Your humidifier could be affecting indoor air quality, says expert
With flu rates at their highest levels in 15 years and an unusually late peak compared to previous seasons, those experiencing symptoms are looking for relief. Many turn to humidifiers to manage symptoms like a stuffy nose or dry throat. However, a Virginia Tech environmental engineering expert warns that improper use of humidifiers could do more harm than good.
How do ultrasonic humidifiers release toxic heavy metals?
“Ultrasonic humidifiers create a fine mist by vibrating water into tiny droplets,” said Andrea Dietrich, professor in civil and environmental engineering at Virginia Tech. “As the water evaporates into the air, any dissolved minerals—including potentially toxic heavy metals like arsenic, cadmium, lead, and manganese—are left behind as airborne particles (also known as rock dust or white dust). If the water used to fill the humidifier contains these metals, they can become airborne and be inhaled, posing potential health risks.”
Tips for safe humidifier use
With flu season is still in full swing and allergy season on the horizon, Dietrich shared advice on how to make the use of your at-home, ultrasonic humidifier a little safer.
“Best practice is to fill your ultrasonic humidifier with distilled or reverse osmosis water, which contains very few or no minerals,” Dietrich said. “Water treated with a water softener or carbon/ ion exchange filter to purify tap water should not be used. These replace minerals like calcium and magnesium with sodium and potassium, which will still generate dried minerals or rock dust when used in an ultrasonic humidifier.”
Consumers can also choose a humidifier that is not based on ultrasonic technology. Dietrich said thermal humidifiers are a great way to add moisture to the air without adding dried minerals or rock dust.
“Thermal units are known as warm mist humidifiers, vaporizers, or steam vaporizers,” she said. “Evaporative humidifiers are another option and use a wick to adsorb a layer of water, which is then evaporated by a fan.”
Regardless of the type of humidifier, Dietrich stressed the importance of regular cleaning and maintenance to prevent microbial growth.
“Avoiding chemical disinfectants is also important, as they can become airborne and cause harm,” she said.
Why is tap water use in humidifiers problematic?
“When safe to drink, tap water can contain dissolved minerals like calcium, magnesium, sodium, iron, manganese, and traces of other metals at or below regulatory levels.” Dietrich said. “When inhaled as airborne particles, these minerals can clog lung passages, exacerbate respiratory issues, and deposit toxic levels of metals in lung tissue. While beneficial when ingested, these minerals are not safe for inhalation.”
Inhaling particles into the lungs is unhealthy for anyone, but certain populations—including children and infants, elderly individuals, and those with respiratory conditions—are most at risk, she explained.
Potential long-term effects of manganese exposure
Dietrich recently published a study on long-term effects of manganese exposure. Manganese is a typical metal in many tap waters.
“The study did not measure manganese levels in the brain or lungs directly; however, inhaling manganese is known to cause lung irritation and neurological effects” she said. “Modeled exposure levels in our study suggested that children’s inhaled dose of manganese from ultrasonic humidifiers could exceed recommended levels, posing risks for neurotoxicity and behavioral issues.”
Other steps to improve indoor air quality
“Increasing ventilation is important because bringing in fresh air can reduce particle concentration,” Dietrich said.” Opening a window can make a big difference. Air purifiers are another option when the weather is not conducive to opening windows and doors.”
She also advised consumers to be mindful of combustion sources and household products.
“Fireplaces, candles, cigarettes, as well as air fresheners, can worsen indoor air quality,” she said.”While there are no U.S. regulations governing indoor air quality in homes, consumers can take proactive steps to maintain good air quality.”
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About Dietrich
Dietrich is a professor in the Charles E. Via, Jr. Department of Civil and Environmental Engineering at Virginia Tech. She has expertise in drinking water quality, treatment, and infrastructure; chemosensory analysis of environmental contaminants and tastes-and-odors in drinking water; fate and transport of organic and inorganic chemicals; and environmental analytical chemistry.
For media inquiries or to schedule an interview, please contact:
Margaret Ashburn | mkashburn@vt.edu | 540-529-0814