Dr. Walter Hugentobler

Can you say a few words about yourself?

The first five years of childhood I spent in Geneva, were is was born. Due to linguistic barriers for my German speaking mother, we lived almost entirely indoors in a city apartment and on a tiny balcony. The possible consequences of my rare early childhood exposure to natural and rural environments emerged more than 60 years later, as I will explain later on. Even though contacts with the French culture were sparse they spurred a lasting sympathy for the Romandie and Gallic culture. I was five, as we moved to Kloten, then an “airport rural village”, were I lived until I completed my medical study at University of Zurich and my multidisciplinary training as primary care physician.

Did you choose your profession or did it choose you?

My choice to study medicine was based on coincidence but never regretted. For 25 years I struggled with passion and enthusiasm to fulfill the objective of a holistic medical care for all my patients. I joined a small group of primary care physicians with interest in research topics and engaged myself in student teaching. – Around the turn of the millennium I became increasingly aware that the raising numbers of multiresistant and zoonotic infections and immune diseases were (in part) related to our outdated view on hygiene. The built environment, were most of us spend about 90 percent of there lifetime, is misaligned towards costs, building and asset protection and not aimed to protect human health. The HOBEL team of EPFL would call that “not human orientated”. This insight together with the daily experience of dryness related airway problems of my patients working in the super-dry workplace “airplane”, motivated me to study indoor climate impacts on human health.

How and why have you joined the LAPI?

The LAPI team, as part of a joint SNF SINERGIA project, offered me an affiliation with EPFL. – The industrial revolutions relocated humanity from a natural environment into the built environment. Humidity, temperature, convection, microbes, pollution and human activities are the main drivers of outdoor climate and ecosystems – the research field of LAPI. The same factors are driving indoor climates and have major health impacts. Contrary to the outdoor situation, the built environment is easier controllable, mainly anthropogenic and homemade. Therefore architects, builders and facility management bear full responsibility for their consequences. While impacts of indoor climate, convection and pathogens are intensively researched, the “overlooked elephant in the room” is humidity, see HOBEL posts “Air Humidity and Indoor Air Quality”, posted 28th of August 2020, https://www.epfl.ch/labs/hobel/air-humidity-and-indoor-air-quality/ . It is my hope to encourage researchers of LAPI and HOBEL to start interdisciplinary research projects with experts in immunology and other health sciences on impacts of humidity, temperature, convection and microbes on the human boundary layers to the built environment, namely airways and wound surfaces.

What have been some of your biggest challenges?

Not to lose enthusiasm and optimism in a longstanding confrontation with architects, constructors, installers and many of my medical colleagues on subjects like airborne transmission, meaningful disinfection and hygiene, the danger of unmanageable inflow air ducts, misguided ventilation priorities and material selections. First and foremost it is disappointing that indoor experts are still reluctant to realize the consequences of the immanent and permanent competition for the resource “water” in the built environment between thirsty air on one hand and humans, microbes and all hygroscopic materials on the other hand. – A few years ago, as I experienced a transient immune disease called polymyalgia rheumatica, I realized that the lack of exposure to the natural exposome in early childhood might have been a powerful risk factor.

What have been some of your biggest successes?

Since seasonality of respiratory infections gained my attention at the beginning of this century, I was convinced that the main transmission way was aerosols and that low indoor humidity was the main driver for winter seasonality. Since my medical colleagues were not interested in understanding the essence of infectious aerosols, I could convince Prof. Urs Baltensperger from Paul Scherrer Institute to start a multidisciplinary SINERGIA research project on that subject. In Nov. 2019 our IVEA Project “Infectivity of Influenza Viruses in Expiratory Aerosols under Ambient Temperature and Humidities” was approved by the SNF. LAPI and LCE research groups are part of this SINERGIA project and I am honored and proud to follow this project as a partner.

Where is the most interesting place you’ve been?

My medical examination room, where I spent 25 years of my work live – this was my lab and source of most inspirations.

A free thought for the end?

I am confident that the overlooked “elephant in the room”, air humidity, will soon become recognized, since I trust in the sentence of Victor Hugo: Nothing is more powerful than an idea whose time has come!