Study: Flu and Other Viruses Cannot Survive in Humid Air, Thrive in Dry Air

Make sure your humidifier is running whenever your heater is! Researchers found raising indoor humidity destroyed 100% of airborne flu viruses within 24 hours.

While many of us are obsessed with maintaining a certain temperature in our homes and offices, few of us ever stop to think about another important aspect of climate control — humidity.

When air conditioners remove heat from the air, they’re also removing humidity, which can make indoor air unnaturally dry unless you’re in a very humid environment.

In the winter, it’s even worse, as cold air is dry to start with and most heaters make it even dryer.

This may be the reason flu season is in the winter, researchers are discovering.

Several studies over the last few years have found that raising indoor humidity to above 43% (50% is ideal) stops the flu virus dead in its tracks.

In a 2013 study, scientists used a cough simulator to send the flu virus whirling into the air and measured how long it lived at various levels of humidity.

At humidity levels less than 23%, up to 77% of the virus remained viable in the air an hour later.

At humidity levels greater than 43%, as little as 14% of the virus remained viable an hour later.

23 hours later, 100% of the viruses in the humid air were all dead, while 60 percent still survived in dry conditions, a 2009 study found.

Until recently, scientists have been “stumped about why some parts of the world have such a pronounced winter flu season with almost no flu activity in warmer months,” CNN reports.

Now we know. It’s not the cold that makes us sick. It’s the dry air.

Here are 7 other reasons to turn up the humidity:

1. Asthma

A 2016 study found that teachers in low-humidity classrooms had an increased risk of allergy and asthma symptoms.

The study’s authors note that “schools frequently have trouble maintaining indoor relative humidity within the optimum range (40-60%) for reducing allergens and irritants.”

2. Coughing

Humidity of around 50 percent can also reduce “dry, unproductive coughing,” according to Medical News Today:

“Adding humidity to the air can get more moisture into the airways, which can make a cough more productive. A productive cough releases trapped or sticky phlegm.”

3. Snoring

Increasing the amount of moisture in the air can also reduce snoring, she adds.

“If the air is dry, a person’s airways are less likely to be sufficiently lubricated, which can make snoring worse.”

4. Sick Building Syndrome

A 1994 study found that increasing humidity can help with symptoms of “sick building syndrome,” which include headache, eye, nose, and throat irritation, fatigue, dizziness and nausea thought to result from exhaust, aerosols, microorganisms, and volatile organic compounds circulating in recycled air.

Raising the humidity in hospitals to 40-45% significantly decreased the sensation of dryness, airway symptoms and static electricity.

5. Dry skin and hair

Keeping a humidifier running in the winter can also reduce dry, cracked skin, frizzy hair and chapped lips.

6. Houseplants and furniture

Even your houseplants, wood floors and wooden furniture will appreciate you keeping your indoor air moist. Humidity helps houseplants stay vibrant and wood last longer.

7. Save money on heat

Moisture helps hold heat in the air, meaning your heater won’t have to work as hard and you’ll save on your heating bill.

This is the 5-gallon whole-house humidifer we use in our home, so we only have to fill it up every other day.

And here’s a hydrometer you can use to make sure the humidity is reaching every room.