@article{25959,
  keywords = {Indoor environmental quality (IEQ), Ventilation, Carbon dioxide, Decision Making, Cognition, Human performance},
  author = {Usha Satish and Mark J Mendell and Krishnamurthy Shekhar and Toshifumi Hotchi and Douglas P Sullivan and Siegfried Streufert and William J Fisk},
  title = {Is CO<sub>2</sub> an Indoor Pollutant? Direct Effects of Low-to-Moderate CO<sub>2</sub> Concentrations on Human Decision-Making Performance},
  abstract = {<h2>BACKGROUND:</h2><p>Associations of higher indoor carbon dioxide (CO<sub>2</sub>) concentrations with impaired work performance, increased health symptoms, and poorer perceived air quality have been attributed to correlation of indoor CO<sub>2</sub> with concentrations of other indoor air pollutants that are also influenced by rates of outdoor-air ventilation.</p><h2>OBJECTIVES:</h2><p>We assessed direct effects of increased CO<sub>2</sub>, within the range of indoor concentrations, on decision making.</p><h2>METHODS:</h2><p>Twenty-two participants were exposed to CO<sub>2</sub> 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-hr sessions, all on 1 day, with exposure order balanced across groups. At 600 ppm, CO<sub>2</sub> came from outdoor air and participants' respiration. Higher concentrations were achieved by injecting ultrapure CO<sub>2</sub>. Ventilation rate and temperature were constant. Under each condition, participants completed a computer-based test of decision-making performance as well as questionnaires on health symptoms and perceived air quality. Participants and the person administering the decision-making test were blinded to CO<sub>2</sub> level. Data were analyzed with analysis of variance models.</p><h2>RESULTS:</h2><p>Relative to 600 ppm, at 1,000 ppm CO<sub>2</sub>, 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 (raw score ratios, 0.06-0.56), but performance on the focused activity scale increased.</p><h2>CONCLUSIONS:</h2><p>Direct adverse effects of CO<sub>2</sub> on human performance may be economically important and may limit energy-saving reductions in outdoor air ventilation per person in buildings. Confirmation of these findings is needed.</p>},
  year = {2012},
  journal = {Environmental Health Perspectives},
  volume = {120},
  pages = {1671-1677},
  month = {12/2012},
  doi = {10.1289/ehp.1104789},
}