Indoor Carbon Dioxide Linked to Reduced Brain Function

Previous studies have suggested that higher indoor carbon dioxide (CO2) concentrations associated with a variety of health symptoms.  Mark Mendell, from the Lawrence Berkeley National Laboratory (California, USA), and colleagues enrolled 22 adults in a study in which subjects were exposed to CO2 at 600, 1,000, and 2,500 ppm in an office-like chamber, in six groups. Each group was exposed to these conditions in three 2.5-hour sessions, all on one day, with exposure order balanced across groups. Under each condition, participants completed questionnaires on health symptoms and perceived air quality, and a computer-based test of decision-making performance.  Relative to 600 ppm, at 1,000 ppm CO2, the researchers observed moderate and statistically significant decrements occurred in six of nine scales of decision-making performance. At 2,500 ppm, large and statistically significant reductions occurred in seven scales of decision-making performance.  The study authors conclude that: “Direct adverse effects of CO2 on human performance may be economically important and may limit energy-saving reductions in outdoor air ventilation per person in buildings.”