parameters makes for comfortable and healthy living. Outside of them, though, lies a breeding ground for conditions that often lead to illness and disease. It can be a matter of life and death.
Our bodies are 75% water. Our brains are up to 85%. All of our internal processes require robust hydration, and a lack of water can cause numerous adverse health effects ranging from dry mucus membranes and nosebleeds to serious infections. In F. Batmanghelidj’s book, The Body’s Many Cries for Water, the author asserts: “Chronic, unintentional dehydration is the origin of most pain and degenerative diseases in the human body.”
During the winter months — in cold climates — the humidity can drop to levels well below the human comfort zone. Air leaks that let cold air into your home allow moisture to be sucked right out of the building. The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) suggests you maintain indoor relative humidity (RH) at 30-60%RH, but many people start experiencing difficulties below 40%RH.
When humidity is low, adding moisture to the air is vital, but you must do it properly or else you’ll end up with a different set of problems. Above 60%RH and you begin to create an environment conducive to mold growth, dust mites, bacteria and other unwanted guests. The key, of course, is finding the right balance.
Here’s the healthy home mantra: Don’t modify what you don’t quantify. That means that before you do anything, know what you’re dealing with.
Humidity gauges, also known as hygrometers, are inexpensive and provide the information you need to decide whether to add or remove moisture from your home. I prefer the ones with remote sensors, which allow the monitoring of areas that are out of sight/out of mind, such as crawlspaces, attics, outbuildings, etc. I use one of these to keep an eye on the conditions in my kitchen, outside, and basement.
Choosing the Right Humidifier for Your Home
Whole Home vs. Standalone
Once you’ve quantified the RH of your living spaces, the next important decision is choosing how to add humidity, around which there is much confusion. In essence, you are choosing between whole-home systems and standalone units.
Whole-home systems are installed in the air handler of a forced-air system, while standalone units, which can be bought retail, simply plug into the wall in areas where you spend the most time, like a bedroom.
My primary gripe with whole-home systems (also referred to as “inline” systems) is their history of malfunctioning and their tendency to promote microbial growth. The old drum types were the worst: Not only did they fail, but they allowed mold and bacteria to proliferate in the airflow of your ventilation system. If you have a humidifier built into your current HVAC system, have it evaluated by a professional to ensure you aren’t pumping other things into your ducts aside from the intended moisture.
Recently there have been some significant improvements in the way these inline systems are designed, which has lessened my concern. But I still prefer the standalone units because they are easier to maintain, and because their visibility is a consistent reminder to do so.
Hot vs. Cool
There has long been a debate about the advantages and disadvantages of cool mist versus warm mist. Pediatricians have historically recommended cool mist over steam, primarily to reduce the chance of burns. But with the units currently on the market, that’s no longer a common issue. It’s my professional opinion that warm mist and steam/vaporizer types are far better in terms of effectiveness and cleanliness.
Cool mist types utilize an evaporative wick and a fan. Water from a reservoir is forced to evaporate into the ambient air. These units are quiet and require little energy, but they are also the most likely to become veritable Petri dishes, fostering the growth of a wide range of microbes very similar to that of whole-home humidifiers discussed above. And though they don’t add heat to the room in which they’re being operated, cool mist units take a long time to bring the humidity up and require daily cleaning. When you’re not using them, they should be emptied and dried thoroughly.
There are also ultrasonic humidifiers, which utilize high-frequency sound waves to emit a fine, cool fog. They are quiet and efficient but often have the pesky side effect of creating white, mineral dust that can get all over your stuff. Some of them come with mineral absorption pads, which need to be replaced regularly to help minimize this issue. Despite the fact that many of these units come with anti-microbial features, they still should be cleaned out daily. Like all humidifiers, when not in use they should be emptied and dried thoroughly.
Steamer/vaporizer types are very effective at increasing the humidity quickly but they add heat to the room and sometimes create a somewhat muggy atmosphere. While it’s always important to monitor humidity to make sure you’re in the safe zone (40-60%RH) it’s especially true with steamer/vaporizer humidifiers. Many of them come with built-in humidistats, so they turn off automatically when RH reaches the target setting. They don’t need to be cleaned as often since the steam is such an effective antimicrobial, but you need to make sure not to leave the water in the reservoir for more than two days. Some people find that adding a tablespoon of 3% hydrogen peroxide or an ounce of colloidal silver does wonders to keep the water in the reservoir fresh.
Although steamer/vaporizers require more energy than cool mist and ultrasonic, the difference is more or less negligible, pulling about the same draw as a 40-watt light bulb. And, unlike ultrasonic units, there are no issues with mineral dust dispersal, but you will still find mineral buildup inside the reservoir when you clean them. The biggest gripe I hear is that they can be a burn risk if you have little ones running around, and there’s not much you can do about that. In this case, I would suggest going with the warm mist type.
In fact, warm mist units are the best of both worlds. They experience lower microbial activity than the cool mist variety and are very effective at adding moisture. Many of them have ultraviolet lights to help augment the antimicrobial nature of the hot water vapor, which is allowed to cool before leaving the unit, reducing the burn risk almost entirely. They do add some warmth to the room and can also create a muggy environment, especially if you let them run the humidity up above 60%, but as long as that doesn’t happen, they are an excellent choice.
A Word on Maintenance
All humidifiers require maintenance to avoid becoming breeding grounds for biological contaminants. Make sure you read the instructions thoroughly. I strongly recommend avoiding harsh chemicals, such as bleach, when cleaning your humidifier. For one, you don’t want that stuff being vaporized and put into the air. And there’s also the chance that when that vapor reacts with the unit’s plastic housing, it will create other chemical compounds that you wouldn’t want to breathe, either.
Humidity control is the most important aspect of healthy indoor air. Too little and you’ll find yourself wrestling with constant colds, sinus issues and skin problems. Too much and you’ll end up with an increased allergen load in the house due to dust mites and mold growth. But by following the guidance above and keeping humidity levels between 40-60%, you and your family will be sufficiently well-balanced to enjoy all that winter has to offer.
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