Their reaction is a common one among small kids, as a quick perusal of websites, forums or books on parenting will tell you. But new research from the journal of the Canadian Paediatric Society confirms what toddlers have suspected all along: Restroom hand dryers really are too loud. They operate at decibel levels “that are clearly dangerous to children’s hearing.” Loud enough to hurt, and potentially damage children’s sensitive ears.

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The study’s author, Nora Louise Keegan, should know: She’s 13, and her now-published paper draws on research she’s been doing since age 9, when she noticed restroom hand dryers were hurting her ears.

For her study (which notes that its data “was originally presented at the Calgary Youth Science Fair”), Keegan used a professional-grade decibel meter to compile loudness measurements of electric hand dryers at dozens of public restrooms in Alberta from 2015 to 2017. She purposefully selected “locations that children might frequent,” such as schools, parks, restaurants and malls.

For each of the 44 dryers in her final database, Keegan took measurements at various heights and distances to approximate the real-world experience of children and adults of various sizes. She also measured decibel output with and without the presence of a hand in the airstream.

She found that the most common dryers she encountered were astonishingly loud under real-world circumstances. “All Xlerator models, the Blast, and the Dyson Airblade and Airblade V models were louder than 100 dBA [adjusted decibels] when hands were in the air flow, for all measurements,” Keegan writes. That threshold is loud enough that the National Institute of Occupational Safety and Health recommends that adult workers be exposed to no more than 15 minutes of it each day.

A number of the dryer models clocked well above 100 dBA, however, with average loudness levels approaching that of a jackhammer directly adjacent to a person’s ear. At those levels, according to NIOSH calculations, the safe level of exposure for adult workers is measured in mere seconds.

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Keegan notes with concern that children are more vulnerable to damage from loud noise than adults, with sudden noises, like that of a hand dryer, being more harmful than ones that build up over time. Based on a variety of published guidelines, she concludes that “there is no safe duration of exposure for children to sounds greater than a level somewhere between 91 and 111 dBA."

Dyson and Xlerator, two of the major dryer manufacturers, claim decibel levels well below what Keegan recorded. She notes that this is likely due to testing in controlled lab environments with sound-dampening walls, at adult levels of height, and without the presence of hands in dryer airstreams. Each of these factors would serve to reduce decibel output relative to a real-world scenario.

The data “reveals a clear discrepancy between what two major companies claim about their dryers’ sound performance and the real-world operating sound levels of their hand dryers,” Keegan writes. It also “shows the importance of measuring dryer loudness at the location of children’s ears as multiple dryers were much louder at children’s heights than at adult heights.”

Keegan’s research confirms previous work by Shari Salzhauer Berkowitz of Mercy College, who also found that commonly used dryers were producing greater noise than their manufacturers claimed, at levels unsafe for all-day adult exposure.