During the pandemic, I became increasingly aware of the importance of clean air and how CO2 levels can serve as a reliable proxy for indoor air quality. As a rule of thumb, values below 1000 ppm are generally fine. When levels rise to around 2000 ppm, it means that approximately 4% of the air we breathe has already been exhaled by others. Elevated CO2 levels are linked to reduced concentration, increased fatigue, and a general sense of discomfort. At levels significantly above 2000 ppm, symptoms like yawning, headaches, and sleep disturbances can occur.
Out of curiousity I carried a small CO2 monitor (Aranet4) with me, especially for the shared sleeping room. On our trip to the Almtal the first day, air quality was mostly acceptable, with only short spikes above the comfort threshold. The sleeping room at the Welser Hütte was also quite decent – we had kept a window open overnight, which helped maintain fresh air. You can actually see the occasional sharp drops in CO2 levels in the data; these corresponded to moments when someone went to the toilet and left the door open, improving ventilation.
However, in the Pühringer Hütte, some not so intelligent guy closed the window in the dormitory (Matratzenlager) before going to bed. I noticed it but was too tired to get up and reopen it. What followed was the highest CO2 reading I’ve ever recorded: a staggering 8283 ppm. At that level, roughly 15% of the air I was breathing had already been exhaled by others. After about three hours of deep sleep, I woke up with a headache and a noticeable sense of stale, sticky air. A few people were snoring heavily. I finally forced myself to get up and crack the window open again. Immediately, I felt a cool and refreshing breeze. The CO2 values began to drop sharply, and interestingly, the snoring diminished as well. I managed to fall back asleep and slept well until 6:45 a.m.
The return journey to Vienna, unfortunately, was marked by poorer air quality – both trains were crowded, and the CO2 levels reflected that.
Conclusion
It is wise to open a window in a dormitory, both Matratzenlager and Zimmerlager. If you’re cold, you can use the provided blankets or dress yourself with your alternate trekking pants. I prefer a cooler room with fresh air instead of a stuffy room with poor air quality and heavily snoring room mates. I never made this connection before. Could be an interesting field study to explore the link between snoring frequency and poor air quality.
Unfortunately I didn’t bring my Aranet4 device with me into the restaurant rooms. Would have been interesting to see the CO2 graph with full house of customers.
It’s now a week later and I didn’t become sick despite these enormous CO2 values.
