Is CO2 an Indoor Pollutant? Direct Effects of Low-to-Moderate CO2 Concentrations on Human Decision-Making Performance

TitleIs CO2 an Indoor Pollutant? Direct Effects of Low-to-Moderate CO2 Concentrations on Human Decision-Making Performance
Publication TypeJournal Article
Refereed DesignationRefereed
LBNL Report NumberLBNL-6196E
Year of Publication2012
AuthorsSatish, Usha, Mark J. Mendell, Krishnamurthy Shekhar, Toshifumi Hotchi, Douglas P. Sullivan, Siegfried Streufert, and William J. Fisk
JournalEnvironmental Health Perspectives
Volume120
Start Page1671
Issue12
Pagination1671-1677
Date Published12/2012
Keywordscarbon dioxide, cognition, Decision Making, human performance, indoor environmental quality, ventilation
Abstract

BACKGROUND:

Associations of higher indoor carbon dioxide (CO2) concentrations with impaired work performance, increased health symptoms, and poorer perceived air quality have been attributed to correlation of indoor CO2 with concentrations of other indoor air pollutants that are also influenced by rates of outdoor-air ventilation.

OBJECTIVES:

We assessed direct effects of increased CO2, within the range of indoor concentrations, on decision making.

METHODS:

Twenty-two participants 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-hr sessions, all on 1 day, with exposure order balanced across groups. At 600 ppm, CO2 came from outdoor air and participants' respiration. Higher concentrations were achieved by injecting ultrapure CO2. 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 CO2 level. Data were analyzed with analysis of variance models.

RESULTS:

Relative to 600 ppm, at 1,000 ppm CO2, 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.

CONCLUSIONS:

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. Confirmation of these findings is needed.

DOI10.1289/ehp.1104789
Short TitleEnviron Health Perspect.
Refereed DesignationRefereed