Atmospheric CO2 can cause cognitive impairmentDate: 23 April 2020 Tags: Miscellaneous
Rising atmospheric carbon dioxide (CO2) concentrations will cause urban and indoor levels of the gas to increase, and that may significantly reduce our basic decision-making ability and complex strategic thinking, according to a new study.
High level cognitive domains like decision-making and planning are especially susceptible to increasing CO2 concentrations.
By the end of the century, people could be exposed to indoor CO2 levels up to 1400 parts per million--more than three times today's outdoor levels, and well beyond what humans have ever experienced.
Building ventilation typically modulates CO2 levels in buildings, but there are situations when there are too many people and not enough fresh air to dilute the CO2. They also build up in poorly ventilated spaces over longer periods of time, such as overnight while sleeping in bedrooms.
Put simply, when we breathe air with high CO2 levels, the CO2 levels in our blood rise, reducing the amount of oxygen that reaches our brains. Studies show that this can increase sleepiness and anxiety, and impair cognitive function.
And outdoor CO2 in urban areas is higher than in pristine locations. The CO2 concentrations in buildings are a result of both the gas that is otherwise in equilibrium with the outdoors, but also the CO2 generated by building occupants as they exhale.
Researchers developed a comprehensive approach that considers predicted future outdoor CO2 concentrations and the impact of localized urban emissions, a model of the relationship between indoor and outdoor CO2 levels and the impact on human cognition.
They found that if the outdoor CO2 concentrations do rise to 930 ppm, that would nudge the indoor concentrations to a harmful level of 1400 ppm. At this level, some studies have demonstrated compelling evidence for significant cognitive impairment.
The cognitive impacts of rising CO2 levels represent what scientists call a "direct" effect of the gas' concentration, much like ocean acidification. In both cases, elevated CO2 itself--not the subsequent warming it also causes--is what triggers harm.