Why Humidification is important to Your Health
On average people spend the majority of their time indoors. If we are spending that much time inside a building, we want it to be a space that promotes health and wellness. Recent studies by Dr. Stephanie Taylor and ASHRAE have shown this may not be the case.
New building construction is designed to maximize the operating efficiency and minimize costs. Thus, tighter buildings, where there is minimal heat/cooling air loss and minimal fresh air entry. This creates a space with dryer and warmer inside air. What has been discovered is that this design increases the spread of airborne pathogens.
What are we missing? Humidification is an often-overlooked feature of a building system. A typical building tends to focus primarily on managing high humidity during the summer months, while ignoring the drawbacks to low humidity spaces during winter operation. Buildings in cold weather climates that operate without humidification systems often fall well below the ASHRAE 55 thermal environmental conditions for human occupancy (40%60% RH). The ASHRAE Position Document on Infectious Aerosols states: “scientific literature generally reflects the most unfavorable survival for microorganisms [is] when the relative humidity is between 40 and 60 percent.”
When the mechanical heating system introduces cold, dry air into the building without adding additional moisture to the air stream, the result is a 72-degree space consisting of roughly 10%-15% relative humidity (RH). Complaints due to low humidity levels include eye irritation, skin dryness, respiratory irritation, and increased static shock. Additionally, building operators managing low humidity tenant spaces often report their tenants complaining the space “feels cold” even when the dry bulb is registering at 72F-74F. This is partly due to the fact that humans have no skin sensors for dryness leading to misplaced complaints about temperature.
Did you know that when you are in a dry room (less than 30% RH) the air pulls moisture from your body?
According to ASHRAE – “when indoor air is less than 40% RH, the effective, natural immunological defenses of human airways, eyes and skin are impaired. The loss of moisture from these tissues leaves occupants significantly more vulnerable to infectious, inflammatory and allergic diseases.” The mild dehydration from a dry air water loss will also impair brain function, fatigue, and slows down our ability to focus. Ever get hit by a wave of tiredness at 2pm, that’s often a result of the lack of moisture in the air.
Not only is your body more susceptible in this condition, air pathogens stay buoyant and more viable for longer periods of time. While humidified air is denser weighing down pathogens and making harder for them to travel through the air.
It’s double fold, our systems are more vulnerable and airborne pathogens can spread more easily which is why there is a flu season. So, what do we do? There is a sweet spot of 40-60% relative humidity that is ideal for health and well-being.
Now the hitch: many buildings are not equipped with functioning or well designed and maintained humidification systems. As well, most buildings cannot sustain humidity levels above 33% without risking condensation due to leaks on the curtain wall or around windows. ASHRAE’s minimum of 40% RH may be unreachable during the coldest days of the year. These studies are relatively new and only really brought to light by COVID. We highly recommend building managers, operators, and/or owners reach out to CTM to discuss this balance between what is recommended and what is achievable.
This is just the tip of the iceberg of this topic, if you are interested there is a lot of information out there, Dr. Stephanie Taylor is a leader in the field and has a number of YouTube videos which are very informative.