Climbing Shoes and Air Quality: New Findings Reveal Overlooked Hazards in Indoor Gyms
A new investigation featured in Environmental Science and Technology Air has created waves within the climbing community, exposing an unforeseen environmental and health challenge within indoor climbing venues. Scholars from the University of Vienna and EPFL Lausanne have detected potentially dangerous airborne chemicals emitted from the specialized rubber soles of climbing shoes—at concentrations similar to pollution levels found on busy city highways.
Identifying the Source of Contamination
Climbing shoes are distinctive for their high-performance soles designed for optimal grip on artificial walls. However, akin to car tires, these rubber soles are subject to wear and tear. According to Anya Sherman, the study’s lead author and an environmental scientist at the Centre for Microbiology and Environmental Systems Science at the University of Vienna, “The soles of climbing shoes are engineered products, much like car tires.”
Such wear produces tiny rubber particles containing a variety of chemical ingredients. These particles gather on climbing holds, mats, and floors of the facilities. When climbers tumble, dust off holds, or walk around, these particles are released into the air, presenting an inhalation risk for both gym-goers and staff.
Chemical Substances Found in the Air
The research group examined 30 different models of climbing shoes and environmental samples from nine climbing gyms across Austria, Switzerland, France, and Spain. The outcome was alarming: they identified 15 rubber-derived compounds (RDCs) consistently present in the samples.
One especially troubling compound is 6PPD, a common rubber stabilizer utilized in both automotive tires and the rubber used in climbing shoes. When 6PPD interacts with ozone, it converts into 6PPD-quinone—a substance associated with harmful effects in aquatic ecosystems, including the death of salmon.
Airborne Levels Comparable to Urban Roadways
Researchers were particularly astonished by the airborne concentration of these RDCs. “The levels we documented are among the highest ever recorded globally, comparable to major thoroughfares in large cities,” stated Thilo Hofmann, Professor of Environmental Geosciences at the University of Vienna and the study’s corresponding author.
The team discovered that frequent climbers and gym employees might face significantly higher exposure levels compared to individuals residing near polluted streets or working in specific industrial jobs. In the most impacted facilities, daily intake estimates soared to as much as 29 nanograms of these compounds per kilogram of body weight each day.
Uncertainties Regarding Long-Term Health Effects
While the short-term health risks remain largely unclear, the researchers warn that chronic exposure to RDCs could result in serious health consequences over time—particularly for susceptible populations like children. Hofmann cautioned, “These substances should not be present in the air we breathe. It is prudent to take action before fully understanding the risks involved.”
This study illuminates a previously unnoticed route for human exposure to environmental pollutants—through participation in indoor sports. With the growing popularity of indoor climbing worldwide, the implications are extensive. For example, in the United States, over 4% of the population utilized indoor climbing gyms in 2018, with many visiting multiple times each week.
Strategies for Improvement: Cleaner Gyms and Safer Footwear
Fortunately, many climbing facility operators showed willingness to enhance air quality. Researchers proposed various strategies to diminish airborne chemical levels:
– Improved ventilation and air purification systems
– Regular and intensified cleaning procedures focused on rubber dust removal
– Advocacy for manufacturers to create more environmentally friendly rubber materials for climbing shoes
“There is an urgent necessity to transition to sole materials with fewer harmful compounds,” emphasized Hofmann. He noted that shoe manufacturers are often unaware of the “mix of undesirable chemicals” within the rubber they employ.
Looking Forward with Hope
Despite the alarming discoveries, the climbing community need not forsake the sport. Study author Anya Sherman remains optimistic: “I will continue climbing, and I believe our research will encourage better conditions in climbing gyms.”
The study acts as both a wake-up call and a rallying cry for climbers, facility operators, equipment manufacturers, and healthcare professionals alike. By increasing awareness of this concealed form of pollution, scientists aspire to encourage the development of healthier practices and materials—ensuring the air in indoor gyms remains as pristine as the exhilaration of climbing.
For the time being, experts advise climbers to advocate for better air quality in their gyms and stay updated as further research unfolds.
Read the full study here: Environmental Science and Technology Air – DOI: 10.1021/acsestair.5c00017
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