NEW YORK — Do hand dryers pose a threat to children’s hearing? The answer may be yes, according to a new study published in the official journal of the Canadian Paediatric Society, which found that some of the devices can be as loud as a sporting event or an approaching subway train.

To investigate that question, Nora Keegan, the study’s author, spent more than a year taking hundreds of measurements in public restrooms throughout Calgary, her hometown.

Her interest in the subject was not only academic, but also personal: She’s 13, after all.

“I found my ears hurting and also that children were covering their ears because the hand dryers were too loud, so I wondered if maybe they actually are dangerous to human ears, and I decided to test it,” she said in an interview from a summer camp north of Montreal.

‘WE WOULD JUST GET IN THE CAR AND DRIVE ALL OVER’

Nora’s search began four years ago, in fifth grade, as she was trying to find a project for a science fair. She had complained often to her parents about noisy hand dryers, so she decided to investigate.

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But what Nora found online was lacking: Hand dryer companies didn’t say how they had arrived at noise estimates for their devices.

“I thought maybe they only measured at an adult’s height or only a men’s height, so I decided to test children’s heights as well as women and men’s heights,” she said. She also found that the industry typically tested sound levels at 18 inches from the wall, a distance that seemed too far for a child’s shorter arms.

So, with help from her family and armed with a decibel meter, a ruler and a measuring tape, Nora began touring public restrooms in places children might frequent: schools, libraries and malls, as well as restaurants like Starbucks, Dairy Queen and, of course, the Canadian staple Tim Hortons.

“It was quite a fun adventure,” said her mother, Ms Susan Bannister, who is a pediatrician. “We would just get in the car and drive all over.”

The measurements Nora collected on her first day were encouraging but alarming: After seeing the results, her parents decided to buy her noise-canceling headphones to use as she collected more measurements.

Nora’s research earned her a bronze medal at the science fair that year, and when the time came to choose a project the next year, she opted to collect more data. That decision paid off: In sixth grade, she won the gold and got valuable advice from the judges.

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“A few of them said to me that I should write a paper, so then that got me thinking,” she said.

With help from her father, a family doctor, Nora started to assemble a draft paper in seventh grade. One journal rejected her paper, but Nora kept working and tried another. That publication, Paediatrics & Child Health, published the study in June.

‘IT RAISES SOME REALLY GREAT POINTS’

For each hand dryer, Nora collected 20 measurements, gauging sound from five heights, from two distances and with or without hands present. What she found was striking and straightforward.

“I read a lot of studies in this realm and, honestly, it’s super well-written,” said Mr Frank Wartinger, an audiologist at Children’s Hospital of Philadelphia. “It raises some really great points.”

The noisiest of the 44 hand dryers Nora tested exceeded 100 dBA (a measure of decibels), when hands disrupted the airflow, she found. At that level, hearing loss is possible after about 15 minutes, according to the National Institute on Deafness and Other Communication Disorders. In Canada, toys that emit sounds over that level are banned.

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At 110 dBA, hearing loss is possible in less than two minutes. Sounds at 120 dBA, the highest measurement Nora recorded, can cause pain and ear injury.

The loudest models were Excel Dryer’s Xlerator line, Comac’s Blast, and the Dyson Airblade and Airblade V. The quietest model was One, by Comac, which produced noise at less than 85 dBA in each measurement.

In a statement, Dyson said it encouraged young people to pursue careers in science and engineering, was “delighted” by Nora’s work and was eager to have her meet one of its acoustic engineers.

“We are keen to show Nora how our latest hand dryers are significantly quieter than their predecessors thanks to research and development by our in-house acoustic engineers — perhaps she will want to join the team one day?” it said.

For now, Nora has other plans: She says she’d like to be a marine biologist or find some other way to help the environment.

Neither Excel nor Comac responded to requests for comment.

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‘I’VE LEARNED TO NEVER GIVE UP’

For several reasons, children experience sound differently from adults.

“Their ears are smaller, which means that sounds are louder going in, similar to how if you go into a restroom, your voice is going to be echoing and louder than if you go into a gymnasium,” Mr Wartinger said.

At the same time, he said, adults, who have been desensitised by years of exposure to loud noises, may not even realise the effect that sounds have on their children. He likened it to living in a world where adults permanently wear sunglasses while children go without.

Nora remains committed to the cause.

As she wrote the study in seventh grade, she also worked to create a filter to dampen the noise of the dryers. After nearly giving up, Nora was able to make a working prototype based on a synthetic air filter — the kind used in a furnace — bought from Home Depot.

The final model can reduce the sound of a hand dryer by about 11 dBA, she said, adding that she might try to patent the invention.

As rewarding as seeing her study published and creating the dampener may be, Nora said she was also thankful for what the process had taught her.

“I’ve learned to never give up, because if I had given up then it would never have come to this,” she said. “And also, I’ve learned that if you see something that you question, you should go for it and don’t stop.” THE NEW YORK TIMES