During the COVID-19 pandemic, the WHO and various governments recommended to wear face masks in public and at work. Though helpful in preventing the spread of COVID-19, mask use can have negative consequences. For instance, nursing personnel wearing a mask during a 12 h shift had an increase in arterial carbon dioxide tension (PaCO2). Others have reported that mask use not only induces hypercapnia but also hypoxemia, particularly during physical exercise. The latter is of particular importance for people living or working at altitude. At altitude, oxygen saturation (SaO2) while mask wearing might be affected to a larger extend since small changes in arterial oxygen tension (PaO2) may lead to large changes in SaO2 (steep part of the oxygen dissociation curve). Hypoxia may affect cognitive performance possibly affecting work performance and leading to work and recreational accidents. Moreover, hypoxia and hypercapnia both increase sympathetic nervous activity which is involved in the pathophysiology of many cardiovascular and metabolic diseases.

We aim at assessing how different types of masks affect SaO2, PaCO2, cerebral blood flow and oxygenation, oxidative stress as well as cognitive function and perception of comfort at rest and during exercise performed at different altitude levels. Furthermore, we aim at developing masks that have an increased breathability but preserved microbial filtering properties.

As a side arm of this project, we seek to develop an eco-friendly mask. Masks currently available on the marked are mainly composed of polyester or polypropylene, which are among the most dangerous and polluting materials, especially if not properly disposed of. Recent studies have shown that they accumulate in rivers, lakes and oceans, representing over 90% of the pollution from microplastics in some areas of the planet. Given the imminent problem it is crucial to find alternative materials for the production of masks with a reduced environmental impact.

In phase 1, we will assess the effects of surgical masks and FFP-2 masks on SaO2, PaCO2, cerebral blood flow and oxygenation, oxidative stress as well as cognitive function and perception of comfort. In a randomized cross-over study we will include 16 participants (8 males and 8 females; sample size calculated). Each participant will perform the experiment twice, once at sea level and once at an altitude of 3000 m in a hypobaric chamber (terraXcube, Bolzano). Each experiment consists of a baseline measurement period (30 min), after which participants will be randomly assigned to wear either a surgical mask or an FFP-2 mask. Thereafter, participants will undergo two resting phases (15 min) and two exercise phases (cycle ergometer with an intensity of 1 W/kg body weight for 15 min), each with cross-over of the masks, with a wash-out period of 15 min in-between. The following parameters will be measured, either continuously or at the beginning and end of each phase: SaO2, PaO2, PaCO2, heart rate, breathing rate, body temperature, NIRS (to investigate cerebral oxygenation), cognitive tests.

In phase 2, we will develop a mask with higher breathability compared to currently available masks but preserved bacterial filtration efficiency (BFE). Most surgical masks are composed of 3 different layers of non-woven fabric. The outer layer confers mechanical resistance and has hydrophobic properties; the intermediate layer is a meltblown and made up of microfibers with a diameter of 1-3 µm and performs the microbial filtering function; the inner layer protects the skin from the filtering layer. To pursue our goal, we will focus on the intermediate layer and look for a meltblown of high quality in terms of BFE and breathability. In the case we will not be able to find an already existing meltblown with the desired characteristics, we will try to develop a new meltblown with a high degree of breathability and preserved BFE.

In a third phase, we will evaluate how the newly developed mask influences oxygenation and decarboxylation as described above.