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Is Too Much Humidity Hurting Your Health?

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Last Updated on October 7, 2020

visible signs of too much humidity on an exterior door

You may have read recent research that suggests raising indoor humidity levels may help to deactivate coronavirus particles. During the winter months when our spaces are closed up and heated, humidity levels can drop to extremely low levels (as low as 20 percent).

Unfortunately, the COVID-19 virus has been shown to thrive and remain viable for longer periods in these low-humidity conditions. (Controlling humidity is just one way HVAC can help in the fight to prevent COVID. Get our guide to HVAC Strategies for COVID to learn more.)

guide to HVAC strategies for COVID

However, too much indoor humidity can also cause health problems. For example, viruses are known to spread more easily in humidity levels higher than 60 percent. So what is considered high humidity and what are safe indoor humidity levels?

And most importantly, how do indoor humidity levels affect your body and your health?

We’ll share some facts about the adverse effects of too much humidity beyond personal discomfort, as well as common causes of high humidity indoors.

Let’s start with the optimal humidity levels and how much is detrimental to your health and well-being.

How much is too much humidity?

Experts generally agree that the ideal indoor humidity levels for comfort and for avoiding health effects are between 35 and 60 percent. When you’re spending time in a home or workplace with humidity levels in excess of 60 percent, it’s increasingly likely that you will experience certain health issues.

Let’s look at the direct effects on the body from too much humidity. However, it’s even more likely that you’ll experience the indirect effects; so we’ll also explain how humidity alters your environment, and how those effects can be detrimental to your health.

Humidity and health: the direct effects can be deadly

Whether it’s indoors or outdoors, too much humidity combined with high temperatures can cause our bodies to overheat. When that happens, the consequences can be dangerous.

Do you ever wonder why hot, sticky, humid air feels so much more uncomfortable than hot, dry air? It’s because humidity impedes your body’s ability to regulate body temperature and cool down. Too much humidity can actually cause your body temperature to rise.

Here’s how it works in a nutshell. When temperatures get too hot, your body has defense mechanisms that kick in to keep your internal temperature steady. These include:

  • sweating
  • increased respiration
  • altered blood circulation

Sweating is an important one, and is greatly impeded by too much humidity in the air. Sweating cools the body when the moisture evaporates from the skin. However, when the air is already saturated with water vapor (as it is when humidity levels rise to 70 percent and higher), sweat can’t evaporate. So instead of cooling down, you just feel hotter and stickier.

At that point, the body is forced to resort to other means to try to cool off. That’s why you may notice yourself breathing more rapidly as you get increasingly hotter. Your heart pumps more blood to your extremities, and less to your internal organs and your brain. That’s why you feel sluggish and foggy. You may begin feeling light-headed or even faint. You may also feel muscle cramps, especially in your legs.

With the loss of fluids, salt and electrolytes, the body overheats. Eventually, if your body can’t maintain temperature, you can develop heat exhaustion or heat stroke, which can be fatal.

What are the indirect effects of too much humidity on your health?

While the direct effects of too much humidity & heat can be dangerous, in most cases you will know you’re in danger and find a way to cool off. However, the indirect effects of high humidity can be more insidious. Humidity can cause changes in your indoor environment that can cause you to become ill.

Related article: Summer Humidity is Scarier Than You Think

Bacteria and viruses take hold in humid conditions

Spending time in an environment with too much humidity can actually make you sick, especially from respiratory infections.

The bacteria and viruses that cause illness thrive and grow in air that’s above 60 percent relative humidity.

What’s more, humid air also makes those contaminants stay airborne for a longer period of time before settling onto surfaces. So when you’re in a humid office and people are sneezing and coughing all around you, those nasty germs are sticking around and multiplying. And it’s more likely that you will breathe them in.

Allergens kick into high gear
According to a report in Environmental Health Perspectives, published by the National Institute of Health, too much humidity leads to higher levels of dust mites and fungi, two of the worst culprits for indoor allergy sufferers.

Asthma sufferers beware
Mold and fungi are known to exacerbate respiratory conditions such as asthma. Even people who don’t normally have allergies or asthma can experience hypersensitivity reactions from fungi that grow in conditions with too much humidity. Most of these microorganisms grow like crazy in relative humidity levels in excess of 75%.

Even if you don’t see them, they can be present in bathrooms, kitchens, carpets and furnishings, and the ceiling tiles in your office. They might even be growing in your air conditioning ductwork.

Humidity increases airborne chemical contaminants
Organic contaminants like bacteria, mold and dust mites aren’t the only things that get worse in air with too much humidity. Airborne chemicals that cause adverse physical effects also increase as the humidity goes up.

Everyday building materials like carpet and wood products release chemicals such as formaldehyde into the air. This is called “off gassing.” When there’s too much humidity in the air, the concentration of these noxious chemicals rises due to the reaction of the chemicals with water vapor. Even low-level exposure to those chemicals can make people experience skin, eye and throat irritation as well as respiratory symptoms.

This problem is increasing with the construction of more energy-efficient buildings that may have low fresh air ventilation rates. That’s why it’s so important for modern buildings to maintain proper humidity levels for good indoor air quality.

3 common causes of too much humidity in your space

Now that you know the facts about humidity and health problems, here’s what you need to know about the causes of too much humidity. Then you’ll be equipped to deal with the problem and feel better in your space.

1. Inadequate ventilation
A lack of fresh air can increase the levels of both chemical and organic pathogens that cause illness as well as discomfort from humidity. Changes to the HVAC design by a qualified professional, such as adding makeup air or re-routing ductwork, can make a big difference in humidity levels.

Related article: 4 Reasons You Need HVAC Design for Your Air Conditioning Install

2. An oversized air conditioner
It’s a more common situation than you might imagine. Building contractors often make the mistake of installing air conditioners that are too powerful for the space. As a result, the unit turns on an off frequently, never running long enough to remove humidity from the air.

Believe it or not, you might need to downgrade your HVAC equipment to control humidity in your space.

Related article: New York HVAC Systems: 8 Reasons Bigger is Not Always Better

3. Neglected AC maintenance
When your equipment has been neglected and no longer works efficiently, you can end up with too much humidity in your space. Getting a tune up and a good cleaning can restore it to proper working condition.

Humidity is only one of many problems caused by poor maintenance of your AC equipment. And those problems are costing you in ways you probably don’t even know about. Learn more from this informative guide to Calculating the Hidden Costs of Poor HVAC Maintenance.

Get the guide to understanding your HVAC System's hidden costs.