“You should get some fresh air, to clear your mind”. These words, or something akin to them, have been uttered countless times everywhere throughout all of time. There very much is something to be said about the rejuvenating quality of fresh air. As it turns out, scientific evidence backs this age-old wisdom—quite a heap of evidence at that, as we will examine here.
You have probably long suspected this, but did you know that too much carbon dioxide (CO2) in a room will make you sleepy and slow? It is becoming more and more accepted within the scientific community that too high CO2 concentrations affect cognitive function.
Is it any wonder then that sitting in a poorly ventilated space, such as an office or a classroom, will rob you of your energy, rendering you lethargic and struggling to keep from drifting off to sleep?
“Prior research has found that with higher indoor levels of CO2, indicating less outdoor air ventilation per person, people tend to be less satisfied with indoor air quality, report more acute health symptoms (e.g., headache, mucosal irritation), work slightly slower, and are more often absent from work or school.”
Imagine a lot of people sitting in a poorly ventilated classroom for instance (as is the norm due to energy-saving measures), breathing in oxygen (O2) and breathing out CO2. They are going to slowly and steadily increase the CO2 levels. Thus, over time it becomes harder and harder to stay focused as sluggishness invariably seeps in as our brains slow down. Such levels of CO2 certainly impact our decision-making and critical-thinking abilities.
The reason for this poor ventilation that we have gotten accustomed to is to save energy. Now, this is paradoxical given that work performance has been shown to decrease when CO2 levels are too high, thus nullifying at least some of the costs saved by choosing energy saving ventilation—or lack thereof.
We spend about 90% of our time indoors. Hence, we would be wise to seriously take into consideration how air circulation in buildings affects our health. It will not do to construct buildings merely with the goal of being tightly sealed and energy efficient while ignoring the proven effects this has on our health.
Aside from the CO2-induced tiredness associated with poor circulation, there is yet another health hazard: that of “increased concentration of indoor pollutants” also known as “sick building syndrome (SBS)” which came about as our offices and homes became ever more airtight having been first reported in the 1980s. While so-called “green buildings” have lower levels of indoor pollutants, they still have poor circulation and are therefore effective at trapping CO2—a problem that plagues most modern buildings.
“On average, a 400-ppm increase in CO2 was associated with a 21% decrease in a typical participant’s cognitive scores across all domains”. We tend to start noticing air quality when CO2 content rises above 600 parts per million (ppm). Compare this to outdoor CO2 levels which are about 400 ppm. Yet, the average building has 1000 ppm.
“[There are]literally dozens of studies in the past two decades that find low to moderate levels of CO2 have a negative impact on productivity, learning, and test scores”. 
Throughout all of our time as humans, since our primeval ancestors right down to our modern history, CO2 levels have oscillated between 180 to 280ppm; also added to this is the fact that our ancestors mostly spent their time outdoors or in well aerated caves. Even in more recent times, dwellings and working spaces have not been as tightly sealed as they are now. These energy saving measures of sealing buildings are a recent phenomenon. In short, we as a species have not been exposed to such constant high amounts of CO2 as we are now.
With all this in mind, the question begs to be asked: Just how much will the ever rising and ever accelerating levels of CO2 affect our well-being and mental faculties? Too much CO2 will no longer be confined to the indoors; it will be ubiquitous as there will be no chance to escape this suffocating air by opening the window or going outside.
Given that a high concentration of CO2 in workspaces and homes correlates with lower cognitive capabilities and well-being, it is most certainly wise to address this problem. Understanding the effects of indoor CO2 levels on human cognition is fundamental and will better prepare us as global CO2 levels rise. We should not take our fresh air for granted. It rejuvenates, it clears our head and it makes us feel better, as has been known throughout all of time.
Written by: Dannie Kamete