A common household device designed to improve comfort may actually pose a hidden health risk, according to new guidance from the Centers for Disease Control and Prevention (CDC). Humidifiers, increasingly popular in American homes, can harbor germs and potentially make people sick if not cleaned and maintained properly.
These devices are widely used to ease dry skin, relieve congestion, and improve sleep by releasing moisture into the air. However, the CDC warns that humidifiers can also become breeding grounds for harmful pathogens if precautions are not taken.
“Don’t let germs get cozy in your humidifier,” the CDC cautioned. “Germs can grow in humidifiers and spread through the mist. To stay healthy and prevent germs from growing in your humidifier, clean water-using devices, flush faucets, and take other steps to avoid these germs.”
The agency explained that bacteria, fungi, and even amoebas can form biofilms—slimy, glue-like substances that help germs stick to surfaces like the inside of pipes or humidifier reservoirs. These biofilms protect germs from disinfectants, allowing them to survive, multiply, and potentially spread through the mist released by the device.
“Respiratory infections can be acquired from exposure to pathogens contained either in droplets or droplet nuclei,” the CDC added. The pathogens found in biofilms can lead to infections affecting the lungs, brain, eyes, and skin.
The CDC emphasizes that while most healthy individuals are unlikely to become seriously ill from these germs, certain groups face higher risks. These include infants under six months, adults over 50, individuals with chronic lung conditions, weakened immune systems, diabetes, kidney or liver disease, smokers, and contact lens wearers.
To minimize risk, the CDC recommends several important steps for humidifier users:
- Empty the water reservoir daily and allow it to air dry.
- Clean the humidifier according to the manufacturer’s instructions.
- Use distilled or demineralized water to prevent mineral buildup and dispersion.
- Flush faucets and showerheads if not used recently, and run hot water before using them.
Dirty or stagnant water in humidifier tanks, particularly in those that have been left unused, can become a hotbed for bacteria and mold. Regular maintenance and cleaning are essential to keeping the air and household members healthy.
As the use of humidifiers continues to grow, especially during dry seasons, the CDC urges all users to take proactive steps to prevent avoidable illness from contaminated indoor air.