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Be Careful, Crowded Rooms Can Make You Dumber!

An image of attendees at the World Economic Forum.

An image of attendees at the World Economic Forum. They might think a little more slowly thanks to all the carbon dioxide in the crowded room. Image via Wikimedia Commons/Gardiner Pearson

When you feel sleepy in a crowded room, you might think that is because the presenter talks boring stuffs, while actually it may relate with the air composition.

In a traditional point of view, the concentration of carbon dioxide (CO2) in ambient atmosphere is not sufficient to lower our cognitive level, however, a research published on Environmental Health Perspectives has found that the CO2 exhaled from people around you might slow your thinking.

The researchers from SUNY Upstate Medical University and Lawrence Berkeley National Laboratory conducted an experiment by sealing 24 healthy young subjects in a room and tested their decision making ability at different atmospheres of various CO2 concentrations. Almost every one of us has similar experience in a crowded room. The results shows a significant decrease in the subjects’ performances.

Researcher William Fisk from LBNL said, “We always think that the CO2 concentration in buildings is not important and CO2 does not have direct influence on people, and hence, the obvious results do surprise everyone.”

As a part of the study, the researchers performed an experiment with four subjects in an office-like room for three phases with each phase lasting for 2.5 hours and 1 hour rest between each phase. In each phase of the experiment, the room was filled with enough pure CO2 so that the CO2 concentration in the room reached to three different values, namely 600 ppm (ppm, parts per million), 1000 ppm and 25 ppm. As a reference, the CO2 concentration outdoors is approximately 380 ppm, while since we exhale CO2, the indoor CO2 concentration is generally much higher. When we are talking about a crowded classroom or conference room, the concentration can further increase to 1000 ppm or even over 3000 ppm.

During the test, the subjects in the sealed room had to complete the decision making tasks—decision making simulation test designed by New York State University, which requires the subjects to make decisions according to assumed situations. Then the subjects were scored in nine different aspects including basic activity, applied activity, focused activity, task orientation, initiative, information orientation, information utilization, breadth of approach and basic strategy.

 Impact of CO2 on Human Decision Making Performance.

Impact of CO2 on Human Decision Making Performance. The experiment evaluated the influence of CO2 concentration on subjects’ decision making performance in 9 aspects, namely basic activity, applied activity, focused activity, task orientation, initiative, information orientation, information utilization, breadth of approach and basic strategy.(Image source:Environmental Health Perspectives,via blogs.smithsonianmag.com)

Prior to the experiments, the research expected the subjects’ performances to be lower as the experiment proceeded, however, they are surprised that the influence of CO2 is so significant.  When the CO2 concentration is 1000 ppm, the nine aspects of decision making abilities are decreased in a range of 11% to 23%. When the CO2 concentration is 2500 ppm, a significant decrease in decision making performance is observed, with the nine aspects decreased by 44% to 94%. The most impacted aspect is the subjects’ decision-making thinking and action-taking ability. “The influence of 2500 ppm CO2 concentration is amazing and unbelievable, “said the scientist Mark Mendell from LBNL.

In the past, scientists believed that CO2 had to reach a high concentration before it can directly affect human health. “The previous researches observed the conditions at 10,000 and 20,000 ppm and scientists thought that only at such high concentrations can CO2 take effect,” Mendell said, “that is why these new findings are surprising.”

In most cases, indoor environment specialists evaluate improper ventilation and existence of other pollutant via CO2 level, however, CO2 itself is not an important pollutant. “We have seen that high level of CO2 is related with the increased absence rate of students, as well as poor performance in their academic tasks, but we didn’t find CO2 is the principal culprit.” Said Fisk when interviewing with Science News.

Recently, in order to construct more energy-saving buildings, we lower the ventilation level in many classrooms. “To improve energy using efficiency, many buildings are constructed in a closed fashion to lower the management cost,” said Mendell, “this may have negative effects on residents and should not be ignored.”

According to the standard of U.S. Environmental Protection Agency (EPA), the CO2 concentration in classrooms can’t be 700 ppm higher than that of outdoors, which means the value is generally ranging from 1,000 to 1,100 ppm. The standard were originally developed to ensure proper ventilation and decreasing indoor body odor, but not aimed at the negative effects of CO2 on human body.

This study has a small sample and the author points out that in order to be more convincing, experiments in larger extent should be implemented. If the same result is obtained with a larger sample, then we should really reconsider the way we design buildings and rethink why people feel tired when having redundant presentations.

Reference: Smithsonianmag, The Carbon Dioxide in a Crowded Room Can Make You Dumber

Image source: blogs.smithsonianmag.com