The small city of Davos in southeastern Switzerland, located at an altitude of 1,560m above sea level in the Swiss Alps, attracted tuberculosis patients back in the 1800s and 1900s after scientists discovered that clean mountain air had a positive effect on their health. However, with the development of antibiotics, the sanatoriums eventually lost their purpose. Today that same clean Davos air, marked by the absence of tree pollen, such as birch, oak or alder, minimal air pollution and extremely low amounts of indoor dust mites – presumably because of the cooler and dryer climate – is a draw for asthma and allergy patients seeking treatment in the town’s clinics. Allergic diseases have become more prevalent in recent decades. They now affect more than one billion people worldwide, with estimates suggesting there could be up to four billion sufferers by 2050. While the reasons for this are not yet fully understood, experts believe several factors can contribute significantly to developing chronic diseases. Today we are exposed to many pollutants, such as chemical substances in our diet or cosmetics, worsening air pollution and microplastics. Thanks to the proximity to allergy patients and the ability to analyse various biosamples, Davos has become an ideal location for research and experiments in this field. As they pursue their exploration of the scientific side of the resort, Sara Ibrahim and Michele Andina visit the Swiss Institute of Allergy and Asthma Research (SIAF), where around 50 biologists, biochemists and physicians are working to understand what's causing allergic diseases and find preventive and curative treatments. This podcast is an audio version of the SWI swissinfo.ch video series with the same title.  Find out more about science research in Switzerland on www.swissinfo.ch/science Hosted by: Jo Fahy Journalist: Sara Ibrahim Journalist/Sound: Michele Andina Please sign up for our Free newsletter on Swiss Democracy.   SWI swissinfo.ch is a public service media company based in Bern Switzerland. It publishes independent news and information in 10 languages about Switzerland for a global audience.