Can a Humidifier Prevent the Spread of Viruses?

Using a humidifier may provide some protection against the spread of viruses by maintaining optimal indoor humidity levels between 40-60%, according to research. However, good hygiene, masking, distancing and vaccination remain the best ways to avoid illness.

How Does Humidity Affect Viruses?

Indoor humidity levels have an impact on how viruses are transmitted from person to person. Here’s an overview of the evidence:、

• Low humidity below 40% allows viral droplets to remain airborne for longer periods. This increases the chances of inhaling infectious particles.
• Conversely, higher humidity causes water droplets to accumulate and fall out of the air faster. This reduces airborne transmission of viruses.
• Maintaining indoor humidity between 40-60% is optimal for minimizing the survival and spread of many viruses, including coronaviruses, influenza, rhinoviruses and more.

By increasing moisture levels, humidifiers may be able to create indoor conditions that are less favorable for airborne viruses to transmit infections.

Are Humidifiers Effective at Raising Humidity to Prevent Viruses?

Humidifiers can increase humidity levels, but there are some caveats on their effectiveness against viruses:

• Portable humidifiers typically only raise humidity in a single room, not an entire home.
• Larger console or whole-home humidifiers controlled by a central humidistat are better able to regulate humidity in all living spaces.
• Frequent cleaning and maintenance is required to prevent mold and bacteria buildup in humidifiers.
• Monitoring indoor humidity with a hygrometer is important to maintain 40-60% target levels.

Used properly in smaller spaces, portable humidifiers may offer some virus protection. But whole-home systems provide the most effective humidity regulation throughout a living area.

What Factors Impact a Humidifier’s Ability to Slow Viruses?

Here are some key considerations when using a humidifier to potentially reduce virus transmission:

• The humidifier must raise humidity high enough to reach the optimal 40-60% range in order to impact virus spread.^[2]
• Models that only raise humidity slightly above baseline levels may not provide enough moisture to inhibit viruses.
• Cleaning humidifiers regularly prevents microbial growth and spread of molds that trigger allergies.
• Humidifiers are likely most effective during colder winter months when indoor air is extremely dry.
• Monitoring humidity with a hygrometer allows maintaining ideal 40-60% levels.

By using the proper humidifier for your environment, cleaning it regularly, and monitoring humidity, you can create conditions that may hinder viruses.

The Bottom Line: Do Humidifiers Prevent Viruses?

Maintaining indoor air at 40-60% relative humidity can help reduce the infection rate of viruses and prevent seasonal illnesses. However, humidifiers should not replace other protective measures like:

• Washing hands frequently
• Avoiding touching the face
• Disinfecting high-touch surfaces
• Physical distancing
• Correctly wearing face masks
• Getting vaccinated and boosted against diseases like flu and COVID-19

Humidifiers are most effective when used alongside good hygiene habits, masks, distancing and vaccines for layered protection. Think of proper humidity control as one additional strategy for potentially decreasing viruses this cold and flu season.