PFAS in ski wax: eternal chemicals on the cross-country ski trail
If the perpetual chemicals PFAS enter the environment, they remain there for generations and harm people and nature. Despite increasing bans, many PFAS are still in circulation - including on Swiss slopes and cross-country ski trails, where the toxic substances are released into nature through abrasion from ski wax. Empa researchers were able to detect increased PFAS concentrations in snow samples from the Engadin in connection with a school-leaving examination project - and are urging cross-country skiers to exercise caution.
PFAS - short for «per- and polyfluorinated alkyl compounds» - are currently the subject of numerous discussions and legislative proposals. Many of these so-called «perpetual chemicals» (see box) are harmful to health and the environment. As they can potentially remain in the environment for centuries and accumulate in humans and animals, it is now important to restrict their use as much as possible. This is a challenge, as PFAS are widely used in numerous everyday objects and industrial processes.
Although industry is the largest PFAS emitter, consumers also have a duty. This is because their use is not really necessary everywhere PFAS are used. One example that is particularly relevant for Switzerland is their use in certain ski waxes. The International Ski Federation FIS has already taken action: Since the 2023/2024 season, ski waxes containing fluorine have been banned from all FIS races; their use leads to disqualification. This also applies to Swiss events, such as the Engadin Skimarathon. Ski wax manufacturers have also reacted and switched to fluorine-free products.
However, Swiss slopes and cross-country ski trails are not yet completely PFAS-free. Researchers from Empa's Analytical Center discovered this during a random sample at the Engadin Ski Marathon in March 2025. A few hours after the start of the runners, they took snow samples from the various tracks directly after the start line, as well as further samples around two kilometers after the start and a zero sample far from the trail.
Short distances into the lake
«We measured relatively high values for the typical PFAS from ski wax,» says Markus Zennegg, Head of the Analytical Center. «These are in particular the perfluorinated carboxylic acids with an even chain length of 6 to 14 carbon atoms.» The concentrations were highest at the starting line, where the runners started with freshly waxed skis. After two kilometers, significantly fewer PFAS remained in the snow, as the skis quickly lose their fluorine-containing wax coating through abrasion. Nevertheless, the concentrations were measurably higher there too. «Directly above Lake Sils, this is a cause for concern,» says Empa researcher Stefan Reimann from the «Air Pollutants / Environmental Technology» laboratory, who collected the snow samples. This is because as the snow melts in spring, the eternal chemicals enter the water directly and can accumulate in aquatic organisms and fish.
The fluorine-containing substances in ski wax are intended to improve the gliding properties of the skis and help ambitious cross-country skiers reach their destination faster. However, the differences to modern fluorine-free waxes are now minimal. «The skis of the ten fastest professional skiers at the Engadin Ski Marathon were all tested and no PFAS were found,» says Reimann. «So apparently you can be fast without fluorine.»
Responsibility required
The researchers suspect that a large proportion of the PFAS in the snow is not due to bad intentions on the part of the skiers, but to the fact that amateur cross-country skiers are not yet sufficiently sensitized. This is also supported by the fact that the increased PFAS concentrations were not only measured in the tracks reserved exclusively for the marathon, but also in the area where the normal cross-country ski trail runs. «A block of wax can last for several years,» says Zennegg. «And practically all older ski waxes contain PFAS.» He recommends replacing old ski wax with fluorine-free versions, which are available in stores and labeled accordingly. «It simply makes no sense to allow such stable substances to enter the environment for a few minutes,» adds Reimann.
The researchers have now also taken soil samples from the same locations. They also show significant contamination with the perpetuating chemicals. «At such concentrations, there is already a risk that the PFAS will accumulate in the meat of the cattle grazing there and lead to the permitted limits being exceeded,» warns Zennegg. Further PFAS studies are also in progress: the researchers at the Analytical Center have built up analytical capacities over the past few months to be able to determine around 30 of the most common PFAS in various material and environmental samples, for example from recycling processes.
PFAS, the eternal chemicals
The PFAS class of substances comprises thousands of chemical compounds. They have two things in common: they contain fluorocarbon bonds and they are extremely stable, so they hardly decompose in the environment. The health effects of PFAS are not yet fully understood, but they have been linked to a wide range of conditions, from organ damage to cancer. In the new «Pocket Facts» brochure Empa, Eawag and the Ecotox Center will provide information on perpetual chemicals and how they can be avoided.
