Use an ultrasonic humidifier? Tap water could be polluting the air in your home

Winter in many parts of Canada is cold and dry and that means many reach for a humidifier to help with dry skin and breathing issues.

But a new paper out of the University of Alberta shows using anything but distilled water in an ultrasonic humidifier may actually do more harm than good.

“Our study showed that operating an ultrasonic humidifier with tap water resulted in particulate matter concentrations equivalent to a polluted city,” said Ran Zhao, assistant professor in the Department of Chemistry and the corresponding author on the study.

Ultrasonic humidifiers generate humidity by breaking the water into small droplets using a device that vibrates at an ultrasonic frequency. The small water droplets are sent into the air, creating the mist you see outside the humidifier.

While the water evaporates quickly once released into the air, the minerals and salts dissolved in tap water are left behind as particulate matter.

According to the researchers, the chemical species typically found in drinking water are not harmful, but the tiny particles created by these ultrasonic humidifiers can pose a health risk.

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During the study, the scientists collected air quality measurements in a multi-room household.

The results showed fine particulate matter generated by the humidifier in a bedroom on the upper floor was transported through the house due to air circulation.

The water used in the humidifier affected the type of particulate matter, according to the study.

“These particles are so small that they can evade our filtration system in the upper airway and penetrate deep into our respiratory tract,” explained Chester Lau, an undergraduate student in Zhao’s lab and lead author on the paper. “Upon doing so, they also send chemical species associated with them into our bodies.

“Using dirty or contaminated water could cause further detrimental health impacts.”

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According to the study, the bottom line is to use clean water in a humidifier.

“We observed no PM (particulate matter )generated by distilled water purchased from local grocery stores,” Zhao said.

The paper was published in Indoor Air.