Indoor Climbing May Pose Unexpected Health Risks, Study Finds

A popular modern sport may come with hidden health concerns, according to new research, the Daily Mail reports.

Scientists have found that indoor rock climbing, also known as bouldering, could expose participants to potentially harmful airborne chemicals released from climbing shoe soles.

Researchers from the University of Vienna discovered that rubber compounds used in climbing footwear emit pollutants into the air inside climbing gyms. These substances—similar to those found in car tires—are used to enhance grip and durability but can include toxic chemicals linked to respiratory issues, inflammation, and even cancer.

The study, published in Environmental Science and Technology Air, involved air quality measurements from nine climbing gyms across Austria, France, Spain, and Switzerland. Using a device known as an impinger, which simulates human lungs, the team found pollutant levels in some gyms rivaled those found on heavily trafficked urban roads in major cities like those in China.

“These substances do not belong in the air we breathe,” said Professor Thilo Hofmann, one of the study’s authors. “The levels we measured are among the highest ever documented worldwide, comparable to multi-lane roads in mega-cities.”

Climbing shoes contain chemicals such as 6PPD-quinone—a compound previously linked to lung scarring and organ damage in animal studies—and benzothiazole, a chemical associated with increased bladder cancer risk in certain industrial settings.

While the long-term health effects of frequent exposure to these chemicals remain unclear, the research team advocates for immediate action. Recommendations include improving gym ventilation and encouraging manufacturers to use safer materials in shoe design.

Environmental scientist Anya Sherman, a co-author of the study, pointed out that many climbers are already familiar with the issue, referencing the visible black residue left on footholds in climbing gyms.

“Climbers wipe it off to get a better grip, and it gets kicked up into the air,” she explained.

Until further safety measures are adopted, Sherman advises climbers to consider visiting gyms during off-peak hours to minimize exposure to airborne particles.

Indoor climbing has surged in popularity in recent years, fueled in part by social media and celebrity interest. A 2018 survey found that 1 in 100 people in the UK and 1 in 20 in the US engaged in indoor climbing, with around 20% of users visiting gyms regularly each week.