Elevated CO2 Levels Directly Affect Human Cognition, New Harvard Study Shows

http://thinkprogress.org/climate/2015/10/26/3714853/carbon-dioxide-impair-brain/

by Joe Romm Oct 26, 2015

In a landmark public health finding, a new study from the Harvard School of Public Health finds that carbon dioxide (CO2) has a direct and negative impact on human cognition and decision-making. These impacts have been observed at CO2 levels that most Americans — and their children — are routinely exposed to today inside classrooms, offices, homes, planes, and cars.

Carbon dioxide levels are inevitably higher indoors than the baseline set by the outdoor air used for ventilation, a baseline that is rising at an accelerating rate thanks to human activity, especially the burning of fossil fuels. So this seminal research has equally great importance for climate policy, providing an entirely new public health impetus for keeping global CO2 levels as low as possible.

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They found that, on average, a typical participant’s cognitive scores dropped 21 percent with a 400 ppm increase in CO2.

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The researchers explain, “The largest effects were seen for Crisis Response, Information Usage, and Strategy, all of which are indicators of higher level cognitive function and decision-making.”

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NASA has also observed CO2-related health impacts on International Space Station (ISS) astronauts at much lower CO2 levels than expected and has identified a mechanism by which CO2 levels could affect the brain, as I will discuss in Part 2. As a result, NASA has already lowered the maximum allowable CO2 levels on the space station. The ISS crew surgeon who is the lead for studying the impact on astronauts of CO2 (and other gases) told Climate Progress he considers the original LBNL-SUNY study “very credible.”

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All of this new research is consistent with — and actually helps explain — 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.

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For most of human evolution and modern history, CO2 levels in the air were in a fairly narrow and low range of 180 to 280 parts per million. Also, during the vast majority of that time, humans spent most of their time outdoors or in enclosures that were open (like a cave). Even once humans built dwellings, those were not tightly sealed as modern buildings are. So even though we generate and breathe out CO2, homo sapiens were not generally exposed to high, sustained CO2 levels.

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But in recent decades, outdoor CO2 levels have risen sharply, to a global average of 400 ppm. Moreover, measured outdoor CO2 levels in major cities from Phoenix to Rome can be many tens of ppm higher — up to 100 ppm or more — than the global average. That’s because CO2 “domes” form over many cities primarily due to CO2 emissions from traffic and local weather conditions.

The outdoor CO2 level is the baseline for indoor levels. In buildings — the places where most people work and live — CO2 concentrations are considerably higher than outdoors. CO2 levels indoors that are 200 ppm to 400 ppm higher than outdoors are commonplace — not surprising since the design standard for CO2 levels in most buildings is 1000 ppm. In addition, that differential increases when more people are crammed into a space and when the ventilation is not adequate. As the Harvard researchers point out, in recent decades, buildings have become more tightly sealed, and there has been less exchange of inside air with fresh outside air.

How high can CO2 levels get indoors? As but one salient example, the 2012 LBNL-SUNY article notes, “In surveys of elementary school classrooms in California and Texas, average CO2 concentrations were above 1,000 ppm, a substantial proportion exceeded 2,000 ppm, and in 21% of Texas classrooms peak CO2 concentration exceeded 3,000 ppm.”

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Success at Paris, as I have written, would buy us 5 to 10 years in the fight to avoid catastrophe. But we would still be on a path to 675 ppm, which is too high for both the climate change impacts and the direct human cognition impacts. Worse, that level of warming will likely trigger many major carbon-cycle amplifying feedbacks that are not included in the climate models, such as permafrost melting. So we must take stronger action.

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