The little-known factor that can crush cognitive function, and what to do about it

Most people will not feel great or perform optimally in a room that feels ‘stuffy’ or ‘airless’. In this situation, someone may well feel compelled to open a window or door ‘to let some air in’. Actually, the relief that comes from increased ventilation is less about what it brings in than about what it lets out. This is because it’s not so much a lack of oxygen as a buildup of carbon dioxide that causes the feeling of stuffiness.

Outdoor air generally has a CO2 level of around 250-350 parts per million (ppm), while a well-ventilated indoor space will have levels of about 350-1,000 ppm. However, a lack of ventilation can lead to significantly higher CO2 levels, which can impair brain function and performance.

This was tested in a study in which office workers were, unbeknownst to them, exposed to three CO2 concentrations on different days: 550, 945, and 1,400 ppm.1 Compared to the lowest CO2 concentration, exposure to CO2 at 945 ppm reduced overall cognitive function by 15%. At a CO2 concentration of 1,400, cognitive function was halved. Overall, for every 400 ppm increase in CO2 in the air, cognitive function fell by 21% on average.

CO2 MONITORING

CO2 levels can be monitored using appropriate tech, such as Netatmo’s ‘Smart Indoor Air Quality Monitor’ that provides real-time data on the level of carbon dioxide (as well as other factors, including temperature and humidity) via a smartphone app. The app will also send alerts when CO2 levels exceed a certain threshold. Note: I use one of these devices, but have no affiliation.

My advice is to keep CO2 levels below about 700 ppm. I’ve found, from experience, that what's generally required here is two points through which air can flow, such as a window and a door that are ajar, preferably on opposite sides of a room.

VOLATILE ORGANIC COMPOUNDS

Some internal spaces can be polluted with chemical entities known as ‘volatile organic compounds’ (VOCs) that are released from some paints, carpets, furniture, soft furnishings and the like. Common culprits include benzene, toluene and xylene. VOCs are believed to play a part in a phenomenon known as ‘sick building syndrome’, where some individuals can feel unwell in certain office or other indoor environments.

As with CO2, VOC-measuring meters are available and relatively inexpensive. But, again, good ventilation is the key to managing potential issues here. Another approach is to install some potted plants (real ones!) in the room where you work. Plants absorb carbon dioxide during the day, but perhaps less well known is that soil microbes also suck up VOCs very efficiently.

WHAT DIFFERENCE DOES IT MAKE?

Is there any evidence that improving the quality of the air in our immediate environment helps us do our jobs better? In the study I referred to above,1 at certain points, subjects were exposed not only to elevated CO2 levels but also to VOCs in the air. Inevitably, cognitive function suffered. Conversely, in an adequately ventilated environment with low CO2 and VOC levels, cognitive function was more than twice as good.

REFERENCES:

1. Allen JG, et al. Associations of Cognitive Function Scores with Carbon Dioxide, Ventilation, and Volatile Organic Compound Exposures in Office Workers: A Controlled Exposure Study of Green and Conventional Office Environments. Environ Health Perspect 2016;124:805–812