Shop
Smart watering systems!
Full autonomy, soil humidity sensors, rain sensor, adjustments for wheater forecast and tank water level
Why Relative Humidity is So Important for Health
Humidity and Health
The key point about air humidity, much like radiation, is that humans lack a dedicated sensory organ capable of perceiving this critical health indicator.
We are very good at sensing temperature, but we can only judge humidity by indirect signs:
- Dry skin, dry eyes, cracked lips, frequent colds, discomfort when wearing contact lenses, and asthmatic children—all of these may indicate that the humidity level in your home is below normal.
- Feeling stuffy, excessive sweating, persistent skin irritations, and vascular problems—these may suggest that the humidity in your home is too high.
A special note on allergies. Both low and high humidity levels are bad for allergy sufferers. In the first case, dry air allows household dust to remain suspended for hours, triggering attacks. In the second case, mold spores and other microorganisms thrive in a warm and humid environment, creating an ideal breeding ground.
How Does Humidity Affect Health?
In simple terms:
- At low humidity, your mucous membranes dry out, and the drier they are, the harder it is for them to fight external infections. This leads to colds, viruses, and localized inflammations.
- At high humidity, mold and fungi develop actively, and their spores are generally harmful to health. Additionally, at higher temperatures, sweat does not evaporate well from the skin, leading to excessive sweating and overloading the cardiovascular system. Plus, there’s the risk of overheating.
Do not try to diagnose yourself based on humidity levels. Otherwise, you may end up like the character in the old joke who, after reading a medical encyclopedia, finds that he has every disease listed. The right approach is to buy a home humidity meter, monitor its readings for a week or two (carefully recording them), and then discuss the results with a doctor.
Physical Model
Everything You Need to Know to Control Humidity
- Relative humidity is the key measure of indoor air quality. It is expressed in % and indicates the air’s ability to absorb additional moisture. For example, if the humidity is 15%, the air is extremely dry; wet clothes will dry very quickly, and most people will experience respiratory problems. At 100% humidity, wet laundry will never dry, and in a warm climate, it will soon be covered with mold.
- The optimal humidity for most people, paper books, paintings, wooden furniture, and musical instruments is between 40% and 60%.
- A crucial and fundamental factor for indoor climate: As temperature increases, relative humidity drops significantly.
Why does this happen? The graph (blue line) shows the relationship between temperature and the maximum amount of water vapor that atmospheric air can hold.What happens if you add more water vapor to air that already has 100% humidity at the same temperature? The excess moisture will condense into liquid water, and as a result, the amount of vapor in the air will remain the same.
That is, how many grams of water vapor are contained in 1m³ of air at 100% humidity and a given temperature.
As shown on the graph, if you take air at 100% humidity at 0°C and heat it to 20°C, the relative humidity drops to just 27.7%—far below the comfortable norm (4.8/17.3 = 27.7%).
If the outside temperature is −10°C and humidity is still 100% (2.4 g/m³), then without a humidifier, the relative humidity indoors will be 2.4/17.3 = 13.8%. This is extremely uncomfortable: wooden furniture warps, and the risk of allergies, bronchitis, dry eyes, and asthma attacks rises sharply.
How to Maintain Comfortable Indoor Humidity?
There is only one solution - a humidifier.
It is essential to understand why aquariums, decorative fountains, houseplants, wet towels, and other DIY methods are completely ineffective. Only a full-fledged and sufficiently powerful humidifier will work.
Let’s do a quick back-of-the-envelope calculation to estimate how much moisture needs to be added to the ventilation system for comfortable living conditions.
If the outdoor temperature is 0°C with 50% humidity, and you want to maintain the same 50% humidity indoors at 20°C, you need to add 8.65 — 2.40 = 6.25 g of water vapor per cubic meter of incoming air (see orange graph).
According to regulations, the comfortable air exchange rate per person should be around 30m³—50m³ per hour. That means, for a typical family of three to four people, the ventilation system should handle 100m³—200m³ per hour.
This results in: 6.5 × 100(200) × 24 = 15,600 to 31,200 grams of water vapor, or 1.5 to 3 buckets of water per day!
Note that this is a conservative estimate. Outdoor temperatures can be much lower than 0°C, and indoor temperatures may often be set above 20°C.
So, buy a good humidifier and set it up for continuous automatic operation with humidity feedback, as recommended for a Smart Home system.
Choosing the Right Humidifier
More details on what to look for when selecting a humidifier can be found in a separate article.
PS:
In a hot and humid climate, the situation is reversed. When an air conditioner operates, the hot and humid air from outside is cooled, increasing relative humidity up to 100% (see graphs). To maintain minimally comfortable indoor conditions, excess moisture must be removed. The amount of moisture removal is also measured in buckets, but fortunately, modern split systems handle this task well.
You may have noticed that on a hot day, condensate drains from an air conditioner through a special tube. In some cases, over-dehumidification can occur, making indoor air uncomfortably dry.
The best solution, in my opinion, is once again a Smart Home system that automatically controls air humidity in real-time, managing all climate systems from a central hub with humidity feedback.
