## Key Ideas > [!abstract] Core Concepts > > - **Cognitive performance impact**: Elevated CO₂ levels reduce decision-making and cognitive function in classrooms > - **Research evidence**: Satish et al. (2012) showed performance reductions at moderate CO₂ levels > - **Practical solutions**: Proper ventilation and air quality monitoring essential for optimal learning environments ## Definition **Carbon Dioxide Impact**: Elevated CO₂ levels in classrooms can impair cognitive performance by reducing oxygen availability to the brain, affecting students' ability to think and learn effectively. ## Connected To [[Cognitive Load Theory]] | [[Attention]] | [[Temperature]] | [[Sleep]] --- ## Research evidence Moderately elevated CO₂ levels reduce decision-making performance according to controlled studies (Satish et al., 2012). These effects occur not at extreme levels, but at concentrations commonly found in poorly ventilated classrooms. At 1,000 ppm, cognitive performance shows measurable reduction (Allen et al., 2016). At 2,500 ppm, negative effects become more pronounced (Satish et al., 2012). ## Physiological mechanism Elevated CO₂ levels can lead to hypoxia, where insufficient oxygen reaches the brain and impairs neural function. This reduced cognitive performance affects decision-making abilities, concentration and focus, learning capacity, and memory formation. Proper ventilation reduces CO₂ concentration, which enhances students' cognitive function and learning outcomes (Wargocki & Wyon, 2017; Haverinen-Shaughnessy et al., 2011, 2015; Bakó-Biró et al., 2012). Schools should regularly monitor indoor air quality, including CO₂ levels, to ensure they remain within acceptable limits. ## References Satish, U., Mendell, M. J., Shekhar, K., Hotchi, T., Sullivan, D., Streufert, S., & Fisk, W. J. (2012). Is CO₂ an indoor pollutant? Direct effects of low-to-moderate CO₂ concentrations on human decision-making performance. *Environmental Health Perspectives*, 120(12), 1671-1677. https://doi.org/10.1289/ehp.1104789 Allen, J. G., MacNaughton, P., Satish, U., Santanam, S., Vallarino, J., & Spengler, J. D. (2016). Associations of cognitive function scores with carbon dioxide, ventilation, and volatile organic compound exposures in office workers: A controlled exposure study of green and conventional office environments. *Environmental Health Perspectives*, 124(6), 805-812. https://doi.org/10.1289/ehp.1510037 Wargocki, P., & Wyon, D. P. (2017). Ten questions concerning thermal and indoor air quality effects on the performance of office work and schoolwork. *Building and Environment*, 112, 359-366. https://doi.org/10.1016/j.buildenv.2016.11.020 Haverinen-Shaughnessy, U., Moschandreas, D. J., & Shaughnessy, R. J. (2011). Association between substandard classroom ventilation rates and students' academic achievement. *Indoor Air*, 21(2), 121-131. https://doi.org/10.1111/j.1600-0668.2010.00686.x Haverinen-Shaughnessy, U., & Shaughnessy, R. J. (2015). Effects of classroom ventilation rate and temperature on students' test scores. *PLoS ONE*, 10(8), e0136165. https://doi.org/10.1371/journal.pone.0136165 Bakó-Biró, Z., Clements-Croome, D. J., Kochhar, N., Awbi, H. B., & Williams, M. J. (2012). Ventilation rates in schools and pupils' performance. *Building and Environment*, 48, 215-223. https://doi.org/10.1016/j.buildenv.2011.08.018 ---