Could Your Humidifier Help Prevent COVID-19?


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Key Takeaways

  • A new study from MIT shows humid conditions indoors may help prevent the transmission of COVID-19. 
  • While the average humidity percentage is about 30 to 50 percent, researchers suggest increasing it to a 40 to 60 percent “sweet spot” to protect against COVID-19. 
  • Though the study is promising, it’s important to still continue to follow other virus protection protocols as well.

The winter season is in full swing and rates of several illnesses, including COVID-19, RSV, and the flu, have been on the rise. With many people hunkering down indoors, sickness has the opportunity to move around more swiftly, especially because heat causes a dry environment to do so. 

As you crank up the heat in your home, you may want to also consider turning up the moisture as well. A new study from MIT shows an increase in humidity could help prevent the spread of COVID.  

The Humidity "Sweet Spot" To Prevent COVID-19

You may already be ventilating when indoors, especially when you gather with a group, in order to help prevent the spread of COVID. While ventilation is still important, tacking on increased humidity indoors seems to add another layer of protection, according to the MIT study. 

Researchers from MIT analyzed COVID data along with meteorological measurements from 121 countries between January 2020 and August 2020. The team compared outbreaks in different regions (pre-vaccines) to the relative humidity levels of the region.

What the researchers found was that when an area experienced a rise in COVID cases and deaths, the estimated indoor relative humidity in the region was either lower than 40 percent or higher than 60 percent no matter the season.

“Indoor ventilation is still critical,” study co-author Lydia Bourouiba tells MIT News. “However, we find that maintaining an indoor relative humidity in that sweet spot — of 40 to 60 percent — is associated with reduced Covid-19 cases and deaths.”

That so-called “sweet spot” of 40 to 60 percent isn’t what the average person is used to, though.  A typical humidity range is between 30 and 50 percent while an airplane cabin’s humidity is about 20 percent.

That intermediate humidity is key because, the study also found, too much humidity could potentially have the opposite effect and make COVID more transmissible and too little won’t stop the spread much. 

The team also found humidity had an effect on the outcomes of the infected person. Humidity can affect a person’s immune functions and how COVID moves through their body, among other outcomes.

Linking Humidity to Seasonal COVID Changes

Living with COVID for three years, we’ve come to see a pattern of cases decreasing in the summer or warmer months and increasing as the weather gets colder. While there are suspicions and some evidence that COVID goes through seasonal swings, research on the subject is not conclusive.

What the MIT study gives insight into is the effect of controlled, indoor climates, as opposed to the outdoors, on COVID. This finding is significant because while we can’t control the weather outside, we may have more power over the conditions inside of our homes which allows for more informed protection, seasonal swings or not. 

“By maintaining a certain temperature and humidity level, preliminary data shows signs that it can modulate the spread and severity of COVID-19 outbreaks indoors,” says Bernadette Boden Albala, MPH, DrPH, founding dean of the UCI Program in Public Health. “The multifaceted effort to minimize indoor viral transmissibility is promising as we are experiencing a surge in COVID-19, RSV, and flu viral infections.”

How To Increase Humidity in Your Home

There are a few different methods and ways to increase, or decrease, the humidity of your home, but first it’s important to see just how humid it actually is in there. Humidity levels can be measured with a hygrometer, a device that looks similar to a thermometer and determines the amount of moisture in the air. Some humidifiers come with these already built in.

Once you know what the humidity levels are you can set them to that ideal range—between 40 and 60 percent. 

Some homes are equipped or can be outfitted with central humidifiers which are built into a house’s heating and air conditioning systems. But other options, like the various types of room humidifiers work too. 

Though the MIT research into humidity is a promising new prevention against COVID, experts still advise continued following of other COVID protocols as well to ensure the most effective safeguarding against the virus. 

It is still imperative that we encourage individuals to wear masks when feeling ill and frequently washing their hands, but this potential intervention can only better protect our communities from widespread COVID-19 infection.


“It is still imperative that we encourage individuals to wear masks when feeling ill and frequently wash their hands, but this potential intervention can only better protect our communities from widespread COVID-19 infection,” says Boden Albala. “More work is needed to understand the mechanisms behind such results as well as other studies which replicate the results in a clinical trial format.”

What This Means For You

A new study suggests adding humidity inside your home could help prevent the transmission of COVID. If you don’t already have a hydrometer to measure the humidity in your home, that may be a good place to start. Humidifiers in homes help with many different ailments, including asthma and allergies, so investing in one to help prevent COVID transmission is an added bonus. Even with a humidifier, continue to take other preventative measures, like hand-washing, to prevent COVID.

4 Sources
Verywell Family uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Verheyen CA, Bourouiba L. Associations between indoor relative humidity and global COVID-19 outcomesJ R Soc Interface. 2022;19(196):20210865. doi:10.1098/rsif.2021.0865

  2. MIT News. Keeping indoor humidity levels at a “sweet spot” may reduce spread of Covid-19.

  3. MIT News, Keeping indoor humidity levels at a “sweet spot” may reduce spread of Covid-19

  4. Mayo Clinic, Humidifiers: Ease skin, breathing symptoms.

By Emily Nadal
Emily Nadal is a freelance writer specializing in pregnancy and maternal health. She holds a master's degree in health and science journalism from the Craig Newmark Graduate School of Journalism. She also has experience working in television news at local stations in New York City.